Journal Pre-proof Crustacea (Anomura, Brachyura) from the Miocene of Veracruz and Chiapas, Mexico: New records and new species Javier Luque, Torrey Nyborg, Jesús Alvarado-Ortega, Francisco J. Vega PII:
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Journal of South American Earth Sciences
Received Date: 5 January 2020 Revised Date:
5 March 2020
Accepted Date: 6 March 2020
Please cite this article as: Luque, J., Nyborg, T., Alvarado-Ortega, Jesú., Vega, F.J., Crustacea (Anomura, Brachyura) from the Miocene of Veracruz and Chiapas, Mexico: New records and new species, Journal of South American Earth Sciences (2020), doi: https://doi.org/10.1016/ j.jsames.2020.102561. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
Crustacea (Anomura, Brachyura) from the Miocene of Veracruz and Chiapas, Mexico: new records and new species Javier Luque a,b, Torrey Nyborg c, Jesús Alvarado-Ortega d and Francisco J. Vega d,* a
Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109, USA, [email protected]
Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada, [email protected]
Department of Earth and Biological Sciences, Loma Linda University, California, 92350, USA, [email protected]
Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, CdMx, 04510, Mexico, *[email protected]
ABSTRACT We report several new crab specimens, representing new taxa and new occurrences from the Miocene of Veracruz and Chiapas, SE Mexico. Most of the specimens were collected by the late Emily H. Vokes, in 1963 from outcrops of the Agueguexquite Formation, Veracruz, Mexico. The age range of the studied material support an upper Miocene age for the Agueguexquite Formation, as previously suggested. Ranina sp. and Portunus sp. cf. P. atecuicitlus Vega, Feldmann, Villalobos-Hiriart and Gío-Argáes, 1999 from the middle Miocene, Tuxpan Formation, are also reported. We also illustrate an incomplete portunoid specimen from the lower Miocene Tulijá Formation of Chiapas, similar to Necronectes A. Milne Edwards, 1881. The presence of Hepatus Latreille, 1802, Persephona Leach, 1817, and Euphylax Stimpson, 1862a, in the Agueguexquite Formation represent the first record of these genera in the fossil record of Mexico. The occurrence of Eupilumnus? vokesae 1
Luque, sp. nov. would represent the first fossil record of the genus known to date, extending its stratigraphic record into the Miocene. Eurytium granulosus Schweitzer, Velez-Juarbe, Martinez, Collmar-Hull, Feldmann and Santos, 2008, first reported from the Miocene of Puerto Rico is also identified among the specimens here studied. Keywords: Decapoda, Anomura, Brachyura, Miocene, Veracruz, Chiapas, Mexico.
1. INTRODUCTION Several new specimens, representing new occurrences of previously reported species and new taxa from the Miocene of Veracruz and Chiapas, SE Mexico, are here reported and illustrated. Most of the specimens were collected by the late Emily H. Vokes, in 1963 from newly exposed outcrops of the Agueguexquite Formation, when a highway was built near Coatzacoalcos, Veracruz, nearby Nuevo Teapa (locality TU1046, Fig. 1). The Agueguexquite Formation is a shallow transgressive marine unit that crops out in southeastern Mexico in southern Veracruz and northern Chiapas (Castillo-Tejero, 1955). Initially the formation was considered to range from the upper Miocene to the lower Pliocene, the age of this formation has been recently constrained to the middle to late Miocene, based on benthic foraminifera, calcareous nannoplankton, and strontium isotopic dating (Pineda-Salgado et al., 2016). The Agueguexquite Formation is fossiliferous and has yielded several well preserved molluscs (Perrilliat and Flores-Guerrero, 2011; Pineda et al., 2016). Crustaceans are underreported, with only one species of ghost shrimp and one crab previously reported (Vega et al., 2009). So far, only six fossil crab species have been reported from Veracruz, Raninoides mexicanus Rathbun, 1930a (middle Miocene, Tuxpan Formation, additional specimen here illustrated); Calappa zurcheri Bouvier, 1899 (Oligocene), ?Mursia sp., Necronectes tajinensis Vega et al., 1999 and Portunus 2
atecuicitlis Vega et al., 1999 (middle Miocene, Tuxpan Formation, additional specimens here reported), and Eurytium sp. (Pliocene) (Vega et al., 1999; Vega et al., 2009; Luque et al., 2017). An additional specimen classified as Necronectes sp. cf. N. proavitus (Rathbun, 1918) from the Lower Miocene Tulijá Formation of Chiapas (see Martínez et al., 2017) is also here reported collected near the Chacamax River, Chiapas. To our knowledge, the presence of Hepatus Latreille, 1802, Persephona Leach, 1817, and Euphylax Stimpson, 1862a in the Agueguexquite Formation, represent the first record of these genera in Mexico, and confirms their wide distribution in the Americas since at least the mid-late Miocene (Luque et al., 2017). The occurrence of Eupilumnus? vokesae Luque, sp. nov. may represent the first fossil record of the genus known to date, and would extend its stratigraphic record into the Miocene.
2. GEOLOGICAL SETTING Detailed geology of the lower Miocene Tulijá Formation was reported by Martínez et al. (2017) and for the middle Miocene Tuxpan Formation by Vega et al. (1999). The Agueguexquite Formation crops out in southeastern Mexico, in southern Veracruz and northern Chiapas. Its age was recently formally determined, based on relative ages of benthic foraminífera, calcareous nannoplankton,and isotopic stratigraphy (87Sr/86Sr) taken from simples of well-preserved mollusc shells (Pineda-Salgado et al., 2016). These authors, basedon calcareous nannoplankton biostratigraphy, constrained its age as middle-late Miocene, also supported by the Tortonian age (late Miocene, 8.8 My) obtained from isotopic stratigraphy. Most of the fossil crustaceans here reported were collected by Emily H. Vokes in the same outcrops where those dates were recovered. The benthic foraminífera indicated a broad stratigraphic range (Miocene-Pliocene) for the Agueguexquite Formation 3
Pineda-Salgado et al. (2016). Previous studies considered an age between Miocene and Pliocene, based on mollusc biostratigraphy (Pineda-Salgado et al., 2016) collected samples from three localities of the Agueguexquite Formation in Veracruz, previously reported as TU-638, TU-1046 (now covered by dense vegetation) (Fig. 2), and TU-1025, this last one a little older, from the lower Miocene Concepción Inferior Formation, (Pineda-Salgado et al., 2015) (Fig. 3). Locality of the early Miocene incomplete portunoid from Chiapas was found in localities reported by Martínez et al. (2017) and those from the middle Miocene Tuxpan Formation can be seen in Vega et al. (1999).
3. MATERIALS AND METHODS The new fossil specimens from the upper Miocene of the Agueguexquite Formation here studied were collected by Emily H. Vokes in 1963, and formed part of the invertebrate paleontology collections of Tulane University. The material is currently deposited at the Invertebrate Paleobiology collections of the United States National Museum of Natural History, Smithsonian Institution, Washington, D.C., USA, under the acronym USNM. All the USNM fossil specimens were photographed dry and coated with sublimated ammonium chloride. Additional specimens are deposited at the Colección Nacional de Paleontología, Instituto de Geología, Universidad Nacional Autónoma de México, Mexico City 0510, Mexico, under acronym IGM. Fossil specimens were photographed dry and coated with sublimated ammonium chloride.
4. SYSTEMATIC PALEONTOLOGY Order Decapoda Latreille, 1802 Infraorder Anomura MacLeay, 1838 4
Superfamily Paguroidea Latreille, 1802 Family Diogenidae Ortmann, 1892 Genus Petrochirus Stimpson, 1858 Petrochirus sp. Fig. 4 Description. Chelipeds massive, strongly ornamented throughout, with closely spaced coarse primary tubercles, separated by deep grooves; primary tubercles bearing multiple secondary tubercles. Left chelipeds studied are smaller than the right cheliped, with subsquare outline, and propodus about as long as high, with straight margins; dactyli and pollex short, stout, longer than wide, with rounded tips. Material examined. Two specimens, USNM PAL 770829 and USNM PAL 770830. Measurements (in mm). USNM PAL 770829, length of right chela = 62.2; height = 38.1. Remarks. The cheliped remains of Petrochirus from the Agueguexquite Formation in Veracruz here described were found isolated, therefore it is not possible to compare the size proportions between left and right chelipeds from the same individual. Overall, extant Petrochirus species have sub-equal chelipeds, with the right cheliped being slightly larger than the left one (sensu Williams, 1984). Cheliped remains of Petrochirus spp. in the Americas have been found in Eocene to Pleistocene rocks of Venezuela, Panama, Colombia, Mexico, Florida, Bahamas, Dominican Republic and Jamaica (see Luque et al., 2017 for geographic and stratigraphic details of these occurrences). To date, the only fossil records of Petrochirus known from Mexico are restricted to the lower and middle Miocene of Chiapas (Vega et al., 2008; Vega et al., 2009). The new fossil material from the Miocene Agueguexquite Formation of Veracruz here reported differs from the Chiapas specimens on its more developed, coarser, and 5
compound tubercles, which appear to be finer and simple in the Chiapas specimens (Vega et al., 2008, pl. 1, figs. 7–12; Vega et al., 2009, pl. 1, fig. 11). Based on the coarse granulation with compound tubercles, the Agueguexquite material is most similar to the extant Petrochirus diogenenes (Linnaeus, 1758). The fossil species P. bahamensis (Herbst, 1791), known from upper Pliocene to the upper Pleistocene rocks of Jamaica (Collins and Portell, 1998; Collins et al., 2009; Collins and Donovan, 2012; Luque et al., 2017, fig. 16C), is a junior synonym of P. diogenes (Williams, 1984; R. Lemaitre, pers. comm. to J. Luque, 2018). The fossil material from the Agueguexquite Formation may be conspecific to either Petrochirus diogenes or with P. bouvieri Rathbun, 1918 , known from the upper Miocene to upper Pliocene of Panama, Colombia, and Costa Rica (Toula, 1911; Todd and Collins, 2005; Bermúdez et al., 2017; Luque et al., 2017). However, due to the fragmentary nature of the material here studied, a more precise specific affinity is not possible at this time.
Infraorder Brachyura Latreille, 1802 Section Eubrachyura Saint Laurent, 1980 Subsection Raninoida De Haan, 1839 Superfamily Raninoidea De Haan, 1839 Genus Ranina Lamarck, 1801 Ranina sp. Fig. 5 Description. Carapace incomplete only left anterior third preserved; rostrum trifid, with axial two inner orbital spines, central spine triangular; intra- and outer orbital spines triangular; anterolateral margin with two bifid spines; left merus terraced. 6
Material examined. One specimen, IGM-11457. Measurements (in mm). IGM-11457, maximum length = 30.6; maximum width = 45.3. Remarks. This specimen represents the first record of Ranina from the middle Miocene Tuxpan Formation in Veracruz, and the third putative record of the genus in Mexico (see in Luque et al., 2017). Unfortunately, the Miocene specimen from Veracruz here studied is too fragmentary to allow a precise identification at the species level, until more complete specimens become available.
Subsection Heterotremata Guinot, 1977 Superfamily Aethroidea Dana, 1851 Family Aethridae Dana, 1851 Genus Hepatus Latreille, 1802 Hepatus lineatinus Collins and Todd, in Todd and Collins, 2005 Fig. 6 Description. Carapace wider than long, transversely sub-ovate, wider at posterior third; dorsal carapace smooth in larger specimens, but with regions more inflated in smaller specimens, with metagastric, cardiac, and branchial regions ornamented with transverse rows or clusters of fine granules. Orbito-frontal margin short, nearly one-third the carapace maximum width; rostrum short, wide, weakly bilobed, barely extending beyond orbits; orbits small, sub-ovate, horizontal, slightly directed upwards. Anterolateral margin convex, bearing over a dozen short, tridenticulate spines; posterolateral margin shorter than anterolateral margin, strongly concave, bearing fine, evenly-spaced tubercles; posterior margin slightly convex, about as wide as orbito-frontal margin, and about one-third the carapace maximum width. Sternites 1–4 fused; sternites 1–2 small, triangular; sternite 3 7
sub-triangular, twice as wide as long; contact between sternites 3–4 expressed as a faint trace of the oblique suture; sternite 4 sub-trapezoidal, wider than long; sternites 5 and 7 similar in shape, slightly petaloid, being sternite 5 the widest, and subsequent sternites narrowing posteriorly; sternites 4–7 bearing sub-triangular episternites postero-laterally, with their posterior ends reaching the level of half the height of the sternite posterior to it. Sternal sutures 4/5 to 6/7 mostly incomplete, and only fused axially; sternites 3–7 deeply depressed axially. Articular condyles of pereiopods articulating with gynglimes formed between the lateral expression of a sternite and its episternites. Chelipeds homochelous, short, robust. Dactyli and propodi short, about one-third the length of propodus, subtriangular, slightly curved downwards, tip acute distally; dactylus bearing a few tubercles proximally near junction with propodus. Propodus outer manus about 1.5 times as long as high, bearing several rows of tubercles parallel to the lower margin of propodus, with the most dorsal rows curving; bottom rows extending distally into proximal portion of pollex. Carpus sub-triangular, bearing a few rows of tubercles dorsally. Merus about as long as propodus. Third maxillipeds, when preserved, elongate, operculiform, sub-triangular, and bearing ischium and merus in two planes. Material examined. Six specimens, USNM PAL 770831 to USNM PAL 770836. Measurements (in mm). USNM PAL 770831, length = 35.2; width = 58.3; USNM PAL 770832, length = 31.4; width = 60.2; USNM PAL 770833, length = 31.3; width = 36.5; USNM PAL 770834, length = 19.8; width = 38.3; USNM PAL 770835, length = 22.0; width = 28.3. Remarks. The genera Hepatus and Hepatella Smith, 1869 are very similar to each other, but differ on the broader carapaces that Hepatus has, and the produced rostrum that extends considerably beyond the orbits seen in Hepatella. The new specimens from the 8
Agueguexquite Formation can be referred to Hepatus due to the broader carapace and short rostrum barely extending beyond the orbits (Guinot, 1978; Schweitzer and Feldmann, 2000). More precisely, the new material seem to be conspecific to Hepatus lineatinus; a species known from the Miocene and Pliocene of Panama, Costa Rica, Venezuela, Colombia and Curaçao (Todd and Collins, 2005; Bermúdez et al., 2017; Luque et al., 2017). The Agueguexquite material includes larger specimens with smoother carapaces overall, and smaller individuals with carapaces bearing dorsal regions more inflated and ornamented with coarse and fine tubercles, similar to the type material of H. lineatinus. Although other aethrid crabs have already been reported from the Eocene and Miocene of Mexico (Vega et al., 2001; Schweitzer et al., 2007; Vega et al., 2009; Luque et al., 2017), this is the first record of the genus Hepatus in the fossil record of Mexico.
Superfamily Calappoidea De Haan, 1833 Family Calappidae De Haan, 1833 Genus Calappa Weber, 1795 Calappa sp. Fig. 7 Description. Carapace suboval, widest at midlength, cuticle granulose, carapace defined with five rows of longitudinal tubercles; anterior margin not preserved; lateral margins concave; posterolateral margin also not preserved; left carpus subriangular, granulose. Right palm, much higher at distal portion with serrated dorsal edge bearing five clear spines; curved dactylus; serrated ventral margin and outer margin of dactylus; distal tip of fixed finger sharps and slightly curved upwards.
Material examined. Two specimens, USNM PAL 770837 (dorsal carapace); USNM 496475 (right chela). Measurements (in mm). TU 638-023 length = 29.3; width = 40.2; USNM 496475; maximum length = 45.1; maximum height =28.2. Remarks. To date, only two species of Calappa have been reported from Mexico: C. flamea (Herbst, 1794), from the Oligocene of Baja California, and C. zurcheri Bouvier, 1899, from the Oligocene of Veracruz and the early Miocene of Chiapas (Rathbun, 1930; Vega et al., 2009; Luque et al., 2017). The presence of specimen TU 638-023 in the upper Miocene Agueguexquite Formation (Fig. 7a), and specimen USNM 496475 in the lower Miocene Concepción Formation (Fig. 7b), confirm the presence of the genus in Mexico during the entire Miocene. Unfortunately, the preservation of the specimens is too poor to allow a more precise identification.
Superfamily Leucosioidea Samouelle, 1819 Family Leucosiidae Samouelle, 1819 Subfamily Ebaliinae Stimpson, 1871 Genus Persephona Leach, 1817 Persephona sp. Fig. 8 Description. Carapace, sub-ovate, slightly longer than wide, strongly vaulted, with coarse granulation dorsally and ventrally. Fronto-orbital margin poorly preserved in the studied specimens, apparently much wider than it is long, extending beyond the anterolateral margin. One specimen with part of the left orbit (Fig. 8C) apparently bears two closed orbital fissures. Sub-hepatic region bearing a projection in the form of a blunt tubercle. 10
Lateral margins well defined, marked by aligned granules. Posterior margin much wider than orbito-frontal margin, with three well-developed marginal spines; mesial spine slightly longer than lateral spines; posterior margin of the carapace between the two lateral spines covered with minute granules (Fig. 8A). One female specimen preserves fused sternites 1– 4; sternites 1–2 very small, triangular, fused to a much wider sternite 3, as wide or wider than orbito-frontal margin, with a sub-squarish axial depression where the telson fits (missing in studied specimen, Fig. 8C, D); sternite 4 about five times wider than long, fused with sternite 3; lateral expression of sternites 3 and 4 with marked junction in the form of a depression. Pleon of female with pleonites 1–3 narrow, unfused, and pleonites 4–6 very broad, fused, forming a broad shield that covers most of sternite 4 and completely the sternites 5–8, therefore not visible (Fig. 8D). In the specimens studied, the maxillipeds, telson, and appendicular elements not preserved. Material examined. Two specimens, USNM PAL 770838 and USNM PAL 770839. Measurements (in mm). USNM PAL 770838, length = 24.3, width = 20.2; USNM PAL 770839, length = 25.5, width = 19.9. Remarks. The overall carapace outline and pattern of tuberculation in the fossil leucosiids here reported is reminiscent of Persephona, an extant genus with a fossil record known from the Neogene and Quaternary of the Americas (Luque et al., 2017; Ossó et al., 2018). Another genus that may accommodate the fossils here illustrated is Acanthilia Galil, 2000, a monotypic genus that shares a similar carapace outline with Persephona, yet it is more elongated, has a broader anterior half (D. Felder pers. comm. to J. Luque, 2018), has broader sub-triangular posterior lateral spines, and a longer mesial conical spine than Persephona (Fernández and Lira, 2017). The genus Iliacantha Stimpson, 1871 is in some ways similar to Persephona as well, and at times hard to differentiate from each other, 11
especially among juvenile specimens and if appendicular elements and color patterns are not preserved (Hendrickx, 1997; Ossó et al., 2018). Based on the carapace shape and proportions, the construction of the anterolateral and posterior margins, and the shape and size of the posterior spines of the fossil material here examined, we tentatively assign it to Persephona until new material becomes available to allow a more detailed placement at the genus and species level. The sternal construction of sternites 3–4 seen in the female specimen from Veracruz (Fig. 8C–D) is similar to that of the extant P. punctata (Linnaeus, 1758) in the overall sub-squarish shape of the axial depression in sternite 3 where the telson rests, and the lateral expression of sternites 3 and 4 with a marked junction between both sternites. In females of P. subovata (Rathbun, 1893), the depression on sternite 3 is more elongate and sub-trapezoidal, and the lateral expression of sternites 3 and 4 is less marked than in P. punctata and the specimens from Veracruz. Yet, in the Veracruz fossils, the posterior margin of the carapace between the two lateral spines is covered with minute granules, whereas in Persephona punctata it is lined with more than 12 small but welldeveloped triangular spines, and in P. subovata is lined with about 7 small but conspicuous tubercles (Ossó et al., 2018, fig. 2D). The specimens here reported differ from P. niemeyeri Blow, 2003, and P. rodesae Blow, 2003, from the upper Pliocene Yorktown Formation of southeastern Virginia, in the smoother carapace granulation, lack of thick granules in the lateral margins, with a developed distal tubercle in the sub-hepatic region, and by having more developed posterior spines with no secondary spines or coarse granules in the posterior margin. Similarly, the new Miocene material from the Agueguexquite Formation in Veracruz differs from P. enigmatica Collins and Todd in Todd and Collins, 2005 and P. manningi Collins and Todd in Todd and Collins, 2005 from the upper Pliocene of Costa Rica and Panama, respectively, 12
in lacking the flattened spines in the posterior angles seen in both species, the upturned posterior spines of P. manningi, or the round carapace with a narrower posterior margin seen in P. enigmatica. The material reported by Collins et al. (2014) as P. aquilonaris Rathbun, 1933, from Pleistocene Beaumont Formation in Texas, and by Portell and Agnew (2004) as P. mediterranea (Herbst, 1794) from the Pleistocene of Florida differ from the Veracruz specimens in their roundish carapaces with coarser granulations, the lack of a conspicuous sub-hepatic protuberance, and the well-developed spines or tubercles in the posterior margin between the two lateral spines (Collins et al., 2014, pl. 2, figs 4–5; Luque et al., 2017, pp. 49–50, fig. 14F). The new material from the Agueguexquite Formation represents the first fossil record of Persephona in Mexico, and confirms the wide distribution of the group in the Americas since at least the Miocene (Luque et al., 2017).
Superfamily Portunoidea Rafinesque, 1815 Family Portunidae Rafinesque, 1815 Subfamily Necronectinae Glaessner, 1928 Genus Necronectes A. Milne-Edwards, 1881 Necronectes sp. cf. N. proavitus (Rathbun, 1918) Fig, 9 Description. Incomplete, male large specimen, subhexagonal, preserving only right, voluminous cheliped and remains of P2-P5, dactylus of the last pereiopod, flat and ovate; dorsal cuticle granulate; anterolateral margin with 7 sharp, spines; ventral portion relatively well preserved, subovoid, sternite 2 subrectangular, sternite 3 subtrapezoidal, two times the length and three times the width of sternite 2; sternite 4 wider and inverted subtrapexoidal; 13
sternites 5-7 nearly rectangular, decreasing in size posteriorly; sternite 8 small, triangular; meri from chelipeds to that of P5 preserved, and decreasing in strength and size, backwards. Right third maxillipeds better preserved, subrectangular, elongate endognath with small, triangular coxa and thinner (half the width of endognath) but nearly as long. Material examined. One specimen, IGM-11458. Measurements (in mm). IGM-11458, length = 132.5, width = 138.7 Remarks. Martínez et al (2007) reported Necronectes proavitus (Rathbun, 1918) from the same lower Miocene Tulijá Formation locality, nearby the Chacamax River, where the specimen here reported was collected. Before that, only two other necronectid species were known: N. nodosus Schweitzer, Feldmann, Gonzáles-Barba, and Vega, 2002 from the Oligocene of Baja California Sur, and N. tajinensis Vega, Feldmann, Villalobos-Hiriart, and Gío-Argáez, 1999, from the Middle Miocene of Veracruz, plus a record of Necronectes sp. from the early Miocene of Chiapas (Vega et al., 2009: Luque et al., 2017) and a report of N. proavitus from the early Miocene of Chiapas (Martínez et al., 2007). Although the new specimen is too incomplete to permit a detailed identification, it might be conspecific with either N. proavitus or N. tajinensis. Regardless of its specific affinity, the new specimen represents an important addition to the knowledge of the fossil crustacean fauna from the SE of Mexico.
Subfamily Podophthalminae Dana, 1851 Genus Euphylax Stimpson, 1862a Euphylax sp. aff. E. domingensis (Rathbun, 1919) Fig. 10
Description. Carapace sub-hexagonal, slightly less than twice as wide as it is long, with well-defined anterolateral and posterolateral margins. Orbito-frontal margin very wide, about 90 percent the carapace maximum width. Orbits very wide and deep, about 40 percent as long as the carapace maximum width, and nearly as wide as the length of the posterior margin; supraorbital margin granulated, bearing two orbital fissures near the outer orbital spine; suborbital margin well-developed, coarsely granulated, visible in dorsal view. Rostrum T-shaped, very narrow proximally, about five percent the carapace width or slightly narrower, moderately produced beyond the orbits, and with distal tip broader, about 3 times as wide as the proximal portion. Anterolateral margin shorter than the posterolateral margin, about 20 percent the carapace maximum width, bearing four short triangular anterolateral spines excluding the outer orbital spine. Posterolateral margin about twice as long as the anterolateral margin, and nearly 40 percent the carapace maximum length, slightly convex anteriorly, and nearly straight to slightly concave posteriorly, lacking spines. Posterolateral margin straight to slightly convex, about 40 percent the carapace maximum width, or nearly as wide as the length of posterolateral margin. Dorsal carapace somewhat flattened, finely granulated, bearing a weak transverse ridge on the epibranchial region. Dorsal regions poorly delimited; protogastric region laterally marked by an incipient groove; mesogastric and metagastric regions separated by a moderately developed transverse groove. Sternites 1 and 2 in females fused, small, triangular; sternite 3 much wider than long, sub-trapezoidal, in a different plane than sternites 1–2, weakly concave axially; sternite 4 twice as wide as it is long, sub-hexagonal, depressed anteromesially and with raised posterolateral lobes, axially sulcate, with lateral margins nearly straight; lateral expressions of sternites 5–7 petaloid in shape, much wider than long. Material examined. Six specimens, USNM PAL 770840 to USNM PAL 770845. 15
Measurements (in mm). USNM PAL 770840, length = 40.2, width = 81.4; USNM PAL 770841, length = 30.1, width = 50.1; USNM PAL 770842, length = 30.4, width = 52.5; USNM PAL 770843, length = 33.1, width = 43.1; USNM PAL 770845, length = 30.8, width = 51.3 (USNM PAL 770844 are claw fragments not measured or illustrated). Remarks. The material here studied can be referred to Euphylax based on the presence of four anterolateral spines, transverse carapace ridges, and a narrow proximal rostrum less than 5% the carapace width, compared to the eight anterolateral spines, lack of transverse ridges, and a proximal rostrum about 10% the carapace width diagnostic of Paraeuphylax Varela and Schweitzer, 2011. The new material from the Miocene of Veracruz differs from Euphylax septendentatus Beurlen, 1958, from the Miocene, Pará, Brazil, in lacking the seven anterolateral spines diagnostic of the latter, and from E. fortispinosus Collins, Donovan, Lindsay, and Simpson, 2001, from the lower Pleistocene of Jamaica, in the lack of anterolateral spines as strongly developed as in the latter. Another fossil species, E. maculatus Collins and Todd in Todd and Collins, 2005, is known from the middle-late Miocene to early late Pliocene and early Pleistocene of Costa Rica, Panamá, and Colombia. The type material of Euphylax maculatus was described as having an epibranchial ridge ‘bounded distally by a double row of granules’ (Todd and Collins, 2005, p. 76). These features seem to be absent in the Veracruz material. The anterolateral margin, shape and size of the anterolateral spines, the outer orbital spine, and the shape of the well-developed epibranchial transverse ridge of the Euphylax specimens from Veracruz, are more reminiscent of E. domingensis (Rathbun, 1919), from the Miocene of Cuba and Dominican Republic (Schweitzer et al., 2006; Varela and Rojas-Consuegra, 2011), and less so of E. callinectias Rathbun, 1918  from the Eocene of Peru and the Miocene of Panama and Costa Rica (Todd and Collins, 2005; Luque et al., 2017). The geographic occurrence of the 16
new material also suggests a closer proximity to the Cuban and Dominican species. Therefore, we tentatively assign the Veracruz specimens to E. domingensis. It is possible that the fragmentary and poorly preserved specimens of E. fortis Rathbun, 1918 , from the early Pliocene (not Miocene), of Costa Rica (Todd and Collins, 2005), might belong to E. callinectias. Although fossils of Euphylax are widely known from Central America, northern South America, and the Caribbean (Luque et al., 2017), to our knowledge, this is the first fossil record of the genus in Mexico.
Subfamily Portuninae Rafinesque, 1815 Genus Portunus Weber, 1795 Portunus atecuicitlis Vega, Feldmann, Villalobos.Hiriart and Gío-Argáes, 1999 Fig. 11 Description. Portunid of moderate size; width about 1.5 times the length; gently arched transversely and longitudinally, most tightly arched in posterior half of carapace; front and anterolateral margins form a nearly smooth arch; Front moderate width, about 15 percent carapace width with two short spines on either side of midline; orbits well defined by triangular inner and outer orbital spines; broad, concave beaded margins axially and two orbital fissures situated in lateral third of orbit, near outer orbital spine; anterolateral margin weakly upturned, with at least six approximately equal sized triangular spines, excluding outer orbital spine; last spine apparently not elongated; posterolateral margin smooth, sinuous; slightly convex anteriorly becoming concave posteriorly; posterior margin straight, thickly rimmed, about 38 percent carapace width; carapace regions more distinctly defined on small specimens, not clearly defined on large specimens, only slightly elevated above broad, ill-defined grooves; branchial regions most strongly swollen with broad ridge 17
extending in convex-forward arc from cardiac region to lateral corner; another ridge extends transversely across protogastric and mesogastric regions. Carapace surface with widely spaced granules over entire surface except frontal region which is smooth to very finely pustulose; buccal cavity rectangular, wider than long; maxillipeds do not cover axial portion of cavity; thoracic stemites typical for family, not fused except elements 1-3; anterior half of stemite 4 of male markedly lower than posterior half; sternum widest, about 50 percent carapace width, at stemite 7; telson and at least two abdominal somites of male form broad isosceles triangle, broadest element probably represents fusion of somites 3-5. Proximal abdominal somites reduced, carried in subvertical position; chelipeds greatly elongated and much larger than walking legs; width from one carpus to the other about 1.4 times carapace width; merus triangular in cross section, with at least three spines on inner margin; carpus with prominent spine at inner articulation with merus and nodose prominences at articulations with propodus; propodus long, stout, strongly keeled; three keels on outer surface, two keels terminating in small spines define upper surface; one keel on inner surface; fingers slightly shorter than palm, bearing broad, domal teeth proximally and narrower, sharper teeth distally. Material examined. Four specimens, IGM-11459 to IGM-11462. Measurements (in mm). IGM-11459, length = 47.9, width = 74.8; IGM-11460, length = 47.8, width = 82.5; IGM-11461, length = 52.5, width = 80.1; IGM-11462, length = 34.8, width = 47.9. Remarks. Specimens here reported were found at the same locality reported by Vega et al. (1999) and represent a complement to this apparently abundant species in the middle Miocene Tuxpan Formation, Veracruz, Mexico.
Superfamily Eriphioidea MacLeay, 1838 Family Eriphidae? MacLeay, 1838 Genus Eupilumnus? Kossmann, 1877 Eupilumnus? vokesae Luque, sp. nov. Fig. 12 Diagnosis. Dorsal carapace covered with small granules; branchial ridge absent. Rostrum more than twice the width of the orbits, short, bilobate, deeply sulcate, V-shaped, with two well-developed conical and acute spines projecting forwards, and with two pairs of accessory lateral spines along the lateral margins of rostrum. Dactylus and pollex of right cheliped bearing two rows each of well-developed acute spines. Description. Carapace slightly wider than long, vaulted, sub-circular, markedly granulate dorsally, with distinct anterolateral and posterolateral margins. Anterolateral margins about as long as posterolateral margin, both convex, separated by a short epibranchial spine; anterolateral margin bearing 5-6 spines, each of them trifid in at least one specimen, with the central primary spine longer than the lateral secondary spines; posterolateral margin about as long as anterolateral margin, convex, smooth, lacking spines; posterior margin convex. Orbito-frontal margin about half the width of the carapace maximum width; rostrum more than twice the width of the orbits, short, bilobate, deeply sulcate, V-shaped, with two well-developed conical and acute spines projecting forwards, and with two pairs of accessory lateral spines along the lateral margins of rostrum; orbits slightly upturned, with a well-developed intra-orbital spine and a single, acute outer orbital spine. Both specimens studied are heterochelous, having right chelipeds slightly larger and more robust than the left chelipeds. Cheliped outer margins ornamented with coarse, short tubercles, and with cuticle of dactylus and propodus covered with small pores, not seen when cuticle is 19
decorticated. Outer manus of the right cheliped bears six rows of short, acute spines evenly spaced from each other; lower margin of pollex of propodus with two rows bearing multiple coarse and acute spines extending close to the tip and decreasing in size distally; occlusal surface of pollex armed with 3 thick, molariform teeth, a smaller tooth distally, and a short, blunt distal tip; dactylus of right cheliped short and robust, similar to pollex, also with four short and wide blunt teeth, and a short, blunt tip. Etymology. The species name honors Emily H. Vokes, a prominent invertebrate paleontologist who has worked extensively in the Americas, including Mexico, and who discovered and collected the fossils here studied. Material examined. Holotype USNM PAL 770846 and paratype USNM PAL 770847. Measurements (in mm). Holotype USNM PAL 770846, length =22.5, width = 20.2; paratype USNM PAL 770847, length =13.4, width= 32.1. Remarks. The new specimens here studied are unlike any fossil crab species discovered in the Americas so far (Luque et al., 2017). Based solely on features preserved on the dorsal carapaces and chelipeds of the holotype and paratype, the new species resembles Pilumnoididae Guinot and Macpherson, 1987; a family of puzzling heterotreme crabs currently included within the superfamily Pseudozioidea Alcock, 1898 (Ng et al., 2008). Pilumnoididae, as currently envisioned, is a monogeneric family constituted by 8 extant species all in the genus Pilumnoides Lucas, in H. Milne Edwards and Lucas, 1844, and are distributed mainly along the Pacific and Atlantic/Caribbean coasts of the Americas, the west coast of Africa, and an occurrence in England (Guinot and Macpherson, 1987). Some of the most diagnostic anatomical features in Pilumnoides are sternal (Guinot and Macpherson, 1987). Unfortunately, it is unclear if the fossils here studied preserve the sternum, as the ventral sides are still covered with matrix and are not available for 20
preparation at the moment. Furthermore, they are decorticated to different extents, which hinders the interpretation of the dorsal ornamentation. Based on the type material alone, the granulation and tuberculation patterns on the dorsal carapace of Eupilumnus? vokesae sp. nov. is similar to that of the extant P. rotundus Garth, 1940, from the Pacific coast of the Neotropics, from Mexico to Peru (Guinot and Macpherson, 1987, fig. 3, pl. 1J-K). Eupilumnus? vokesae sp. nov. shares with P. rotundus and P. nudifrons Stimpson, 1871, the latter known from the Caribbean region, the lack of branchial ridges, which are present in the rest of the Pilumnoides species (Guinot and Macpherson, 1987, p. 215). However, E. vokesae sp. nov. differs from P. rotundus in the coarsely granulated chelipeds with welldeveloped long spines on the outer margin of the manus, pollex, and dactyl seen in the new species. The new species differs from any of the known extant species of Pilumnoides on its short, bilobate, and deeply sulcate V-shaped front, with two well-developed conical and acute spines projecting forwards, and with two pairs of accessory lateral spines along the lateral margins of rostrum (Fig. 12A,C,D; compare with Guinot and Macpherson, 1987, fig. 4). The only species of Pilumnoides with a somewhat projected rostral margins is P. coelhoi Guinot and Macpherson, 1987, from the southwest Atlantic (Brazil), but the latter has a U-shaped median sulcus instead of V-shaped, and lacks the distinctive projecting acute spines seen in E. vokesae sp. nov. Besides Pilumnoides, the only other genus currently included in the family Pilumnoididae is Setozius Ng and Ahyong, 2013, comprised by the extant species S. incertus Ng and Ahyong, 2013, from the West Pacific, and S. ikeharai Naruse and Maenosono, 2019, from Japan. These species differ from E. vokesae n. sp. in their less protruded bilobed frontal margin that is either smooth (i.e., S. ikeharai) or bears four small tubercles (i.e., S. incertus), instead of long projecting conical spines. Moreover, the shape, 21
size, and configuration of their single anterolateral spines also contrast with the composite spines seen in E. vokesae n. sp. It is very possible that the new species may also belong to Pilumnidae Samouelle, 1819 (superfamily Pilumnoidea Samouelle, 1819), and be closer to genera like Lophopilumnus Miers, 1886, or Pilumnus Pilumnus Leach, 1816, but the overall configuration of the dorsal regions and the construction of the rostrum of the new species do not seem to match. On the other hand, the overall resemblance of the new species with some crabs of the genus Eupilumnus (superfamily Eriphioidea) suggests a possible affinity with the group. Unfortunately, as with the other taxa above discussed, the decorticated nature of the studied fossils and their unknown ventral carapace make a more direct comparison problematic. The genus Eupilumnus includes nine extant species distributed mainly across the Indo-Pacific, the Persian Gulf, and West Africa (information retrieved from World Register of Marine Species WoRMS http://www.marinespecies.org/, March 2nd, 2020). The only American species of Eupilumnus yet discovered is E. xanthusii (Stimpson, 1860), found along the Eastern Pacific from Baja California, Mexico, down to Costa Rica, Colombia, and Ecuador including the Galapagos (e.g., Pereyra, 1998; Hernandez et al., 2013). Eupilumnus? vokesae n. sp. differs from the latter on its diagnostic short, bilobate, and deeply sulcate V-shaped front bearing well-developed conical and acute spines projecting forwards, and its compound, trifurcating anterolateral spines (compare with Rathbun, 1930b, for example). Phylogenetic studies have found that the Eupilumnus is not a monophyletic genus and that the genus is in need of a revision (Lai et al., 2014). We agree. The range of similar, convergent body forms seen across eriphioid, pseudozioid, and pilumnoid crabs may lead to long branch attractions, further obscuring the systematic relationships across highly derived and fast evolving clades. 22
Due to the incompleteness of the fossil material here studied, we tentatively include the new species within Eupilumnus, although it is quite possible that it belongs to a similar extant genus, or even to its own new genus. We hope that future preparation of the ventral region of the studied fossils, or their imaging using digital scanning reconstructions, will reveal additional anatomical features to better assess the systematic placement of the new species.
Superfamily Xanthoidea MacLeay, 1838? Family Panopeidae Ortmann, 1893 Genus Eurytium Stimpson, 1862b Eurythium granulosus Schweitzer, Velez-Juarbe, Martinez, Collmar-Hull, Feldmann, and Santos, 2008. Eurytium granulosus Schweitzer, Velez-Juarbe et al., 2008, p. 9, fig. 5.1, 5.2. Fig. 13 Description. Carapace of medium size, subhexagonal, wider than long, widest at midlength; cuticle with granules of uniform size; anterior margin two-thirds maximum width, orbits semicircular, small, rimmed, front subrectangular, projected beyond orbits, with median groove; anterolateral margin concave, half the length of carapace, with four short, triangular spines; posterolateral margin slightly concave, half the length of carapace; posterior margin straight, narrow, one-third carapace width; protogastric region invertedsubtriangular; mesogastric region subpentagonal, with a narrow process that extends only to base of rostrum; urogatric region depressed, narrow; cardiac region subtrapezoidal; mesobranchial region semioval, inclined; metabranchial region a raised platform; cervical groove deeply impressed; sternite 2 subtrapezoidal, sternite 3 subrectangular; male 23
abdomen narrow, wider at base of telson; somites 4 and 5 fused in a elongate rectangle; somite 3 subtrapezoidal; right chela larger than left; right carpus robust, subrhombic in dorsal view; right palm elongate, subrectangular, covered by small granules; left palm also elongate, rectangular; left fixed finger triangular, pigmented, with three broad triangular teeth on occlusal surface; movable finger triangular, downturned, tip sharp, pigmented, with one large and three smaller teeth toward the tip. Material examined. Four nearly complete specimens, USNM PAL 770848, USNM PAL 770849, USNM PAL 770850 and USNM PAL 770851. Measurements (in mm). USNM PAL 770848, length = 19.3, width = 34.1; USNM PAL 770849, length = 22.4, width = 31.6; length = 19.3, width = 34.1; USNM PAL 770850, length = 25.4, width = 30.5; USNM PAL 770851, length = 29.8, width = 32.4. Remarks. Eurityum sp. was reported from the lower Miocene Macuspana Limestone and the mid-upper Miocene Agueguexquite Formation of Tabasco and Veracruz, respectively (Vega et al., 2009). The preservation of the specimens found by Emily H. Vokes in 1963 and here illustrated are much better preserved and now can be compared with E. granulosum from the Miocene Ponce Limestone of Puerto Rico (Schweitzer et al., 2008).
5. Discussion/Conclusions A new species, Eupilumnus vokesae, is unlike any fossil crab species previously known from the Americas. Its overall anatomy is somewhat reminiscent of some crabs in the families Pilumnoididae (Pseudozioidea), Pilumnidae (Pilumnoidea) and Eriphidae (Eriphioidea). The presence of Eupilumnus? vokesae sp. nov. in the Miocene Agueguexquite Formation in Veracruz, Mexico, would represent the oldest and only fossil record of the genus known to date, thus extending its record into the mid-Miocene. 24
However, it is quite possible that it belongs to a similar extant genus of another family, or even to its own new genus. The occurrences of Hepatus lineatinus (Aethridae), Persephona sp. (Ebaliidae), and Euphylax domingensis (Portunidae: Podophthalminae) in the upper Miocene Agueguexquite Formation represent the first fossil record of these genera in Mexico. Besides these records, the new fossil material of Necronectes (Portunidae: Necronectinae) from the lower Miocene Tulijá Formation, Ranina (Raninidae) and Portunus (Portunidae: Portuninae) from the middle Miocene Tuxpan Formation, Calappa (Calappidae) from the lower Miocene Concepción Formation and upper Miocene Agueguexquite Formation, Petrochirus (Diogenidae) and Eurityum (Xanthidae) from the upper Miocene Agueguexquite Formation, Veracruz), confirm the wide distribution of these genera in the Americas during the Miocene (see Vega et al., 1999; 2009; Luque et al., 2017 for geographic and stratigraphic details of these occurrences). The age range of the studied decapod crustacean material support an upper Miocene age for the Agueguexquite Formation, as previously suggested by isotopic stratigraphy and nannoplankton biostratigraphy (Pineda-Salgado et al., 2016).
Acknowledgements Our sincere thanks to Rodney M. Feldmann (Kent State University, Kent, Ohio) and an anonymous reviewer for their kind suggestions to improve the original manuscript. We also wish to thank Mark Florence and Conrad Labandeira (Invertebrate Paleontology, Paleobiology Department, Smithsonian Institute National Museum of Natural History USNM, Washington, D.C., USA) for help facilitating access to the collections, and to Susan Butts and Jessica B. Utrup (Yale Peabody Museum of Natural History, Invertebrate 25
Paleontology) for help with loans and photographs, respectively; to Rafael Lemaitre (Smithsonian Institute National Museum of Natural History USNM, Washington, D.C., USA) and Darryl Felder (Department of Biology, University of Louisiana at Lafayette, Louisiana, USA) for valuable discussions about the fossil pagurid and leucosiid here studied, respectively; to Àlex Ossó, Jose Luís Dominguez, Steven Campbell, and Ondřej Radosta for valuable discussions about the systematic placement of the new fossil crab species here described. JL thanks Derek E.G. Briggs (Yale University, USA), Yale Institute for Biological Studies (YIBS), and the Natural Sciences and Engineering Research Council of Canada (NSERC) Postdoctoral Fellowship, for their support. FV wants to thank Dirección General de Apoyo al Personal Académico, UNAM, for support via project PAPIIT- IN107617.
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Figure captions Fig. 1. Location, based on geological map of Servicio Geológico Mexicano, Carta Geológica-Minera Coatzacoalcos (2004), of the three localities where specimens here described were collected by Emily H Vokes in 1963.
Fig. 2. Field views of outcrops of locality TU-1025, covered by vegetation and the scarce outcrops of the upper Miocene Agueguexquite Formation are now all weathered.
Fig. 3. Composed stratigraphic section of lithostratigraphic units cropping out east of Coatzacoalcos and relative position of the main three localities here reported: TU-638, TU1025 and TU-1046. Note isotopic age assigned to main localities of the Agueguexquite Formation (8.8 My).
Fig. 4. Petrochirus sp. USNM PAL 770829 (A, both chelipeds partially preserved), locality TU-1046; USNM PAL 770830 (B, only palm and fixed finger), locality TU-638. Upper Miocene Agueguexquite Formation, Veracruz. Scale bars = 10 mm.
Fig. 5. Ranina sp. IGM-1457 (A, B, partial front view and stereo reconstruction), locality highway near Poza Rica. Lower Miocene Tuxpan Formation, Veracruz. Scale bars = 10 mm.
Fig. 6. Hepatus lineatinus Collins and Todd, in Todd and Collins, 2005, locality TU 638. USNM PAL 770831 (A, E, dorsal and ventral views); USNM PAL 770832 (B, dorsal view); USNM PAL 770836 (C, D, dorsal and frontal views); USNM PAL 770835 (F–H, 36
dorsal, frontal and ventral views) locality TU 638. Upper Miocene Agueguexquite Formation, Veracruz. Scale bars = 10 mm.
Fig. 7. Calappa sp. USNM PAL 770837 (A, dorsal carapace view), locality TU 638; USNM 496475 (B, right chela), locality indet. Upper Miocene Agueguexquite Formation, Veracruz. Scale bars = 10 mm.
Fig. 8. Persephona sp. USNM PAL 770838 (A, C, D, dorsal, frontal and ventral views), locality TU 638; USNM PAL 770839 (B, dorsal view), locality TU 638. Upper Miocene Agueguexquite Formation, Veracruz. Scale bars = 10 mm.
Fig. 9. Necronectes sp. cf. N. proavitus (Ratbbun, 1918). IGM-11458 (A, B, dorsal and ventral views), locality Chacamax River. Lower Miocene Tulijá Formation, Chiapas. Scale bars = 10 mm.
Fig. 10. Euphylax sp. aff. E. domingensis (Ratbbun, 1919). USNM PAL 770841 (A, B, dorsal and frontal views); USNM PAL 770842 (C–E frontal, dorsal and ventral views); USNM PAL 770845 (F, dorsal view); USNM PAL 770840 (G, dorsal view); USNM PAL 770843 (H, I, dorsal and ventral views), locality TU 638. Upper Miocene Agueguexquite Formation, Veracruz. Scale bars = 10 mm.
Fig. 11. Portunus atecuicitlis Vega, Feldmann, Villalobos.Hiriart and Gío-Argáes, 1999. IGM-11459 to IGM-11462 (A-F, dorsal and ventral views: G, ventral view). Locality on highway near Poza Rica. Lower Miocene Tuxpan Formation, Veracruz. Scale bars = 10 37
Fig. 12. Eupilumnus? vokesae Luque, sp. nov. Holotype USNM PAL 770846 (A–C, E, dorsal, frontal, right anterolateral margin, front close-up, front of carapace, right chela views); paratype USNM PAL 770847 (D, F, G, H, front close-up, right cheliped, details, right cheliped oblique view, both chelipeds in frontal view); locality TU 1046. Upper Miocene Agueguexquite Formation, Veracruz. Scale bars = 10 mm.
Fig. 13. Eurytium granulosus USNM PAL 770851 (A–C, frontal, dorsal and ventral views, male), locality TU 1046; USNM PAL 770849 (D, E, dorsal and ventral views, male), locality TU 638. Upper Miocene Agueguexquite Formation, Veracruz. Scale bars = 10 mm.
Collection of decapod crustaceans collected 60 years ago is finally reported from Mexico. The age of the main fossiliferous lithostratigraphic unit (Agueguexquite Formation) is defined. Not many new taxa are reported but an affinity to the once called Miocene Gatunian Province, is confirmed. Finally, this report represents an important addition to the knowledge of the diverse crustacean fossil fauna from Mexico.
March 5, 2020.
Dr. Andrés Folguera Editor-in-Chief Journal of South American Earth Sciences Dear Dr. Folguera: On behalf of my coauthors and myself, I would like to state that there is no conflict of interest with any person or institution regarding this contribution. With my best wishes, Francisco J. Vega Instituto de Geología Universidad Nacional Autónoma de México Mexico City 04510 Mexico
March 5, 2020.
Dr. Andrés Folguera Editor-in-Chief Journal of South American Earth Sciences Dear Dr. Folguera: On behalf of my coauthors and myself, I would like to state that this is an original contribution and there was not financement for iys development, and the few contributions given from my university are ackowledged as weell as the aid of the reviewers. With my best wishes, Francisco J. Vega Instituto de Geología Universidad Nacional Autónoma de México Mexico City 04510 Mexico