Prebranchioplax cretacica, Vega & Ahyong, 2021

Vega, Francisco & Ahyong, Shane T., 2021, Validation of Prebranchioplax cretacica Vega & Ahyong, a fossil mathildellid crab from the Upper Cretaceous of northeast Mexico (Crustacea: Decapoda: Goneplacoidea), Zootaxa 5004 (3), pp. 498-500 : 498-500

Prebranchioplax cretacica sp. nov.

( Fig. 1 )

Mathildellidae .— Vega et al. 2016: 310, fig. 5D–L.— Vega 2017: 215, fig. 18.8–10.

Prebranchioplax cretacica Vega & Ahyong in Vega et al. 2018: 66–70, figs. 3.1–13, 4.1–16, 5.1 [unavailable].

Type material. HOLOTYPE: CPC-2075, carapace and partial remains of sternum and abdomen, carapace length 19.8 mm, carapace width 20.3 mm, Cerro del Pueblo Entronque . PARATYPES: CPC-2076–CPC-2092, CPC-2100, 18 carapaces, two with remains of sternum and abdomen ( Table 1).

Diagnosis. Carapace subhexagonal, slightly wider than long, front produced, broad, subrectangular with shallow median notch; triangular orbital spines; orbits relatively small, two upper orbital fissures, one suborbital fissure; eyes short, stalked; anterolateral margins convex, bearing four anteriorly projected spines, becoming weaker towards median portion of carapace; posterolateral margin weakly convex, converging posteriorly; posterior margin rimmed with fine tubercles, its width about half maximum carapace width; dorsal cuticle finely granulose, concentric calcification centers; regions distinct, epigastric process strongly marked, mesogastric region wide, ovate; cardiac region rhomboidal, with two small tubercles; intestinal region indistinct; hepatic region indistinct; mesobranchial region subrectangular, inclined towards base of metagastric region where muscle scars evident; metabranchial region transverse, slightly swollen; cervical groove relatively deep, arising from lateral margin between anterolateral spines 2 and 3. Thoracic sternum subpentagonal, sternite 3 triangular inverted, sternite 4 subtrapezoidal; sternite 5 and 6 subrectangular, sternite 7 and 8 subtriangular, episternal processes triangular inverted, sharp. Abdomen triangular, somites free, somites 3–5 short, subrectangular, somite 3 wider than other preserved somites; somite 6 subtrapezoidal, twice length of preceding sternite, telson triangular. Coxa of chelipeds short, concave; no other parts of chelipeds or walking legs preserved.

Etymology. Alluding to the Late Cretaceous age of the new species.

Remarks. A full description and figures of Prebranchioplax cretacica and stratigraphic account are given by Vega et al. (2018).

Figures

FIGURE 1. Prebranchioplax cretacica gen. et sp. nov., holotype, CPC-2075, Entronque, late Campanian Cerro del Pueblo Formation:A, carapace, dorsal view; B, anterior thoracic sternites and abdomen, ventral view. Abbreviations: t = telson; a4–5 = abdominal somites 4–5, respectively; st4–5, thoracic sternites 4–5, respectively. Scale = 10 mm.