Vegaranina, Van Bakel & Guinot & Artal & Fraaije & Jagt, 2012

Van Bakel, Barry W. M., Guinot, Danièle, Artal, Pedro, Fraaije, René H. B. & Jagt, John W. M., 2012, A revision of the Palaeocorystoidea and the phylogeny of raninoidian crabs (Crustacea, Decapoda, Brachyura, Podotremata) 3215, Zootaxa 3215 (1), pp. 1-216 : 95-100

Genus Vegaranina n. gen.

Type species. Lophoranina precocious Feldmann, Vega, Tucker, García-Barrera & Avendaño, 1996 , by present designation.

Diagnosis. Carapace large, convex transversely, widest one-quarter from front; rostrum tridentate; orbital margins wide, with 2 notches; anterolateral margin short, with 3 strong spines (excluding extraorbital tooth); long, nonterraced post-frontal region; few (6–8) strong terraces, broadly V-shaped, complete from side to side, posterior to branchiocardiac grooves; lobed terraces anterior of branchiocardiac grooves; terraces finely spinulate; branchiocardiac grooves extended, strongly divergent anteriorly. Pterygostome with few short terraces. Mxp3 expod, endopod elongated, smooth. Sternite 3 crown shaped; sternite 4 wide anteriorly, with junction sternum-pterygostome, episternite 4 small; sternite 5 with large lateral expansions, leading to junction sternum-exposed pleurites; sternites 5, 6 with medial line; sternite 6 narrow. Pleurites 5‒7 partially exposed (gymnopleurity), excavated.

Species included. Vegaranina precocia and Vegaranina sp.

Derivation of name. In honour of Francisco J. Vega, in recognition of his valuable work on fossil decapods from Mexico. Gender feminine.

Remarks. Vegaranina precocia n. comb. is known from the lower Maastrichtian of southeastern Mexico ( Feldmann et al. 1996: 297, figs. 3.1–3.3, 4.1, 4.2) and from the Campanian–Maastrichtian of Cuba ( Varela & Rojas-Consuegra 2009: 119, fig. 1A), whereas V. cf. precocia was recorded from the lower upper Maastrichtian of Puerto Rico ( Schweitzer et al. 2008, p. 5, fig. 3). An unnamed species of the new genus has recently been found in the MNHN collections ( Fig. 28A–C ) but with an undoubtedly erroneous label so that locality and provenance remain unknown). The presence of the genus in Europe is documented by a specimen of another unnamed species from the Maastrichtian of southern France that was examined but is currently in private hands and not available for study.

Vegaranina n. gen. differs from Lophoranina in having three anterolateral spines (two in Lophoranina ); a longer, non-ridged, post-frontal region; fewer terraces posterior to the branchiocardiac grooves (only 6–8 terraces), which are stronger, more V-shaped and complete from side to side; lobed terraces anterior of the branchiocardiac grooves, and branchiocardiac grooves that are extended and strongly divergent anteriorly, instead of being similarly arched anteriorly and posteriorly in Lophoranina .

Lophoraninella was included in Galatheoidea by Schweitzer et al. (2003b: 890) based upon an examination of the holotype (MB.A.229a, b; equivalent to k123a, b) of Ranina cretacea Dames, 1886 . This taxonomic placement was adopted by De Grave et al. (2009: 24), Schweitzer et al. (2010: 50) and Ahyong et al. (2010: 59). Glaessner (1945) erected Lophoraninella for a specimen in the NHM collections (NHM I. 4553, Fig. 30D ) after examination of Dames’s holotype. The NHM specimen was re-examined, the holotype and paratypes photographed ( Fig. 30A– D ), and there is no doubt that this material is conspecific and represents a raninid crab, rather than a galatheoid anomuran. The preservation of the type material may cause confusion because the specimens are preserved in dorsal aspect, compacted, and parts of the carapace have collapsed, exposing remains of the ventral side. Both specimens show parts of the pterygostome and the outline of the buccal frame fairly clearly; the paratype shows the posterior part of the thoracic sternum ( Fig. 30C ). The NHM specimen represents a crushed carapace with frontal aspect preserved ( Fig. 30D ). Lophoraninella differs from Vegaranina n. gen. in having more terraces on the posterior carapace; terraces are finer and straighter; less divergent branchiocardiac grooves; two, rather than three, anterolateral spines (excluding the extraorbital tooth), which are much weaker; a rectangular or subtrapezoidal front, instead of a tridentate front; and a scabraous rather than smooth post-frontal region.

It appears that Vegaranina n. gen. (Campanian–Maastrichtian) links the older Lophoraninella (Cenomanian of Lebanon) to the widely distributed Cenozoic (Eocene–Oligocene) Lophoranina .

Subfamily Raninoidinae L ő renthey in L ő renthey & Beurlen, 1929

Raninoidinae Lőrenthey in Lőrenthey & Beurlen, 1929: 299.

Genera included. Bicornisranina Nyborg & Fam, 2008 , Cristafrons Feldmann, Tshudy & Thomson, 1993 , Notopoides Henderson, 1888 , Notosceles Bourne, 1922b , Pseudorogueus Fraaye, 1995 , Quasilaeviranina Tucker, 1998 , and Raninoides H. Milne Edwards, 1837 .

Diagnosis. Carapace longer than wide, oblong-ovate, urn shaped or lateral margins nearly parallel or tapering posteriorly. Dorsal surface punctate-granular or smooth, polished; post-frontal transverse demarcation may be present, diversely ornamented; grooves indistinct, cervical groove may be present ( Cristafrons ). Anterolateral margin unarmed, or with single spine, may be highly produced, bifurcate or spinose. Rostrum pointed, triangular or trilobate/tridentate, may be carinate. Orbitofrontal margin equal to or greater than half carapace width. Supraorbital margin spinose with medial tooth between 2 fissures, which may be deep, long.

Ocular peduncle folded longitudinally, long, exposed, composed of 2 articles, basophthalmite small, podophthalmite basally inflated, narrowing at tip. Antennules, antennae modified in relation with respiratory currents. Antennule: basal article expanded, may have distal flabelliform lobe, concave internally. Poepistome rather developed, may be medially carinate. Antenna: inserted somewhat below antennule, inclined inwards, short, thick; article 1 with triangular apex directed forwards, urinal opening placed to its dorsal side; articles 2, 3 fused but with suture still distinct; article 3 much better developed, with greatly developed lobe (‘crest’) projecting forwards as far as article 4, forming ventral, internal walls of orbital cavity; article 4 flabelliform, with concave internal surface; article 5 small; flagellum fairly well developed.

Epistome triangular, not prominently produced forwards. Subantennary lobe of pterygostome developed, widened anteriorly. Mxp3 elongated, operculiform; merus rather short, little more than half ischium length. Pleurites 5–7 largely exposed, forming excavated area, overhung by the edge of the branchiostegite, being a water-passage for inhalant respiratory current ( Notopoides , Notosceles ), or area not excavated, not overhung by branchiostegite ( Raninoides ).

Sternum/pterygostome junction developed; sternum/exposed pleurites connection wide between P1, P2, wider, may be distinctly developed between P2, P3. Thoracic sternum with sternites 3–6 forming long, flat shield, strongly deflected at different levels; sternite 3 variously crown shaped; sternite 4 much enlarged, flat, anterior part variously expanded laterally; sutures 4/5 variously oblique, prolonged laterally; sternite 5 with foliaceous or acute expansions; sternite 6 as 2 unequal parts: anterior in the form of widely exposed, long plate, posterior short, linear; sternite 7 slighty wider, markedly bent; sternite 8 perpendicular to sternite 7, saddle shaped. Medial line along sternites 5‒8. Small spermathecal apertures located in tilted posterior part of sternal plate, lying at the bottom of deep, pit-like depression.

Chelipeds homochelous, homodontous; sometimes slender; basis-ischium immoveably fused with long merus. Propodus flattened, upper margin with double carina or only spine on dorsal border; lower margin with few or several sharp spines; both fingers long, sharp; dactylus bent against anterior border of palm, may largely exceed fixed finger length in dimorphic males, unarmed, prehensile border smooth; fixed finger broad with prehensile border armed with several developed teeth.

P2‒P4 moderately stout. Merus long; carpus may be carinated; both propodus, dactylus flattened, compressed; propodus short, enlarged, dactylus variously modified, acute or variously sickle shaped. P4 coxa subdorsally located. P5 more dorsal, strongly or slightly reduced, thus distinct from preceding ones, always applied alongside carapace posterolateral borders; carpus, propodus about same size, small, widened; propodus rounded; dactylus rather small, flattened oval, weakly sickle shaped.

Absence of sterno-abdominal depression. Abdomen short, extremity only reaching level of P4 or P3, freely articulated, 6 articles plus telson, only distally flexed, first 4 articles dorsal; proximal articles wide, as broad as or narrower than posterior margin of carapace. Abdomen not much enlarged in female. Sexual dimorphism relatively indistinct with regard to shape, size. No abdominal locking mechanism.

Presence of posterior branchial orifices, variously developed, may be large, functioning as as inhalant passages ( Raninoides , Notopoides , Notosceles ).

Remarks. Lőrenthey in Lőrenthey & Beurlen (1929: 299) created Raninoidinae to accommodate Raninoides , Notopella , Pseudoraninella , Ranidina , Raninellopsis , Tribolocephalus and Lyreidus , as opposed to both Palaeocorystinae and Ranininae . Guinot (1993b: 1327) revived Raninoidinae . Tucker (1998: 334) erred in noting ‘ Raninoidinae De Haan, 1841: 136–137’. Guinot (1993b) assigned the following extant genera to the subfamily Raninoidinae : Raninoides , Notosceles and Notopoides ; Tucker (1998, fig. 22) added the fossil taxa Carinaranina [= the lyreidid Macroacaena ; see above], Quasilaeviranina , Laeviranina, and Cristafrons . De Grave et al. (2009: 29) and Schweitzer et al. (2010: 75) also included Cenocorystes , originally referred to the Palaeocorystinae by Collins & Breton (2009: 45), which is incorrect (see above, under Cenocorystes ).

The carapace outline is long, oblong-ovate, urn shaped as in Notopoides latus (see Dawson & Yaldwyn 2002), or has near-parallel lateral margins, tapering posteriorly as in the ‘boat-shaped’ Raninoides benedicti . The axial skeleton shows the typical and unique arrangement of raninoids ( Guinot & Quenette 2005: fig. 26B). The medial line is long, extending on to sternites 5‒8 ( Guinot 1993b: fig. 5; Guinot & Quenette 2005: 314, fig. 26A). For the diverse shapes of the crown-shaped anterior sternites and sternites 4‒6, see Chopra (1933: fig. 1).

Figures

FIGURE 28. Vegaranina n. gen. (Raninidae, Ranininae), MNHN R03385 (indeterminate sex); stratigraphic age and provenance unknown; A, dorsal view of carapace; B, ventral view showing thoracic sternum; C, right lateral view showing exposed pleurites. pl5, pl6, pl7, exposed pleurites 5, 6, 7. Scale bars: 10mm.

FIGURE 30. Lophoraninella cretacea (Dames, 1886) (Raninidae, Ranininae), Cenomanian, Hakel (Lebanon); A, B, MB.A229a, b (= k123a, b, holotype; indeterminate sex), dorsal view in normal aspect and counterpart; C, MB.A230a (= k124a, paratype; indeterminate sex) in dorsal view; D, NHM I. 4553 (indeterminate sex), crushed carapace in dorsal view (photographs A–C by C. Neumann, Museum für Naturkunde, Berlin). f, front; pt, pterygostome; ts, thoracic sternum. Scale bars: 5mm.