Lobithelphusa Rodriguez, 1982

Villalobos-Hiriart, José Luis, Kamanli, Seyit A., Álvarez, Fernando, Garbout, Amin & Clark, Paul F., 2019, Lobithelphusa mexicana Rodriguez, 1982 (Decapoda: Pseudothelphusidae): a reassessment of key characters and systematics, Zootaxa 4586 (1), pp. 151-161 : 152

Genus Lobithelphusa Rodriguez, 1982

Diagnosis. Carapace with flat dorsal surface, regions distinct, median groove shallow, lateral margin granulated ( Fig. 1a ). Third maxilliped with merus of endopod subrectangular, wider than long, anterior border straight, lateral border slightly rounded; ischium trapezoidal, distal half widening; length of exopod half that of ischium ( Fig. 1 b– d). Male G1 of uniform thickness along its length, caudo-cephalically compressed; distal elements well developed. In mesial view ( Fig. 2a ), mesial surface ending distally in prominent, spinulous distal lobe (mdl) and a subdistal acute, triangular spine (mssp), cephalomesially directed. Oval gap (og) forming between distal lobe and subdistal spine. In lateral view ( Fig. 2b ), surface of gonopod smooth, middle portion slightly constricted and standing out as wide, rounded rib; distal half punctate, ending apically in shoulder (lsh) next to rounded lateral crest (lc) of apical cavity. Lateral crest extending on the distal fourth of the cephalic surface to end in two conical, stout, acute spines (lsp), separated by a wide V-shaped notch, larger cephalically and the smaller laterally oriented; caudal portion of lateral crest with hook-shaped apical notch (an). Mesial spinulous distal lobe, partially visible. In cephalic view ( Fig. 2c ), gonopod strong, principal axis with proximal half slightly widening towards the base, with elongate vertical groove (vgr), moderately deep and with parallel margins; distal half broadened by the subapical lateral expansion (lex) widened curved (lateral lobe of Rodriguez, 1982). Mesial distal lobe armed with sharp spines, terminated in acute form and with somewhat larger spines. Lateral crest (lc) of the apical cavity smooth, high, wide, rounded and extending on cephalic surface to end in conical spine, acute and strong, lying between subdistal spine of mesial surface and conical lateral spine, slightly curved proximally. Vertical oval gap between mesial lobe and subdistal three spines, slender and coarsely ovoid, evidently separating lateral and mesial apical surfaces of gonopod, continuing distally to form internal borders of apical cavity. Latero-distal shoulder partially visible. In caudal view ( Fig. 2d ), distal third slightly inclined mesially. Marginal plate (mpl) straight proximally, without row of proximal setae, curved and wider distally; distal mesial angle projected over mesial surface; distal margin concave, forming caudal edge of the apical cavity. Marginal suture arched; lateral suture evident along proximal half of marginal plate, fused with lateral surface along distal half. Subapical lateral expansion broadly curved; disto-lateral shoulder evident. Spinulous distal lobe of mesial surface and subdistal spine triangular, both partially visible. Caudal portion of disto-lateral crest high, with broad, rounded border. Apical cavity (ac) irregular, roughly oval-shaped, oriented caudo-cephalically, with spinules on internal surface of lateral crest; mesial crest rounded; cephalically, inner surface of mesial spinulous lobe above lateral crest; latero-caudal portion continued as apical notch of lateral crest.

Figures

FIGURE 1. Lobithelphusa mexicana, male holotype, NHMUK 1860.23. Carapace: dorsal surface, a; frontal portion, b; lateroventral surface, c; ventral surface, d. Larger chela: internal surface, e; external surface, f.

FIGURE 2. Lobithelphusa mexicana, male holotype, NHMUK 1860.23. First gonopod, a–d: mesial view, a; lateral view, b; cephalic view, c; caudal view, d. Abbreviations: ac, apical cavity; an, apical notch; lc, lateral crest; lex, lateral expansion; lsp, lateral spines; lsh, lateral shoulder; mdl, mesial distal lobe; mpl, marginal plate; mssp, mesial subdistal spine; og, oval gap; vgr, vertical groove.