Dynomeninae Ortmann, 1892

Guinot, Danièle, 2008, A re-evaluation of the Dynomenidae Ortmann, 1892 (Crustacea, Decapoda, Brachyura, Podotremata), with the recognition of four subfamilies, Zootaxa 1850, pp. 1-26 : 8-10

Dynomeninae Ortmann, 1892

( Figures 1 D, 3C, D, 4A–C, E, 5A–H)

Type genus. Dynomene Desmarest, 1823 ( Cancer hispida Latreille, 1812 : type species by monotypy by subsequent designation of H. Milne Edwards, 1837: 180; ICZN 1999, Art. 67.2.2).

The authorship of Dynomene hispida , usually credited to Guérin or Guérin-Méneville (1832), is incorrect, the first author to describe this species was actually Latreille (in Milbert 1812) (see Cleva et al. 2007: 246, fig. 14C; Ng et al. 2008: 37).

Other genus included. Hirsutodynomene McLay, 1999 (type species by original designation: Dynomene spinosa Rathbun, 1917 ).

Diagnosis. Carapace wider or much wider than long, broadly rounded in outline, with “xanthoid” facies; dorsal surface moderately convex, may be areolate, smooth or granulate, may be laterally spiny, sparsely covered with short or long setae. Cervical groove as broad V, usually pronounced, never reaching, thus not forming notch with lateral carapace margin, interrupted between elongated gastric pits, or not interrupted; branchial groove faint, generally indistinct laterally or, rarely, joining lateral border of carapace; branchiocardiac variously marked. Anterolateral margin beginning slightly below infraorbital border, well defined, armed with distinct teeth, rarely by granules only. Posterior margin concave. Frontal margin broadly triangular, continuous above orbit; supraorbital margin gently oblique, may be notched, usually ornamented; infraorbital margin usually irregular, may be toothed, granular, notched. Orbits well defined, directed more or less obliquely; eyestalks rather short. Antenna with narrow urinal article beaked medially; second article with exopod firmly fixed. Proepistome very narrow. Anterior border of endostome not prominently raised. Mxp3 not firmly operculiform; basis separated from ischium by incomplete suture. Branchiostegite decalcified. Thoracic sternum slightly tilted posteriorly, wide, not entirely covered laterally by abdomen at level of P2–P3 coxae, a small portion of episternites 5, 6 remaining exposed when male abdomen folded. Sternites 1, 2 fused as pentagonal shield, variously pointed at anterior end; sternite 3 represented by narrow band at base of shield, delimited posteriorly by change in level ( Figure 3 C, 4A); suture 4/5 indistinct but limit between sternites 4, 5 marked transversely by setiferous, convex, line, may be salient, ornamented; sternites 4–8 mostly fused into single wide plate. Sterno-coxal depressions deep. Female sutures 7/8 ending well apart, inserted in ridged groove along internal border of sterno-coxal depression for P3; spermathecal aperture slightly posterior to coxal female gonopore, tiny, below prominence. Sterno-abdominal depression wide, shallow. Male abdomen with all somites free, wide, not entirely filling sterno-abdominal depression, leaving exposed thoracic sternites 1–3, mostly ( Figure 3 C) or totally ( Figure 3 D) sternite 4, and episternites 5, 6; first abdominal somite dorsally visible, narrow, slightly wider than somite 2. Somites 3–5 of males with vestigial, rudimentary pleopods, biramous, rarely uniramous. Pl1 vestigial in females. Uropods sexually dimorphic, immobile, rather large, occupying variable length of abdominal somite 6, not filling whole length of somite 6 in males and females ( Figure 5 A, C–H) in contrast to females in some species ( Figure 5 B). Abdominal holding structure sternal (but only restricting lateral movements of abdomen); in males a small tubercle on episternite 5 facing either uropod margin or abdomen margin (location dependent on size of uropod and its extension along somite 6); tubercle lost in mature females. Chelipeds equal, either stout or slender; fingers largely gaping at base, dactylus strongly curved. P2–P4 conspicuously ornamented with spines or granules; dactyli with 4–6 spines on inferior margin. P5 sexually dimorphic, reduced; basis and ischium free, not fused to merus; dactylus rudimentary, with obsolete subchelate mechanism. Coxa of P5 modified in males, extended to enclose penis. Gonopod 1 stout, forming half-rolled tube, with apical plate. G2 needle-like, with varying number of subterminal spines.

Remarks. The subfamily comprises only two genera: Dynomene , with McLay (2001b) recently describing two new species from Guam, and Hirsutodynomene , with McLay & Ng (2005) adding one new species from the Philippines ( Table 1).

Figures

FIGURE 1. Representative species of the four subfamilies of Dynomenidae, overall view. A, Acanthodromiinae n. subfam.: Acanthodromia margarita (Alcock, 1899), Balicasag Island, Panglao, Bohol, Visayas, Philippines (ZRC) (see McLay & Ng 2005: 18); B, Paradynomeninae n. subfam.: Paradynomene tuberculata Sakai, 1963, Balicasag Island, Panglao, Bohol, Visayas, Philippines (ZRC) (see McLay & Ng 2004: 4); C, Metadynomeninae n. subfam.: Metadynomene tanensis (Yokoya, 1933) with its undulating tomentum, Balicasag Island, Panglao, Bohol, Visayas, Philippines (ZRC) (see McLay & Ng 2005: 25); D, Dynomeninae Ortmann, 1892: Hirsutodynomene vespertilio McLay & Ng, 2005, Balicasag Island, Panglao, Bohol, Visayas, Philippines (ZRC) (see McLay & Ng 2005: 21). E, Paradynomene tuberculata Sakai, 1963, New Caledonia, frontal view showing the characteristic “ face ” (ZRC). (All photographs courtesy of P. K. L. Ng).

FIGURE 3. Metadynomeninae n. subfam. (A, B) and Dynomeninae Ortmann (C, D), views of thoracic sternum and abdomen (A, C, D) and ventral surface of abdomen (B). A, Metadynomene tanensis (Yokoya, 1933), male 12, 5 x 13, 5 mm, New Caledonia, SMIB 2 (MNHN-B 25583): abdominal holding by P 2 coxa; B, Metadynomene crosnieri McLay, 1999, holotype, male, 23.2 x 22.7 mm, western Indian Ocean, îles Glorieuses, Benthedi Exp. (MNHN-B 22510): biramous vestigial pleopods 3 – 5; detail at right; C, Dynomene hispida (Latreille, in Milbert 1812), male 6.9 x 8.8 mm, New Caledonia (MNHN-B 22091): abdominal holding mechanism by sternal structure; D, Hirsutodynomene spinosa (Rathbun, 1911), male, 14.3 x 16.4 mm, western Indian Ocean, îles Glorieuses (MNHN-B 6899): abdominal holding mechanism by sternal structure (see Bouchard 2000: fig. 24 A). a 3 – a 6, abdominal somites 3 – 6; cx 1 – cx 4, coxae of P 1 – P 4; e 4 – e 6, episternites 4 – 6; pl 3 – pl 5, vestigial pleopods on abdominal somites 3 – 5; pr, coxal projection; s, shield; t, telson; u, uropod; 4, sternite 4. Scale bars: 1 mm.

FIGURE 5. Uropods in the four dynomenid subfamilies (dorsal surface, unless mentioned otherwise). A – H, Dynomeninae Ortmann, 1892; I – L, Metadynomeninae n. subfam.; M – N, Paradynomeninae n. subfam.; O – P, Acanthodromiinae n. subfam. A – B, Dynomene hispida (Latreille, in Milbert 1812): A, male, New Caledonia (MNHN-B 22091); B, female (After McLay 1999: fig. 18 g). C, Dynomene pilumnoides Alcock, 1900, female (After McLay 1999: fig. 21 g). D, Dynomene praedator A. Milne-Edwards, 1879, male (After McLay 1999: fig. 19 g). E, Dynomene pugnatrix De Man, 1889, male (After McLay 1999: fig. 22 g). F, Dynomene filholi Bouvier, 1894, male (After McLay 1999: fig. 20 g). G, Hirsutodynomene spinosa (Rathbun, 1911), male (After McLay 1999: fig. 23 g). H, Hirsutodynomene ursula (Stimpson, 1860), female (After McLay 1999: fig. 24 g). I – J, Metadynomene tanensis (Yokoya, 1933): I, male, New Caledonia, dorsal surface (MNHN-B 25583); J, female, ventral surface (After McLay 1999: fig. 27 g). K – L, Metadynomene crosnieri McLay, 1999, male, holotype, western Indian Ocean, îles Glorieuses (MNHN-B 22510): dorsal (K) and ventral (L) surfaces; M – N, Paradynomene sp., New Caledonia (MNHN-B 24779); M, male: ventral surface; N, female: dorsal surface (After McLay 1999: fig. 32 g). O, Acanthodromia erinacea A. Milne-Edwards, 1880, female, Puerto Rico (USNM 124263); P, Acanthodromia margarita (Alcock, 1899), female (After McLay 1999: fig. 31 f).