Re-appraisal of the families and subfamilies of Trapezioidea Miers, 1886, with establishment of a new family, Ectaesthesiidae (Crustacea: Decapoda: Brachyura) Author Ng, Peter K. L. Author Ahyong, Shane T. Author Castro, Peter text Raffles Bulletin of Zoology 2023 2023-10-30 71 606 631 journal article 10.26107/RBZ-2023-0047 2345-7600 10271307 821BC4EC-5AF9-4727-84A3-C44839DFBE28 Family Calocarcinidae Števčić, 2005 , new status Calocarcinini Števčić, 2005: 40 . Philippicarcinini Števčić, 2011: 131 . Diagnosis. Carapace hexagonal; antero- and posterolateral margins clearly demarcated, anterolateral margin with 1 or 2 teeth; front weakly bilobed, almost smooth; posterolateral margin gently convex to sinuous ( Fig. 11E ); carapace relatively low to high, dorsal surface gently or distinctly convex in frontal view ( Fig. 11E–H ); posterior margin of epistome with median lobe small, lateral margin relatively short, with 2 triangular lobes, separated by V-shaped cleft from pterygostomial lobe ( Fig. 5D ). Basal antennal article quadrate, mobile, peduncle excluded from orbit. Maxilliped 3 merus quadrate, wider than long, anteroexternal part not auriculiform, as wide as rectangular ischium (at midlength); distal edge of exopod reaching to distal edge of merus ( Fig. 5E ). Chelipeds long, heterochelous, larger cheliped about twice carapace width; merus quadrate in dorsal view, flexor and extensor margins smooth; carpus inner angle with or without short spine, propodus outer surface smooth, without tubercles ( Fig. 11E ). P2–5 short, longest pereopod slightly longer than carapace width; merus relatively stout; merus, carpus and propodus smooth, unarmed ( Fig. 11E ); dactylus flexor margin with robust setae; without transverse, comb-like rows of setae. Sternopleonal cavity reaching anteriorly to level of midlength of P2 coxae ( Fig. 7F, G ); tubercle of male pleonal-locking mechanism distinct, on posterior one-third of thoracic sternite 5, may be near suture with sternite 6 ( Fig. 8K ). Male pleon subquadrate; linguiform, lateral margins of somites 3–6 subparallel, somites 3–5 fused with sutures visible medially ( Figs. 7F, G , 8E ). G1 strongly sinuous or curved, relatively slender to stout, distal margins lined with short or long spinules ( Fig. 9K, M ). G2 relatively slender, three-quarters to subequal to length of G1, distal portion elongated, filiform ( Fig. 9L, N ). Vulva relatively large, ovate to triangular, positioned on anterior half of sternite 6, adjacent to suture with sternite 5, vulvae positioned close to median line, directed inwards; large lateral, flexible sternal vulvar cover ( Fig. 10F, G ). Fig. 10. Vulvae. A, Tetralia nigrolineata (9.8 × 8.6 mm) (ZRC 2019.0701), Japan; B, Tetraloides heterodactylus (8.3 × 6.7 mm) (ZRC 2019.0699), Japan; C, Trapezia cymodoce (12.2 × 10.1 mm) (ZRC 2007.0079), Singapore; D, Quadrella maculosa (5.9 × 5.0 mm) (ZRC 2003.0352), Sulawesi, Indonesia; E, Sphenomerides trapezioides (7.5 × 5.7 mm) (ZRC 2000.2103), Madagascar; F, Calocarcinus africanus (12.0 × 10.1 mm) (ZRC 2008.1281), New Caledonia; G, Philippicarcinus oviformis (14.5 × 10.0 mm) (ZRC 2009.0058), Philippines; H, Domecia acanthophora (7.4 × 5.4 mm) (ZRC 2000.1551), Caribbean Sea, Panama; I, Cherusius triunguiculatus (6.4 × 4.6 mm) (ZRC 2016.0121), Easter Island; J, Palmyria palmyrensis (4.9 × 3.4 mm) (UF 12897), Réunion. Genera included. Calocarcinus Calman, 1909 , and Philippicarcinus Garth & Kim, 1983 . Remarks. In their discussion of the higher classification of trapezioids, Lai et al. (2009: 407) opined that the “phylogenetic position of Calocarcinines raises additional issues”. They noted that while the Calocarcininae is a stable monophyletic clade, the support for its affinity to Trapeziinae and Quadrellinae is not high in MP analyses (though well supported in BI, PP = 1.0). This lends some support to Schweitzer (2005) , who suggested that Calocarcininae might not belong in Trapeziidae . A similar hypothesis was proposed by Clark & Guerao (2008) , who commented that calocarcinine larvae are very different from those of trapeziines. Although these hypotheses might be correct, an alternative possibility is that the more typically ‘xanthoid’ carapace of the calocarcinines, as well as their xanthoid or eriphioid-like larvae, merely reflects their plesiomorphic condition. The morphological reappraisal herein supports the suggestions of Lai et al. (2009) that Calocarcinus and Philippicarcinus should not be placed in Trapeziidae and should instead be treated as a separate family. As discussed earlier for Sphenomeridinae , these genera do not have comb-like rows of feeding setae on their P2–5 dactyli. Most significantly, their G2 is very long, sometimes subequal to the length of G1 ( Fig. 9L, N ). In all other trapeziids and tetraliids, G2 is at most half the length of G1 ( Fig. 9B, D, F, H, J ). In Domeciidae and Ectaesthesiidae , G2 is two-thirds to three-quarters the length of G1, but their G1 forms are completely different ( Figs. 9O–R ). As noted above, Števčić (2005) recognised a separate trapeziid tribe, Philippicarcinini Števčić, 2005 , for Philippicarcinus . Calocarcinus and Philippicarcinus are so similar that there is no need to separate them into two subfamilies. As a result, on the morphological evidence available, Philippicarcinini is a junior synonym of Calocarcinidae . Castro (1997b: 62) indicated that Calocarcinus crosnieri Galil & Clark, 1990 was probably a junior synonym of C. africanus , Calman, 1909 as there were no major differences observed between the two taxa other than the proportionally longer adult cheliped and proportionately shorter and stouter G1. They are here regarded as subjective synonyms. Calocarcinids seem to utilise a variety of hosts, from azooxanthellate (ahermatypic)scleractinian corals, antipatharians, alcyonaceans, gorgonians, to sponges ( Castro, 2015 ).