Aphanodactylus Tesch, 1918

Ahyong, Shane T. & Ng, Peter K. L., 2009, Aphanodactylidae, a new family of thoracotreme crabs (Crustacea: Brachyura) symbiotic with polychaete worms, Zootaxa 2289, pp. 33-47 : 36-38

Aphanodactylus Tesch, 1918

Aphanodactylus Tesch, 1918: 283 [type species: A. sibogae Tesch, 1918 , by monotypy].

Diagnosis. Carapace wide, ovate, males 1.4–1.5 times wider than long, females 1.6–1.9 times wider than long; lateral margins cristate or subcristate, but not continuous to external orbital end; surface smooth, glabrous, with few scattered pits. Front narrow, deflexed broadly triangular in frontal view; straight to weakly sinuous in dorsal view. Orbit transverse; margins entire, unarmed; infraorbital margin mesially terminating in acute angle; supraorbital margin demarcated from antennular fossa by even curve; infraorbital and supraorbital margins not extending laterally beyond cornea or continuing laterally beyond orbit proper. Eyes short, mobile, fully occupying orbit. Antennules articulating transversely to slightly obliquely. Epistome short, medially sunken. Maxilliped 3 ischium longer than merus, both subquadrate. Thoracic sternites 1 and 2 completely fused, broadly angular anteriorly; sternites 2/3 demarcated by shallow groove; sternites 3/4 fused, laterally unarmed; sternites 4–8 demarcated by narrow grooves, those demarcating sternites 4–7 incomplete medially; without longitudinal groove. Cheliped merus and carpus unarmed, with sparse plumose setae. P2–5 similar in shape, P3 longest; meri about twice as long as high, as long as or slightly longer than respective carpi and propodi combined; with plumose setae on flexor and extensor margins; meri with or without teeth along flexor margin. P4 markedly shorter than preceding leg, dorsal to others. P2–5 with short spines on distoflexor angle of propodi opposing dactyli; dactyli very short, claw-like. Male abdomen simple, triangular; telson and all somites free; widest at somite 1; thoracic sternite 8 exposed when abdomen closed. Female abdomen with telson and all somites freely articulating, widest at somite 4. Vulva ovate, maximum width not exceeding half width of sternite 6. G1 simple, slender, broadly curved. G2 small, about 1/3 length of G1, slender, apex blunt.

Included species. Aphanodactylus edmondsoni Rathbun, 1932 , A. sibogae Tesch, 1918 , A. loimiae Konishi & Noda, 1999 , A. panglao Ng & Naruse, 2009 .

Material examined. Aphanodactylus edmondsoni Rathbun, 1932 : BPBM 3576, holotype female (cl. 9.5 mm, cw. 16.1 mm), Oahu, Hawaiian Is., coll. C. H. Edmondson, 27 November 1931; BPBM 3577, 1 male (cl. 8.0 mm, cw. 11.6 mm), Oahu, Waimanalo, Hawaii, coll. C. H. Edmondson, 27 November 1931; ZRC 2000.0542, 1 male (cl. 8.2 mm, cw. 11.5 mm), 1 female (cl. 10.2 mm, cw. 16.9 mm), Oahu, Hawaiian Is., 1930s, coll. C. H. Edmondson. — Aphanodactylus loimiae Konishi & Noda, 1999 : CBM 5341, 1 male (cl. 7.4 mm, cw. 10.3 mm), 1 ovigerous female (cl. 8.6 mm, cw. 13.9 mm), Kyan, Kuroshima I., Yaeyama Is., Ryukyus, 10 m deep, coral reef, in tube of Loimia ingens (Terebellidae) , 10 October 1999, coll. K. Nomura on SCUBA; CBM 5443, 1 ovigerous female (cl. 9.1 mm, cw. 15.3 mm), Ahra Beach, Kume-jima I., Okinawa Is., Ryukyus, 10 m deep, coral reef, inhabiting tube of Loimia ingens , 15 June 1995, coll. K. Nomura on SCUBA. — Aphanodactylus panglao Ng & Naruse, 2009 : NMCR, holotype ovigerous female (cl. 5.0 mm, cw. 8.8 mm) Napaling, Panglao I., Bohol Sea, Philippines, stn. B8, 3 m deep, 9°37.1′ N, 123°46.1′ E, by subtidal brushing of coral rock and debris, 7 June 2004, coll. Panglao Marine Biodiversity Project; ZRC, paratype male (cl. 3.1 mm, cw. 4.2 mm) ( ZRC), Panglao I., Bohol Sea, Philippines, associated with an unidentified terebellid worm, early 2000s, coll. J. Hinterkircher. — Aphanodactylus sibogae Tesch, 1918 : RMNH 2162, syntype female (cl. 5.4 mm, cw. 8.8 mm), east of Dangar Besar, Sapeh Bay, north coast of Sumbawa, Lesser Sunda Is., Indonesia, up to 36 m depth, SIBOGA Expedition st. 313, 14–16 February 1900; ZRC, 1 male (cl. 5.3 mm, cw. 7.8 mm), Sekotong, West Lombok, Indonesia, 16 May 2007, coll. D. L. Rahayu.

Remarks. Aphanodactylus is the best known and largest genus of the aphanodactylids, and appears to be closest to Gandoa (see Remarks under the account of Gandoa ). Four described species are presently known, all from the western Pacific and associated with terebellid polychaete worms. The taxonomy of these Aphanodactylus species has been treated and discussed in detail by Konishi & Noda (1999), Ng & Naruse (2009) and Ng et al. (in press). A male and female of A. loimiae are illustrated here to represent the genus ( Figs. 1 , 2 ).

Figures

FIGURE 1. Aphanodactylus loimiae, male, cl. 7.4 mm, cw. 10.3 mm (CBM 5341). A, habitus. B, cephalothorax, anterior view. C, right maxilliped 3. D, right chela. E, right P 5. F, thoracic sternum. G, left thoracic sternites 7 – 8, coxae, and genital papilla. H – I, left G 1, abdominal and thoracic sternal views, respectively. J – L, left G 2, mesial, sternal and abdominal views, respectively. M, abdomen. Scales: A, D, F, M = 3.0 mm; B, C, E, G = 1.5 mm; H, I = 1.0 mm; J – L = 0.5 mm.

FIGURE 2. Aphanodactylus loimiae, ovigerous female, cl. 8.6 mm, cw. 13.9 mm (CBM 5341). A, habitus. B, cephalothorax, anterior view. C, thoracic sternum. D, right chela. E, right P 4. Scales A, C, D = 3.0 mm; B, E = 1.5 mm.