Rayllianassa Komai and Tachikawa, 2008

Poore, Gary C. B., Dworschak, Peter C., Robles, Rafael, Mantelatto, Fernando L. & Felder, Darryl L., 2019, A new classification of Callianassidae and related families (Crustacea: Decapoda: Axiidea) derived from a molecular phylogeny with morphological support, Memoirs of Museum Victoria (Mem. Mus. Vic.) 78, pp. 73-146 : 98

Rayllianassa Komai and Tachikawa, 2008

Rayllianassa Komai and Tachikawa, 2008: 42–43 .—Komai and Fujita, 2014: 551–552.

Notiax .— Sakai, 2011: 381 (partim).

Type species. Callianassa amboinensis De Man, 1888 , by original designation and monotypy.

Diagnosis. Hermaphrodite. Rostrum obsolete or obtusely triangular, flat, not reaching cornea. Pleomere 1 tergite undivided or with weak transverse step. Eyestalk distal lobes obliquely truncated, apices diverging. Antennular peduncle exceeding antennal peduncle by about half length of article 3; articles 2 and 3 with single lateral row of 6–10 well-spaced long setae along lower margin. Antennal scaphocerite simple, longer than wide, acute. Mandibular molar calcified, swollen projection without sharp edge, incisor with few teeth. Maxilliped 3 merus wider at ischium-merus suture than long. Male major cheliped merus without prominent hook or spine on lower margin; carpus and propodus ovoid in cross-section, upper and lower margins not markedly carinate; propodus distal margin with small lateral tooth. Minor cheliped about two-thirds width of major cheliped, both swollen; carpus upper margin as long as or shorter than propodus. Pereopod 3 propodus rectangular, lower margin deeply convex, leading to broadly rounded free proximal lobe. Uropodal endopod ovoid, usually longer than wide, anterior margin straight or slightly convex, posterodistal margin evenly convex, with facial spiniform setae on rib. Uropodal exopod posterodistal margin with row of 6–8 long blade-like setae proximal to long setae on distal margin. Telson lateral margins convex; anterolateral lobe obsolete, undefined; slightly concave, sometimes with medial spine.

Remarks. Rayllianassa amboinensis is recognisable by the absence of a hook on the merus of the major cheliped, the propodi being swollen and the pair being little different in size. The lobes on the eyestalks are truncate-oblique and the maxilliped 3 particularly broad. Komai et al. (2014a) added a second species R. rudisulcus and emended the generic diagnosis to accommodate the presence or absence of a dorsal oval, but the authors were ambivalent about the value of this character in callianassid systematics. This species and another were shown by Robles et al. (in press) to differ on both molecular and morphological criteria (see Rudisullianassa below where the two genera are compared).

Rayllianassa amboinensis has been reported from throughout the Indo-West Pacific and illustrated several times since its discovery in Ambon, Indonesia ( Komai et al., 2014a; Komai and Tachikawa, 2008; Ngoc-Ho, 2005; Poore and Griffin, 1979; Sakai, 1984, 1988, 1999a). There is considerable discrepancy between the illustrations. Robles et al. (in press) found substantial genetic difference between eight individuals from Papua New Guinea, Philippines and the Line Islands pointing to the probability of more than one species in this genus.

All authors cited above have reported only females with the exception of Sakai (1999a) who reported two males and a female from Ambon, all twice as long as the “female” holotype and other subsequent records. Examination of all the material available to us shows them to be hermaphrodites with both male and female gonopores. Ngoc-Ho(1991) illustrated minute pleopods 1 and 2 on a single male that was renamed Callianassa ngochoae bySakai (1999a) and later synonymised by Komai et al. (2014a). The generic position of Callianassa ngochoae is uncertain. Males of species of Rudisullianassa and Spinicallianassa have also never been reported. All “females” with typical pleopods 1 and 2, including ovigerous individuals, have both female gonopores on coxae of pereopods 3 and male gonopores on coxae of pereopods 5 and are probable hermaphrodites.