Calliaxina, Ngoc-Ho, 2003

Ngoc-Ho, Nguyen, 2003, European and Mediterranean Thalassinidea (Crustacea, Decapoda), Zoosystema 25 (3), pp. 439-555 : 493-494

Genus Calliaxina n. gen.

Calliax – de Saint Laurent & Manning 1982: 211.

TYPE SPECIES. — Calliax punica de Saint Laurent & Manning, 1982 , by present designation.

SPECIES INCLUDED. — Calliaxina novaebritanniae (Borradaile, 1899) n. comb., Calliaxina sakaii (de Saint Laurent, 1979) n. comb.

ETYMOLOGY. — The species name refers to its relationship with Calliax . The gender is feminine.

DIAGNOSIS. — Carapace lacking dorsal oval, with transverse suture posterior to cervical groove. Rostrum broadly triangular with pointed tip or small rostral spine, pointed lateral projection on either side. Second abdominal segment largest, slightly larger than sixth, lateral tufts of setae present on segments 3-5. Telson approximately 1.2-1.6 times as wide as long, lateroposterior angles rounded, posterior border straight or slightly concave in median part.

Eyestalk weakly flattened dorsoventrally; cornea diskshaped. A1 peduncle shorter than that of A2. Mxp1 endopod elongate, epipod large, tapering distally. Mxp2 with bilobed epipod and single arthrobranch. Mxp3 operculiform, propodus with lower border strongly expanded proximally, dactylus rounded, exopod present.

P1 equal and similar; P3 with heel on proximal lower border. P4 propodus linear. P5 subchelate.

Single arthrobranch on Mxp2, paired arthrobranch on Mxp3 and P1-4.

Male Plp1 uniramous with appendix interna. Male Plp2 biramous with appendix interna and appendix masculina. Female Plp1 uniramous, female Plp2 biramous with finger-like appendix interna. Plp3-5 biramous, foliaceous, appendix interna finger-like, sitting side by side with mesial border of endopod. Uropodal endopod overreaching telson by about half its length; dorsal plate on exopod with distal setal row well apart from rounded posterior border.

REMARKS

Differences between the genera Calliax , Calliaxina n. gen. and Paraglypturus , based on their type species Calliax lobata , Calliaxina punica n. comb. and Paraglypturus calderus Türkay & Sakai, 1995 are presented in Table 1.

De Saint Laurent & Manning (1982) stated that Calliax lobata and Calliaxina punica n. comb., both from the Mediterranean, were significantly different. They actually differ, as listed above, by many characters, the most important of which concern the morphology of the Mxp3, the P1, and also the male and female Plp1, Plp2.

Calliaxina n. gen. and Paraglypturus ( Fig. 20 K- O) (see also Türkay & Sakai 1995: figs 2-6) are similar in having an exopod on the Mxp3 but the ischium-merus shape differs (operculiform in Calliaxina n. gen., Fig. 19K , subpediform in Paraglypturus , Fig. 20K ). Other discrepancies are: 1) the pointed rostrum and anterolateral projections are present in Calliaxina n. gen. ( Fig. 19A, E ) (absent in Paraglypturus ); 2) Mxp2 is with arthrobranch in Calliaxina n. gen. (without in Paraglypturus ); 3) P1 are subequal, similar, laterally compressed in Calliaxina n. gen. ( Fig. 19C ) (unequal, dissimilar, not compressed in Paraglypturus ); 4) male Plp1 bears an appendix interna in Calliaxina n. gen. ( Fig. 20C ) (not in Paraglypturus , Fig. 20M ); 5) the appendix interna on Plp3-5 is digitiform in Calliaxina n. gen. ( Fig. 20G ) (stubby in Paraglypturus , Fig. 20Q ); and 6) the uropodal endopod overreaches the telson for at most half of its length in Calliaxina n. gen. ( Fig. 19D ) (it is much longer in Paraglypturus ).

Paraglypturus calderus material was taken from hydrothermally influenced sediments of the Mariana Arc. This is an environment of hot water (porewater temperature of over 50°C) and shallow depth (64-114 m) ( Türkay & Sakai 1995). Besides characters shown above in comparison with Calliaxina n. gen., this species displays a few others of unknown significance ( Türkay & Sakai 1995: figs 3, 6): 1) eyestalks are weakly flattened dorsoventrally with prominent, globulous, subterminal, well pigmented corneas; 2) the uropodal endopod in large males and females bears a yellow transparent circular structure on lower plate; and 3) eggs are small (0.2 mm in diameter) and attached to the Plp1 only in most females (seven/ eight females), larger (0.5 mm in diameter) and attached to Plp 1- 5 in one female ( Türkay & Sakai 1995: 29). Eggs are also few (less than 10 per female in sample SMF 22949 including three females).

Considering the morphological dissimilarities alone, differentiation between Calliaxina n. gen. and Paraglypturus seems justified. Paraglypturus calderus , nevertheless, shares with members of Callianassidae , and the Eucalliacinae in particular, many characteristics: 1) absence of a dorsal oval on the carapace; shape of eyestalks; 2) A1 peduncle shorter than that of A2; 3) Mxp3 propodus and dactylus ovate; 4) appendix masculina present on male Plp2; and 5) a dorsal plate present on the uropodal exopod. Its remote position in Tudge et al. ’s (2000) cladogram as the sister taxon of all other callianassids is enigmatic.

Callianassa tooradin Poore & Griffin, 1979 was placed in Paraglypturus by Sakai (1999a). It shares similarities (see Poore & Griffin 1979: fig. 36) with Paraglypturus calderus in: 1) absence of a pointed rostrum and anterolateral projections on the carapace; 2) subpediform Mxp3 with exopod; 3) P1 unequal; 4) appendix interna absent from male Plp1; and 5) uropods much longer than the telson. There are differences: 1) small eye corneas instead of large, globulous; 2) minute Mxp1 endopod instead of elongate; 3) arthrobranch present on Mxp2; and 4) appendix masculina absent from male Plp2. Nevertheless, the similarities listed above, the morphology of Mxp3 especially, link the two species. It is proposed here that Paraglypturus tooradin ( Poore & Griffin, 1979) provisionally remains in that genus as suggested by Sakai pending additional material for study in future.

Figures

FIG. 20. — A-I, Calliaxina punica (de Saint Laurent & Manning, 1982) n. comb.; A-G, from Le Brusc, France (MNHN Th 1402); A, B, maxillule and maxilla; C, D, maxilliped 1 and 2; E, F, female pleopod 1 and 2; G, pleopod 3; H, I, from Mediterranean? (MNHN Th 1355), male pleopod 1 and 2; J, Calliaxina sakaii (de Saint Laurent, 1979) n. comb., holotype, from Tomioka,Japan (MNHN Th 312), male pleopod 1; K-Q, Paraglypturus calderus Türkay & Sakai,1995,paratype, from Marianas (SMF 22950); K, L, maxilliped 3 and 2; M, N, male pleopod 1 and 2; O, P, female pleopod 1 and 2; Q, pleopod 3. Scale bars: A, B, L-P, 0.5 mm; C-K, Q, 1 mm.

FIG. 19. — Calliaxina punica (de Saint Laurent & Manning, 1982) n. comb.; A, paratype, from Gulf of Tunis, Tunisia, carapace, dorsal view (from de Saint Laurent & Manning 1982); B-L, from Le Brusc, France (MNHN Th 1402); B, lateral view, pereopod 1 and 5 omitted; C, pereopod 1; D, telson and uropods; E, anterior part of carapace; F-I, pereopod 2-4 and distal part of pereopod 5; J, K, maxilliped 3 and mesial view of ischium, merus, carpus; L, mandible. Scale bars: A, C-K, 1 mm; B, 2 mm; L, 0.5 mm.