Gopkittisak, Naruse, Tohru & Clark, Paul F., 2009

Naruse, Tohru & Clark, Paul F., 2009, Establishment of a new genus for Asthenognathus gallardoi Serène & Soh, 1976 within Gaeticinae Davie & N. K. Ng, 2007 (Crustacea: Decapoda: Brachyura: Varunidae), Zootaxa 1987, pp. 61-68 : 62-63

Gopkittisak n. gen.

Asthenognathus — Serène & Soh, 1976: 27 (part); Jiang et al., 2007: 77 (part).

Type species: Asthenognathus gallardoi Serène & Soh, 1976 , by present designation.

Diagnosis. Carapace elliptical, dorsal surface with transverse ridges; posterior lateral facet present. Short infraorbital margin extended downwards from external orbital angle, ventral side of orbit demarcated by suborbital crista, continuous laterally as far as below lateral end of anterior lateral epibranchial crista of dorsal surface. Epistome short. Eyes well-developed. Antennule basal article large. Antennal basal article reaching lateral frontal angle, inner orbital tooth reaching middle to lateral frontal angle. Third maxillipeds less than two-thirds of buccal cavern when closed; ischium and merus subrectangular, these segments divided by oblique border; carpus attached to lateral half of distal margin of merus, propodus and dactylus attached to distal end of respective proximal segment; dactylus with long setae, reaching concavity of thoracic sternites 1–3. Male thoracic stenites 1/2 fused, stenite 3 demarcated from stenites 1/2 and 4, female thoracic stenites 1/ 2 and 3/4 fused respectively, both male and female thoracic stenites medially concave. Male third to sixth abdominal segments functionally fused.

Etymology. The genus is named in memory of Mrs Pharadee (Gop) Uchuphab and Mr Kittisak Raksasri who perished when the Tsunami swept through the Ranong Coastal Research Station, Ranong Province, Thailand on 26 December 2004. They are both missed, but still remembered. The name is an arbitrary combination of two first names and the gender is neuter.

Remarks. Peter K.L. Ng et al. (2008) stated that Asthenognathus gallardoi Serène & Soh, 1976 should not be assigned to Asthenognathus , as it is markedly different from the type species ( A. inaequipes ) in the transversely more elongated elliptical shape of the carapace and the presence of the transverse ridges on the carapace ( Fig. 1 a, b; Serène & Soh, 1976: Fig. 28B, Pl. VIII A; Ghani & Tirmizi, 1991: Fig. 1 A, B; Jiang et al., 2007: Fig. 1 a). These morphological differences warrant that A. gallardoi should be placed in its own genus. Gopkittisak , new genus, is here established to accommodate A. gallardoi .

Systematic position of G. gallardoi is also problematic. Davie & N.K. Ng (2007) recently established the subfamily Gaeticinae for Gaetice Gistel, 1848 and Sestrostoma Davie & N.K. Ng, 2007 . The diagnostic characters of this subfamily are: 1) long setae for suspension feeding on the palp of the third maxilliped, 2) a longitudinal sulcus on the anterior segments of the sternum for the long setae of the palp of third maxilliped, and 3) fused third to sixth male abdominal segments. Among these characters, G. gallardoi share the long setae of the palp of the third maxilliped and the fused male abdominal segments ( Fig. 2 a; Serène & Soh, 1976: Fig. 28A; Ghani & Tirmizi, 1991: Fig. 1 C, F; Jiang et al., 2007: Fig. 1 d, e). Although G. gallardoi lacks the longitudinal sulcus on the anterior segments of the sternum, the anterior part of the sternum is gently concave so that the long setae can be accommodated. Furthermore, Gaetice and Gopkittisak share a markedly oblique border of the merus and ischium of the third maxilliped. The presence of these similar characters indicates that it is best to place Gopkittisak within Gaeticinae .

Paracleistostoma fossulum Barnard, 1955 , also possesses the transverse ridges on the dorsal surface of the carapace (P.K.L. Ng et al., 2008: 229). The systematic position of P. fossulum is uncertain, however. Barnard (1955) placed it under Ocypodidae , but Manning & Holthuis (1981: 209) stated that" [ P. fossulum is] certainly no Paracleistostoma and possibly not even an ocypodid". Peter K.L. Ng et al. (2008) argued that the chela and the third maxilliped of P. fossulum is unlikely that of any Camptandriidae , and they transferred it to the Varunidae , although they treated it as "Subfamily incertae sedis". Gopkittisak gallardoi is similar to P. fossulum in the presence of the dorsal ridges, but G. gallardoi can be differentiated from P. fossulum by the characters listed in Table 1.

Monod (1933) described Asthenogathus atlanticus from Atlantic side of Morocco. The holotype of A. atlanticus possesses Gopkittisak - type of the third maxilliped, with oblique border between merus and ischium and long setae from dactylus ( Monod, 1933: Fig. 8A, B). He described the male abdomen as 7-segmented, but it is not certain whether it is functionally fused or completely segmented. Further study may prove that A. atlanticus is indeed a member of Gaeticinae . In that case, a new genus is needed to accommodate A. atlanticus as it is different from other gaeticine genera. The taxonomic statuses of the specimens subsequently recorded as “ A. atlanticus ” are also unclear. Monod (1956) reported 6 specimens of A. atlanticus from West Africa (2 ♂ and 2 Ƥfrom Mauritania; 1 ♂ from Senegal; 1 Ƥ from the Gold Coast). Although at least the female specimen from the Gold Coast have a similar third maxilliped with the holotype of A. atlanticus ( Monod, 1956: Fig. 543), the specimen from Senegal possesses a horizontal border between merus and ischium of third maxilluped ( Monod, 1956: Fig. 544), which is same condition with Asthenognathus sensu stricto. The Senegal specimens are more similar to A. inaequipes than to A. hexagonum in its shape of the carapace, but the ischium of the third maxilliped is shorter than that of A. inaequipes , suggesting that it is most probably an undescribed species. Moreover, Bocquet (1963: Fig. 1 ) recorded A. atlanticus from France, but it appears to be a different new species as it has relatively wider carapace and ambulatory meri ( Bocquet, 1963: 74, Fig. 7). Asthenognathus atlanticus has also been recorded from various authors (see Schmitt et al., 1973; Fransen, 1991; d'Udekem d'Acoz, 1999). A taxonomic revision is necessary for the Atlantic Asthenognathus -like species.

TABLE 1. Characters distinguishing Gopkittisak gallardoi from Paracleistostoma fossulum Barnard, 1955 .

Figures

FIGURE 1. Gopkittisak gallardoi (Serène & Soh, 1976), Ƥ (8.0 × 3.9 mm), NHM 2008.998: a, dorsal view of carapace; b, anterior view of cephalothorax; c, third maxilliped; d, left chela; e, dorsal view of right cheliped. Scale bars = 1 mm.

FIGURE 2. Gopkittisak gallardoi (Serène & Soh, 1976). a, 3 abdomen and telson; b, 3 thoracic sternites 7 & 8 (left); c, left G 1, ventral view; d, left G 1, inner view; e, left G 2, ventral view; f, Ƥ abdomen and telson. a, 3 (6.2 × 3.4 mm), NHM 2008.4621 – 4622; b – e, 3 (7.4 × 4.0 mm), ZRC 2008.1053; f, Ƥ (8.0 × 3.9 mm), NHM 2008.998. Scale bars = 1 mm.