Gandoa Kammerer, 2006

Ng, Peter K. L. & Rahayu, Dwi Listyo, 2016, On the genera Selwynia Borradaile, 1903, and Gandoa Kammerer, 2006, with descriptions of two new species from Papua New Guinea and French Polynesia (Crustacea: Decapoda: Brachyura: Aphanodactylidae), Zootaxa 4092 (3), pp. 339-370 : 363-364

Gandoa Kammerer, 2006

Voeltzkowia Lenz, 1905: 364 [type species: Voeltzkowia zanzibarensis Lenz, 1905 , by monotypy]; Schmitt et al. 1973: 135 (in list); Ng et al. 2008: 247 (in list).

Gandoa Kammerer, 2006: 270 [replacement name of Voeltzkowia Lenz, 1905 , preoccupied by Voeltzkowia Boettger, 1893 (Reptilia) ]; Ng & Naruse 2009: 288; Ahyong & Ng 2009: 38; Ng & Clark 2014: 3; Castro 2015: 553 (in list).

Diagnosis. Carapace wide, ovate, females ca. 1.4 times wider than long; males unknown; lateral margins subcristate; surface with numerous prominent, relatively deep 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 gently curving low ridge; lateral part of orbit distinctly extended laterally to meet the anterolateral margin; inner part of supraorbital margin forms distinct groove which extends to protogastric region. Eyes short, mobile. Antennules folding slightly obliquely. Epistome short, medially sunken. Third maxilliped ischium subquadrate; merus rounded. Thoracic sternites 1, 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, carpus unarmed; outer surface of chela, notably at bases of fingers with dense pubescence. P2–P5 similar in shape, P3 longest, P5 shortest; merus about twice as long as high, as long as or slightly longer than respective carpi, propodi combined; with plumose setae on flexor, extensor margins; merus of P2–P4 usually unarmed or with 1 submedian tooth along flexor margin. P2–P5 without short spines on distoflexor angle of propodus opposing dactylus; dactylus very short, claw-like. Male abdomen simple, triangular; telson, all somites free; somite 1 widest; thoracic sternite 8 exposed when abdomen closed. Female abdomen with telson, all somites freely articulating, widest at somite 4. Vulva ovate, maximum width not exceeding half width of sternite 6. (Modified from Ahyong & Ng 2009: 38).

Remarks. Gandoa is superficially similar to Selwynia in carapace and ambulatory leg shape and structure; however, it can be immediately distinguished in having the lateral edges of the orbit extended laterally to meet the anterolateral margin ( Figs. 17 D, 18B, 19B, 20D) and the inner part of the supraorbital margin forms a distinct groove which extends to the protogastric region of the carapace ( Figs. 17 B, 18B, 19A, B, 20D). The merus of the third maxilliped of Gandoa ( Figs. 18 A, 20C) is distinctly more rounded than any Selwynia species. The dorsal surface of the carapace and surfaces of the chelipeds of Gandoa are distinctly punctate ( Figs. 19 A, B, 20A) distinguishing it from Selwynia . Although the dorsal surface of the carapace of Selwynia is also punctate, the depressions are relatively smaller and shallower. In addition, the outer surface of the chela of the female lectotype of G. brevipes and holotype female of Gandoa zanzibarensis have dense pubescence at the base of the fingers ( Figs. 17 D, E, 18C, 19D), which easily distinguishes it from Selwynia . The distoflexor angle of the propodus of P2–P5 opposing the dactylus is also unarmed in Gandoa ( Fig. 18 E, F, 20E–G) but almost always has short spines in Selwynia (e.g., Figs. 4 J, 7C–H, 12C, 16C, D).

Examining photographs of the preserved type specimen, Ng & Naruse (2009: 288–289) transferred Pinnixa brevipes H. Milne Edwards, 1853 , to Gandoa because its dorsal carapace surface was described as punctate (H. Milne Edwards, 1853: 220), and the carapace appeared to be more rectangular with the orbits more elongate. They also noted that the only aphanodactylid known from the Indian Ocean thus far was Gandoa . Ng & Clark (2014), who found that Selwynia laevis Borradaile, 1903 , from the Maldives was congeneric with Aphanodactylus sibogae Tesch, 1918 , from Indonesia, followed this classification but noted that there was now a second genus known from the Indian Ocean and the generic status of G. brevipes needs to be re-evaluated. The lectotype of Pinnixa brevipes is in poor condition ( Fig. 17 A, D), and although the carapace is soft, the key characters are still visible. We can now confirm the observations of Ng & Naruse (2009) that it is a member of Gandoa . Pinnixa brevipes clearly possesses the post supraorbital-protogastric groove present on the anterior part of the carapace and the orbit clearly has the lateral extension, diagnostic features for the genus (cf. Figs. 17 B, D, 18B). In addition, the merus of the third maxilliped is also rounded in P. brevi pes ( Fig. 18 A), like Gandoa zanzibarensis ( Fig. 20 C); and both have the outer surface of the chela distinctly pubescent ( Figs. 17 D, E, 19D).

Ng & Naruse (2009: 289) provisionally recognized G. brevipes as a distinct species, commenting that it appeared to differ from G. zanzibarensis in having the front less developed and the carapace proportionately broader. The examination of the lectotype of G. brevipes shows that these differences are merely a consequence of the soft carapace, with the frontal part partially compressed and the posterior margin of the carapace damaged ( Fig. 17 A, C, D). The revised measurements show both have the same carapace width to length proportions (ca. 1.4). There are no other obvious differences and we are confident Pinnixa brevipes H. Milne Edwards, 1853 , is a senior subjective synonym of Voeltzkowia zanzibarensis Lenz, 1905 . The type locality of P. brevipes ( Mayotte) is about 1000 km southeast of Zanzibar. As such, the species should now be known as Gandoa brevipes (H. Milne Edwards, 1853) .

Figures

FIGURE 4. Selwynia sibogae (Tesch, 1918). A – E, male (7.7 × 5.3 mm) (ZRC 2010.0298), Lombok, Indonesia; F – K, ovigerous female lectotype (10.9 × 6.1 mm). A, left third maxilliped; B, male abdomen; C, right P 4; D, E, left G 1; F, female abdomen; G, left P 3; H, left P 4; I, left P 5; J, right P 3; K, right P 4. Scales: A – E = 1.0 mm; F = 2.0 mm.

FIGURE 17. Selwynia brevipes (H. Milne Edwards, 1853), ovigerous female lectotype (7.6 × 5.3 mm, carapace soft) (MNHN B- 10616), Mayotte. A, overall habitus; B, frontal regions of carapace; C, ventral view of cephalothorax; D, frontal view of cephalothorax; E, outer view of left chela.

FIGURE 18. Selwynia brevipes (H. Milne Edwards, 1853), ovigerous female lectotype (7.6 × 5.3 mm, carapace soft) (MNHN B- 10616), Mayotte. A, right third maxilliped; B, right orbit and eye; C, right chela; D, right P 3; E, left P 4; F, left P 5. Scale: A, B = 0.5 mm; C – F = 1.0 mm.

FIGURE 19. Gandoa zanzibarensis (Lenz, 1905), female holotype (7.2 × 5.0 mm) (ZSM 1277 / 1), Zanzibar. A, overall habitus; B, frontal view of cephalothorax; C, ventral view of cephalothorax showing sternum and vulvae; D, outer view of left cheliped.

FIGURE 20. Gandoa zanzibarensis (Lenz, 1905), female holotype (7.2 × 5.0 mm) (ZSM 1277 / 1), Zanzibar. A, overall habitus; B, frontal view of cephalothorax; C, left third maxilliped; D, right orbit and eye; E, right P 2; F, right P 3; G, left P 5; H, abdomen. Scales = 1.0 mm. A, B, G after Lenz, 1905: pl. 47, fig. 9.