Pseudolitochira Ward, 1942

Ng, Peter K. L., Clark, Paul F., Clark, Brett & Kamanli, Seyit A., 2021, Pseudolitochira integra (Miers, 1884) (Crustacea: Brachyura: Pilumnidae): redescribed and illustrated from micro-CT scanning the type female, Zootaxa 4969 (2), pp. 377-391 : 378-381

Genus Pseudolitochira Ward, 1942

Pseudolitochira Ward, 1942: 100 ; Ng 1987: 97; Ng et al. 2008: 144.

Type species. Carcinoplax integra Miers, 1884 , by present designation.

Diagnosis. Carapace transversely subovate ( Figs. 3A , 4A , 5A ); surface covered with short pubescence, never with long setae; regions on dorsal carapace surface almost undiscernible, with only shallow H-shaped gastric grooves barely visible ( Fig. 5A ); front margin wide, bilobed, no lateral lobule present, confluent with supraorbital margin ( Fig. 5A ); anterolateral margin relatively short, entire, with small granules ( Fig. 5A ); posterior margin of epistome almost entire, with median lobe triangular with shallow median cleft, confluent with lateral margins ( Fig. 5B ); third maxilliped with short, subrectangular ischium, merus quadrate, anteroexternal angle rounded, not auriculiform ( Fig. 5D ); ambulatory legs proportionately slender, long, with distinct dactylo-propodal lock ( Figs. 3A–C , 4A, B ); female pleonal somite longitudinally narrow, wide, reaching to coxae of last ambulatory legs, somite 1 tapering along lateral margins ( Fig. 5E ); vulvae large, subovate, occupying anterior two-thirds of sternite 6, touching suture with sternite 5 ( Fig. 3D ).

Remarks. Ward (1942: 52) established Pseudolitochira for C. integra without examining the type female specimen from Seychelles and only provided a brief diagnoses for his new genus: “Carapace broader than long, almost flat, regions not defined. Anterolateral margins entire or with rudimentary teeth. Front less than half the width of the carapace, abruptly declivous. Antennae standing in the orbital hiatus. Chelipeds equal in size” ( Ward 1942: 100). He ( Ward 1942) considered that Pseudolitochira was close to Litochira Kinahan, 1856 . Litochira , however, is not a pilumnoid, and is currently assigned to its own goneplacoid family, Litocheiridae Kinahan, 1856 (see Türkay 1983; Castro et al. 2010; Guinot et al. 2013).

Ward (1942: 101) also compared Pseudolitochira to Heteropilumnus De Man, 1895 , noting it differed in possessing a relatively wider frontal margin, the regions of the carapace surface are not defined, the anterolateral margin is entire or almost so, and the carapace and pereiopods have fewer setae. Recently, Ng et al. (2018: 2) commented that Pseudolitochira differs markedly from Heteropilumnus in possessing a carapace that is transversely subovate ( Figs. 3A , 4A , 5A ) (vs. subquadrate in Heteropilumnus ); the regions on its dorsal carapace surface are almost undiscernible ( Fig. 5A ) (vs. regions visible in Heteropilumnus ); the front is proportionately wide with anterolateral margin short ( Fig. 5A ) (vs. proportionately narrower front with wider anterolateral margins in Heteropilumnus ); there is no trace of a lateral lobule on the front, with the margin confluent with the supraorbital margin ( Fig. 5A ) (vs. frontal margin with a low lateral lobule in Heteropilumnus ); the anterolateral margin is entire ( Fig. 5A ) (vs. at least some of the anterolateral margin with low teeth or lobes in Heteropilumnus ); and the posterior margin of the epistome is almost entire, with median lobe triangular and confluent with the lateral parts ( Fig. 5B ) (vs. the posterior margin has three distinct parts, with the median lobe separated from the lateral parts by a deep fissure in Heteropilumnus ). This was based on their (Ng et al. 2019: 2) examining the holotype of P. integra and specimens of the type species of Heteropilumnus , H. stormi De Man, 1895 .

Ward (1942) listed two Pseudolitochira species ( Carcinoplax integra Miers, 1884 , and Litocheira decharmoyi Bouvier, 1915 ), but he did not formally select a type species. Ng et al. (2008: 144) incorrectly assumed Carcinoplax integra Miers, 1884 , to be the type species of the genus by monotypy. Carcinoplax integra Miers, 1884 , is here formally selected as the type species of Pseudolitochira Ward, 1942 and as such will retain the concept of the genus as recognised by Ng (1987). Litocheira decharmoyi was transferred to Heteropilumnus by Ng et al. (2018) (see also Maenosono 2019: 23, figs. 1B, 3, 6B, 14C, D).

Figures

FIGURE 3. Pseudolitochira integra (Miers, 1884), holotype female (4.9 × 3.4 mm) (NHM 1882.24), Seychelles. A, overall dorsal view; B, left fourth ambulatory leg; C, left ambulatory propodus and dactylus; D, sternopleonal cavity and vulvae.

FIGURE 4. Pseudolitochira integra (Miers, 1884), holotype ♀ (4.9 × 3.4 mm), NHM 1882.24, Seychelles. A, overall dorsal view; B, ventral view of cephalothorax.

FIGURE 5. Pseudolitochira integra (Miers, 1884), holotype ♀ (4.9 × 3.4 mm), NHM 1882.24, Seychelles. A, dorsal view of carapace; B, frontal view of cephalothorax; C, outer view of right chela; D, buccal cavity, third maxillipeds and thoracic sternites