Tiwaripotamon pingguosense Dai & Naiyanetr, 1994

Ng, Peter K. L., 2024, Taxonomic notes on three species of Tiwaripotamon Bott, 1970 (Crustacea: Brachyura: Potamidae) from Vietnam and China, one of which is new to science, Zootaxa 5476 (1), pp. 298-313 : 305-306

Tiwaripotamon pingguosense Dai & Naiyanetr, 1994

( Figs. 6–8 )

Material examined. Holotype male (52.9 × 40.8 mm), paratype female (51.6 × 39.4 mm) ( CAS-CB 5243 ), Pingguo County, Guangxi Zhuang Autonomous Region , China, 108.7 m asl, 28 September 1977. [Photographs examined]

Diagnosis. Carapace subquadrate, wider than long ( Figs. 6A , 7A ); epigastric cristae very low, postorbital cristae low, just visible as very low ridge ( Figs. 6A , 7A ); external orbital tooth broadly triangular, separated from anterolateral margin by distinct cleft ( Fig. 7A ); epibranchial tooth distinct, rest of anterolateral margin subcristate, gently serrrate ( Fig. 7A ); suborbital margin convex, smooth, without inner tooth; suborbital region smooth, subhepatic, pterygostomial and sub-branchial regions smooth ( Figs. 6B , 7B, C ); posterior margin of epistome with low, wide median lobe, broadly triangular ( Fig. 7B ). Male thoracic sternites punctate ( Fig. 6B ); tubercle of male pleonal locking mechanism on posterior third of somite 5 ( Dai 1999: fig. 184-3). Ambulatory legs relatively long ( Figs. 6A, B , 7C ). Male pleon proportionately more quadrate, somites 3 and 4 relatively wide ( Fig. 6B ). G1 with subterminal segment gently curved outwards, outer margin gently convex; terminal segment sharply tapering, gently upcurved, basal part with low rounded lobe ( Figs. 8A–D ). Vulva large, ovate, opening slit-like, directed obliquely inwards, occupying most of sternite 6, gently pressing onto the suture with sternite 5 ( Fig. 7D ).

Females and variation. There is no substantial variation other than in characters associated with the sex of the species.

Remarks. The G1 as figured by Dai & Naiyanetr (1994: fig. 1-4–5) and Dai (1999: fig. 184-4–6) agrees with the present photographs ( Fig. 8 ) except that the latter was photographed with the structure tilted to one side. This makes the G1 appear slightly slenderer than what was figured by Dai & Naiyanetr (1994) and Dai (1999), with the basal dorsal flap on the terminal segment also relatively larger ( Fig. 8 ) (see Remarks for next species).

Figures

FIGURE 6. Tiwaripotamon pingguosense Dai & Naiyanetr, 1994, holotype male (52.9 × 40.8 mm) (CAS-CB 5243), China. A, overall dorsal habitus; B, ventral view of habitus.

FIGURE 7. Tiwaripotamon pingguosense Dai & Naiyanetr, 1994.A, B, holotype male (52.9 × 40.8 mm) (CAS-CB 5243), China; C, D, paratype female (51.6 × 39.4 mm) (CAS-CB 5243), China. A, dorsal view of carapace; B frontal view of cephalothorax; C, ventral view of habitus; D, female sternopleonal cavity and vulvae.

FIGURE 8. Tiwaripotamon pingguosense Dai & Naiyanetr, 1994, holotype male (52.9 × 40.8 mm) (CAS-CB 5243), China. A, right G1 (ventral view); B, right G1 (dorsal view); C, distal part of right G1 (ventral view); D, distal part of right G1 (ventral view).