Spiralothelphusa Bott, 1968

Pati, Sameer K., Mandal, Sudipta & Jaiswal, Deepa, 2022, Description of a new species of Spiralothelphusa Bott, 1968, and redescription of Spiralothelphusa wuellerstorfi (Heller, 1862) (Decapoda: Brachyura: Gecarcinucidae), European Journal of Taxonomy 798, pp. 1-29 : 24

Illustrated key to the species of Spiralothelphusa Bott, 1968

1. G1 with longitudinally less strongly twisted (half turn) terminal segment and distal portion of subterminal segment ( Fig. 7A ) .......................................................................................................... 2

– G1 with longitudinally more strongly twisted (full turn) terminal segment and distal portion of subterminal segment ( Fig. 7B ) .......................................................................................................... 5

2. G1 tip gently curved upwards ( Fig. 7C ); G1 non-twisted portion with gently curved outer margin ( Fig. 7C )...................................................................... Spiralothelphusa hydrodroma (Herbst, 1794)

– G1 tip almost straight to gently hooked downwards ( Fig. 7D–F ); G1 non-twisted portion with strongly or sharply curved outer margin ( Fig. 7D–F )........................................................................ 3

3. Male telson with gently concave lateral margins ( Fig. 7G ); G1 non-twisted portion with sharply curved outer margin ( Fig. 7D ).......................................... Spiralothelphusa senex (Fabricius, 1798)

– Male telson with straight lateral margins ( Fig. 7H–I ); G1 non-twisted portion with regularly curved outer margin ( Fig. 7E–F ) ................................................................................................................... 4

4. Male pleonal somite 6 relatively narrower, proximal width circa 1.3 times medial length ( Fig. 7H ); male telson equal in length to male pleonal somite 6 ( Fig. 7H ); G1 non-twisted portion with relatively less strongly convex outer margin ( Fig. 7E )........................... Spiralothelphusa fernandoi Ng, 1994

– Male pleonal somite 6 relatively broader, proximal width circa 1.6 times medial length ( Fig. 7I ); male telson slightly longer than male pleonal somite 6 ( Fig. 7I ); G1 non-twisted portion with relatively more strongly convex, hump-like outer margin ( Fig. 7F ) ................................................................... ....................................................................... Spiralothelphusa gibberosa Pati & Sudha Devi, 2015

5. G1 relatively stout, with tip strongly curved upwards ( Fig. 7J ) .......................................................... ....................................................................................... Spiralothelphusa parvula (Fernando, 1961)

– G1 relatively slender, with tip gently hooked downwards ( Fig. 7K–L ) ............................................ 6

6. Male telson with concave lateral margins ( Fig. 7M ); G1 non-twisted portion with outer margin sharply, relatively less strongly curved and straight towards base ( Fig. 7K ) ...................................... .................................................................................... Spiralothelphusa wuellerstorfi ( Heller, 1862)

– Male telson with almost straight lateral margins ( Fig. 7N ); G1 non-twisted portion with outer margin regularly, relatively more strongly curved and distinctly notched towards base ( Fig. 7L ) ................. ....................................................................................................... Spiralothelphusa andhra sp. nov.

Figures

Fig. 7. Telson and G1 in Spiralothelphusa species showing diagnostic features. – A, F, I. Spiralothelphusa gibberosa Pati & Sudha Devi, 2015, holotype, ♂ (28.0 × 23.0 mm) (ZSI-WRC C.1186). – B, K, M. S. wuellerstorfi (Heller, 1862). B. ♂ (37.5 × 27.1 mm) (ZSI-WRC C.1960). K, M. Lectotype, ♂ (37.4 × 28.5 mm) (NHMW CR 27063). – C. S. hydrodroma (Herbst, 1794), topotype, ♂ (27.2 × 21.4 mm) (ZMUC CRU 2824). – D, G. S. senex (Fabricius, 1798), lectotype, ♂ (25.9 × 20.3 mm) (ZMUC CRU 4626). – E, H. S. fernandoi Ng, 1994, holotype, ♂ (35.7 × 26.5 mm) (ZRC 1984.7547). – J. S. parvula (Fernando, 1961), paratype, ♂ (19.4 × 15.0 mm) (ZRC 1984.7887). – L, N. S. andhra sp. nov., holotype, ♂ (37.8 × 30.2 mm) (ZSI-FBRC INV/2256). A–B. Left G1, apical view. C, L. Right G1, dorsal view (horizontally flipped). D–F, J–K. Left G1, dorsal view. G–I, M–N. Pleonal somite 6 and telson. Scale bars: A–F, J–L=1 mm; G–I, M–N =5 mm. C–E, G–H, J adapted from Ng & Tay (2001) and I is adapted from Pati & Sudha Devi (2015).