Parasesarma indiarum ( Tweedie, 1940 )

Shahdadi, Adnan, Ng, Peter K. L. & Schubart, Christoph D., 2018, Morphological and phylogenetic evidence for a new species of Parasesarma De Man, 1895 (Crustacea: Decapoda: Brachyura: Sesarmidae) from the Malay Peninsula, previously referred to as Parasesarma indiarum (Tweedie, 1940), Raffles Bulletin of Zoology 66, pp. 739-762 : 750-752

Parasesarma indiarum ( Tweedie, 1940)

( Figs. 2B , 3B , 7–9 )

Sesarma bidens var. indica De Man, 1902: 541 (preoccupied name).

Sesarma (Chiromantes) bidens indica: Tesch, 1917: 135 .

Sesarma (Chiromantes) indiarum: Campbell, 1967: 5 (in key).

Sesarma bidens indiarum Tweedie, 1940: 93 (replacement name for Sesarma bidens var. indica De Man, 1902 ; pre-occupied by Sesarma indica H. Milne-Edwards, 1837 ).

Sesarma (Chiromantes) indiarum: Serène, 1968: 107 .

Perisesarma indiarum: Lim et al., 2008: 106 ; Ng et al., 2008: 222 (in list); Davie, 2010: 205 (in key); Shahdadi & Schubart, 2015: 1084 (table).

Parasesarma indiarum: Shahdadi & Schubart, 2017: 535 .

Material examined. Lectotype: 1 male (29.0 × 25.0 mm) ( RMNH. CRUS. D.141), Ambon Moluccas, Indonesia, coll. 1863 (= S 146 in Table 1) . Paralectotypes: 2 males, 2 females ( RMNH. CRUS. D.141) , 11 males, 1 female ( RMNH. CRUS.

D.19), same locality as lectotype. Other material: 6 males (largest 13.5 × 10.8 mm, 13.1 × 10.5 mm), 5 females (largest, ovigerous, 13.5 × 10.8 mm) ( ZRC 2018.0737 ), Passo, Teluk Ambon, Ambon, Moluccas, Indonesia, coll. D.A. Nugroho, 26 March 2013 .

Diagnosis. Medium-size species (up to 30 mm carapace width); carapace subrectangular, slightly broader than long. Front moderately deflexed, with broad, relatively deep, median concavity, postfrontal lobes prominent, median lobes broader than lateral ones, separated by median furrow; dorsal carapace regions clearly indicated, anterolateral margin with sharp exorbital angle and well-developed epibranchial tooth. Chelipeds homochelous; large in males, upper surface of palm with 2 transverse pectinated crests, dorsal surface of dactylus with 10–12 low, distinct, transversely broad tubercles without transverse sulcus. Ambulatory legs relatively short, broad. Male pleon triangular with telson slightly longer than basal width. G1 relatively long, straight, apical corneous process long, bent at angle of about 60° to longitudinal axis, arched in cross section, aperture subterminal. Female pleon broadly rounded, vulva in anterior edge of sternite 6, with operculum rounded.

Remarks. The species has long been part of Perisesarma until Shahdadi & Schubart (2017) placed it in Parasesarma . The type material of Sesarma bidens var. indica De Man, 1902 , was collected in 1863 from Ambon Moluccas, Indonesia, by E. W. A. Ludeking, and deposited in two separate jars in the RMNH. All specimens are syntypes, as De Man (1902) did not select a holotype. As Tweedie (1940) proposed Sesarma bidens indiarum as a replacement name for De Man’s (1902) subspecies, all of De Man’s syntypes are the types for Tweedie’s taxon. As part of our revision of the genera Parasesarma and Perisesarma , the best preserved male specimen is here selected as the lectotype of the species (see also Shahdadi & Schubart, 2017: table 1).

The records of “ P. indiarum ” from Borneo, Sumatra and Java and New Guinea ( Tesch, 1917; Tweedie, 1936, 1940, 1950) all need to re-examined in the context of the present restriction of the species for the population in Ambon. The material from Borneo (Labuan) are slightly different morphologically from both P. indiarum sensu stricto and P. peninsulare new species, and its status will need to be re-evaluated.

Distribution. Parasesarma indiarum was originally described from Ambon and Ternate islands ( Indonesia) (De Man, 1902) and later reported from New Guinea, south coast of Java ( Tesch, 1917), Singapore, both coasts of the Malay Peninsula, West Sumatra ( Tweedie, 1936, 1940) and Labuan in Borneo ( Tweedie, 1950). As noted above, only the record from the type locality ( Ambon) is P. indiarum sensu stricto with those from the Malay Peninsula referred to a new species instead.

Figures

Fig. 2. Comparisons of male chelar dactylus and tuberculation patterns, outer views. A, Parasesarma peninsulare new species, holotype male (25.5 × 22.2 mm) (ZRC 2017.1075); B, P. indiarum, paralectotype male (22.8 × 19.4 mm) (RMNH. CRUS. D.19); C, P. eumolpe, neotype male (17.4 × 14.7 mm) (ZRC 2018.0249); D, P. eumolpe, male (24.3 × 20.7 mm) (SMF 49922); E, P. foresti, paratype male (16.6 × 14.4 mm) (ZRC 2003.0481); F, P. messa, paratype male (18.6 × 16.0 mm) (QM-W2452).

Fig. 3. Comparisons of male chelar dactylus and tuberculation patterns, dorsal views. A, Parasesarma peninsulare new species, holotype male (25.5 × 22.2 mm) (ZRC 2017.1075); B, P. indiarum, paralectotype male (22.8 × 19.4 mm) (RMNH. CRUS. D.19); C, P. eumolpe, male (24.3 × 20.7 mm) (SMF 49922); D, P. foresti, paratype male (16.6 × 14.4 mm) (ZRC 2003.0481); E, P. messa, paratype male (18.6 × 16.0 mm) (QM-W2452).

Fig. 7. Parasesarma indiarum, lectotype male (29.0 × 25.0 mm) (RMNH. CRUS. D.141). A, overall habitus; B, carapace, dorsal view; C, anterior thoracic sternum and pleon; D, pleon; E, posterior thoracic sternum and pleon.

Fig. 8. Parasesarma indiarum, lectotype male (29.0 × 25.0 mm) (RMNH. CRUS. D.141). A, carapace, front view; B, left chelar pectinated crests; C, right chela, outer view; D, right chela, dorsal view; E, left G1, ventral view; F, denuded left G1, apical part, ventral view; G, front view of apical part of G1 and aperture.

Fig. 9. Parasesarma indiarum. A–E, male (13.5 × 10.8 mm) (ZRC 2018.0737); F, G, male (13.1 × 10.5 mm) (ZRC 2018.0737); H, I, ovigerous female (13.5 × 10.8 mm) (ZRC 2018.0737). A, carapace, front view; B, anterior thoracic sternum and pleon; C, chelae dactylar tubercles; D, left chela, outer view; E, left chelar pectinated crests; F, left G1, ventral view; G, denuded left G1, apical part, ventral view; H, pleon; I, vulvae.