Chiromantes boulengeri ( Calman, 1920 )

Naderloo, Reza, 2011, Grapsoid crabs (Decapoda: Brachyura: Thoracotremata) of the Persian Gulf and the Gulf of Oman, Zootaxa 3048, pp. 1-43 : 15-16

Chiromantes boulengeri ( Calman, 1920)

( Figs. 6 a–f, 7a, b)

Sesarma boulengeri Calman, 1920: 63 , Fig. A.

Chiromantes boulengeri — Apel & Türkay 1999: 133. — Apel 2001: 116. — Ng et al. 2008: 220 (list), 223. — Naderloo & Schubart 2009: 63 , figs. 2, 3.

Type locality. Basra, Iraq, Persian Gulf

Material examined. Lectotype: Iraq: 1 male (NHM 2002.298, CL 23.4, CB 27.00 mm), Ashar Creek, Basra, coll. C.H. Boulenger, 1919. Paralectotypes: 1 male, 2 females (ovig.) (NHM 2002.299-301), same locality data as holotype.

Others: Iraq: 1 male, 1 female (NHM 1892.9.16.7.20), Shat al Arab, FAO, det. M. Apel, 28.10.1997; 1 male (NHM 1999.124), Shat al Arab, FAO, det. M. Apel, 28.10.1997. Iran: 3 males ( ZUTC Brach1151), Bahmanshir River, Abadan, summer 2006, E. Gholinezhad; 1 male, 1 female ( ZUTC Brach1153), same data; 18 males, 27 females (16 ovig.), 3 juv. ( SMF 33818), Pole Tanki Abolhassan, Bahmanshir River, Abadan, 30º 21' 0 1.5ʺN, 48º 18' 35.9ʺE, coll. R. Naderloo & A. Kazemi, 20.05.2008; 1 female (ovig.) ( SMF 38454), Yadman-Valfajr, Arvandroud River, Khuzestan, coll. 20.05.2008.

Redescription. Carapace quadrate ( Figs. 6 a, 7a), slightly broader than long (CL/CB about 1.17–1.20); carapace slightly convex, short setae scarcely scattered on posterior surface of carapace, denser on posterolateral regions. Regions well defined, prominent groove separating gastric from cardiac region, oval groove in hepatic region immediately behind of orbit; 8 smooth ridges of different length on lateral region, 2 short ridges in between. Front strongly flexed downwards, 4 lobes in frontal region, median 2 larger than lateral 2; frontal edge nearly bilobed; lateral angles of front rounded ( Fig. 6 a).

Chelipeds equal, sometimes subequal, distinctly large; Merus outer surface with finely granular transverse ridges, inner margin dentate on two-thirds of proximal part, subdistally roundly expanded; carpus with spineshaped tooth on inner margin. Palm ( Fig. 6 b) massive, oblique granular ridges proximally on lower margin; outer surface with small granules, becoming larger medially; upper margin with 2 or 3 longitudinal granular ridges; inner surface with oblique row of relatively large granules extending from base of immovable finger towards upper part.

Fingers with small gap in between, widening distally; movable finger longer than palm, with small granules proximally on dorsal margin; tips of fingers pectinated, scalloped; tip of movable finger nearly tridentate. Female cheliped small, narrow, otherwise similar to male.

Merus of walking legs with granular transverse ridges on upper surface, upper surface of last legs nearly smooth, with few ridges on anterior part; anterior margin with subdistal tooth. Carpus with 2 carinae on posterior surface, one on anterior surface; anterior margin of carpus, propodus densely covered with short brown setae. Propodus slightly longer than carpus, one carina on posterior surface, one carina on anterior surface.

Male abdomen ( Fig. 6 c) broadly triangular; sixth somite longer than fifth, with arched anterodistal margin; telson longer than sixth somite, lateral margin proximally nearly straight, strongly convex distally.

G1 ( Fig. 6 d) straight, inner margin distally roundly expanded; terminal pectinated part gently bent laterally, small pectinated process ( Fig. 6 e), nearly triangular; long setae covered terminal part, not fully concealed it.

Female gonopore ( Fig. 6 j) in depression on anterior edge of fifth abdominal sternite, attached to posterior margin of fourth sternite; with elevated small operculum, directed outward.

Remarks. Calman (1920) briefly described this species from the Shat al Arab River, Basra, Iraq, and assigned it to Sesarma Say, 1817 . Apel & Türkay (1999) placed C. boulengeri in Chiromantes Gistel, 1848 , following the comments by Holthuis (1977). Ng & Liu (1999) remarked on the composition of Chiromantes and suggested that the genus is heterogeneous, which was later supported by the molecular findings of Naderloo & Schubart (2009). Chiromantes is currently being revised by P. Ng and C. Schubart in an ongoing molecular and morphological study of the genus and its allies. Ng et al. (2008), however, considered that the Indo-West Pacific Chiromantes dehaani (H. Milne Edwards, 1853) , should be referred to a separate genus together with C. boulengeri ( Calman, 1920) , Pseudosesarma patshuni (Soh, 1978) , P. crassimanum ( De Man, 1887) , P. johorensis (Tweedie, 1940) , P. moeschi ( De Man, 1888) , Sesarmops sinense (H. Milne Edwards, 1853) , and S. intermedium ( De Haan, 1835) . While Naderloo & Schubart (2009) confirmed that C. boulengeri should be moved to a new genus, its affinities with the other species are less obvious, with C. boulengeri separating out from C. haematocheir (type species of Chiromantes ) and others.

Biology. Chiromantes boulengeri is a medium-size species (largest male CL = 23.23 mm, CB = 27.20 mm, largest female CL = 24.52 mm, CB = 29. 0 7 mm) inhabiting the Arvandroud (Shat al Arab) and Bahmanshir rivers, where it lives in burrows (about 30 cm in depth) on the muddy banks. The species dominates the wetlands along the rivers where found among Phragmites spp. reeds. This sesarmid is apparently endemic to the region and occurs in upstream the rivers although its distribution along the rivers is not well documented ( Naderloo & Schubart 2009).

Ovigerous females first appear in late March or early April, reaching the maximum proportion in August, when they comprise 60% of all adult females. The smallest ovigerous females are measure of 17.7 mm in CB, and males reach their maturity at the same size as females, but showed slightly rapid growth than females ( Ali 1979).

During May and June the population comprises the highest number of the adult individuals (about 90–92% of the total population) with the CB ranging between 25 to 27.5 mm. Juveniles (CB <2 mm) are appearing in July, and are most abundant in July and August when they are recorded to be 7.5–10% of the population. In December, when the temperature is particularly low in the region, most crabs are inactive and remain in their burrows. Moulting also does not occur during November–January ( Ali 1979).

Colour. Live specimens are dark gray on the dorsal surface of the carapace. Walking legs are slightly brighter than carapace. Chelipeds are white to light brown from anterior view, granules on palm and fingers distinctly white, lower and inner portions of the palm are sometimes pale orange. The ventral surface of the carapace is bright and the abdomen is distinct by its light brown colour ( Naderloo & Schubart 2009).

Regional records. PERSIAN GULF: Basra, Iraq ( Calman 1920); Arvandroud and Bahmanshir rivers, Iran ( Naderloo & Schubart 2009).

Geographical distribution. This species is apparently endemic to the northern Persian Gulf, being located in Iraq in the high reaches of Shat al Arab, Euphrates, Tigris, and in Iran along Arvandroud and Bahmanshir rivers catchments ( Naderloo & Schubart 2009).

Figures

FIGURE 6. Chiromantes boulengeri (Calman, 1920), male (SMF 33818): a – e; female (SMF 33818): f. a, posterior surface of carapace; b, cheliped of male, outer surface; c, male abdomen; d, G 1, lateral surface (right); e, apical part of G 1, lateral surface; f, female gonopore (right).