Perisesarma guttatum ( A. Milne-Edwards, 1869 )

Naderloo, Reza, 2011, Grapsoid crabs (Decapoda: Brachyura: Thoracotremata) of the Persian Gulf and the Gulf of Oman, Zootaxa 3048, pp. 1-43 : 29-31

Perisesarma guttatum ( A. Milne-Edwards, 1869)

( Figs. 7 e–f, 14a–e)

Sesarma guttatum A. Milne-Edwards, 1869: 26 .

Sesarma (Chiromantes) guttatum — Crosnier 1965: 68, figs. 94, 97, 106.

Sesarma (Perisesarma) guttatum — Holthuis 1977: 171.

Sesarma guttatum — Vannini & Volmori 1981: 87, figs. 17D, 18D, 19C.

Perisesarma guttatum — Hywel - Davies 1994: 29, 37, 48, App. 4. — Apel 2001: 119, 120. — Gillikin & Schubart 2004: 440, fig. 4a, b.

Type locality. Zanzibar

Material examined. GULF OF OMAN, UAE: 2 males, 1 female ( SMF 37370), mangroves, Khor Kalba, Fujairah, 25º 01'N, 56º 21'E, M. Apel, 0 1.07.1995. INDIAN OCEAN Kenya: 1 male, 1 female ( SMF 29337), Minda Greek, Dabaso, Watamu, S. of Malindi, 30º 28'N, 49º 11'E, coll. D.P. Gillikin & A. Verheyden, 09–11.1998; 1 male ( SMF 31835), Mida Creek, D.P. Gillikin & A. Verheyden, 08.1998–10.1999. South Africa: 4 males ( SMF 31835), Umlazi Lagoon, Natal, coll. Neumann, Jul. 1997.

Redescription. Carapace subquadrate ( Figs. 7 e, 14a), moderately wider than long (CB/CL = 1.2), maximum breadth between exorbital angle; carapace regions nearly distinct, gastric region distinctly defined; 6 curved ridges on posterolateral region, small transverse ridges scarcely on carapace, ridges with short setae; frontal region sharply deflexed, 4-lobed, median 2 larger than lateral 2, with deep groove between them; medians separated from laterals by shallow groove. Frontal edge clearly longer than posterior edge of carapace, distinctly 2-lobed, lobes separated by wide notch. Supraorbital margin smooth, without fissure; infraorbital margin minutely granular with small granules. Lateral margin of carapace with 2 teeth including exorbital angle; first one elongately triangular, directed forward, with curved lateral margin, second one small triangle; posterolateral margin nearly straight, slightly concave medially. Third maxilliped long with large gap between; ischium, merus subequal in length.

Chelipeds subequal, large; merus with granular margins; upper margins with large subdistal tooth, that of inner margin large; outer surface with granular transverse ridges. Carpus subquadrate, outer surface with granular transverse ridges. Manus ( Fig. 14 b) with 2 prominent pectinated carinae distally on upper surface, granular line behind them; outer surface granular, granules on curved line proximally; lower, upper margins granular, upper margin nearly sharply running proximally; inner surface with granules slightly larger than those of outer surface. Movable finger with 12 large tubercles along upper surface ( Fig. 14 b), row of small tubercles on half proximal part of upper surface of movable finger along inner part of large tubercles, distinct ridge proximally on inner surface of movable finger; cutting edge of fingers with large obtuse teeth, one median, one subdistal tooth distinct on both fingers; tip of movable finger with 2, unmovable finger with 3 tooth-like processes. Female chelipeds smaller than those of males, without pectinated crests.

Walking legs flattened, broad; merus broad, with subdistal spine on anterior margin, upper surface with short transverse ridges, merus of third leg about 2.2 times as long as broad; carpus with 2 carinae on outer, one carina on inner surface; propodus with one carina on outer, one on inner surface, propodus of third leg about 3.5 times as long as broad; carpus, propodus of last walking legs without carina on inner surface, brown setae densely on anterior, posterior margins of propodus and distal carpus; dactylus smooth, without spine, with brown setae along margins proximally.

Male abdomen ( Fig. 14 d) with sixth somite longest, slightly diverging proximally, sharply curved distally; telson about as long as broad, slightly shorter than sixth somite.

G1 ( Fig. 14 c) quite straight, slightly tapering distally, distinct longitudinal suture along ventrolateral surface; apical chitinous process long, curved outwards at 60º angle, apically 2-lobed, ventral lobe longer, apically round; distal opening subdistally on dorsal surface of apical process; long brown setae distally on lateral margin, patch of long brown setae distally on mesial margin, long setae around terminal process, some short ones scarcely along lateral, ventral margins.

Female gonopore ( Fig. 14 e) in inner part of fifth sternal somite; strongly depressed; with long narrow operculum directing dorsally.

Remarks. Perisesarma guttatum is relatively similar to P. p er s ic um, the most common species in the Persian Gulf mangroves. Species of Perisesarma are distinguishable from those of Parasesarma by having an anterolateral tooth on the carapace. Perisesarma guttatum is closely allied to P. samawati , although genetically distinct and not sister species. The carapace of P. s a m a w a t i is dark with blue spots, and this species has 7–9 tubercles on the upper surface of the movable finger, while such pigmentation is absent in P. guttatum and there are 9–11 tubercles on the upper surface of movable finger. Another difference is in the form of the G1, which the apical chitinous process of P. guttatum is bent slightly more than in P. Samawati , which is at about a 45º angle ( Gillikin & Schubart 2004).

Biology. Perisesarma guttatum is a medium-size species. All three specimens collected by M. Apel from Fujairah in the Gulf of Oman are small in size (largest male CL = 10.62 mm, CB = 12.90 mm, ovigerous female CL = 6.24 mm, CB = 8.18 mm). This species is one of the dominant species of mangroves in the Gulf of Oman ( Hywel-Davies 1994). It should be remarked that Hywel-Davies (1994) did not record Metopograpsus messor and P. persicum from these regions, which are common species in the Persian Gulf (Cooper 1977; Apel & Türkay 1999; Naderloo & Schubart 2010; present study) and north Gulf of Oman in the Iranian coast ( Naderloo & Schubart 2010; present study). These two species seems to have been replaced by P. guttatum and M. thukuhar in the southern Gulf of Oman ( Hywel-Davies 1994). Perisesarma guttatum has also been recorded from the mangroves of Melita Bay in the Red Sea, where it occurs on the trunk of A vicennia marina together with Metopograpsus thukuhar ( Holthuis, 1977) . Perisesarma guttatum is common in the East Africa mangroves ( Hartnoll 1975; Vannini & Valmori 1981; Crosnier 1965; Gillikin & Schubart 2004) and is sympatric with its conger P. s a m a w a t i Gillikin & Schubart, 2004. However, P. guttatum occurs extensively and is distributed widely in East Africa ( Gillikin & Schubart 2004).

Colour. Vannini & Valmori (1981) briefly described the colour pattern of live P. guttatum from Kenya: posterior surface of the carapace dark violet, walking legs light violet; chelipeds dark violet on the proximal part and upper surface, distally getting red, inner surface of the chelipeds red-orange. An alcohol-preserved specimen collected from Kenya in 1998 still shows the general colour pattern described by Vannini & Valmori (1981), although the preserved specimens have brighten cheliped.

Regional records. GULF OF OMAN: Muscat ( Hywel-Davies 1994), UAE ( Apel 2001). There is no record of this species from the Persian Gulf.

Geographical distribution. Western Indian Ocean (excluding the Persian Gulf): South Africa, Madagascar, Tanzania, Kenya, Somalia, Red Sea, southwestern Gulf of Oman.

Figures

FIGURE 14. Perisesarma guttatum (A. Milne-Edwards, 1869), male (SMF 37370): a – d; female (SMF 37370): e. a, posterior surface of carapace; b, cheliped of male, outer surface; c, G 1, ventral surface (right); d, male abdomen; e, female gonopore (right).

FIGURE 7. a, Chiromantes boulengeri (Calman, 1920), male (SMF 33818); b, the same species in its habitat in Bahmanshir River, Iran (photo by E. Gholinejad); c, Parasesarma persicum Naderloo & Schubart, 2010, male (SMF 38458, CL = 24.34 mm, CB = 30.16 mm); d, the same species in its habitat in Khalij-Nayband, Persian Gulf (photo by R. Naderloo); e, Perisesarma guttatum (A. Milne-Edwards, 1869), male (SMF 29337, CL = 18.70 mm, CB = 22.49 mm); f, the same specimen from ventral view.