Nanosesarma jousseaumei ( Nobili, 1905 )

Naderloo, Reza, 2011, Grapsoid crabs (Decapoda: Brachyura: Thoracotremata) of the Persian Gulf and the Gulf of Oman, Zootaxa 3048, pp. 1-43 : 22-26

Nanosesarma jousseaumei ( Nobili, 1905)

( Figs. 10 a–e, 9b, 11b, 12b)

Sesarma (Sesarma) jousseaumei Nobili, 1905: 411, 1906b: 323 , pl. 8, fig. 9.

Sesarma (Sesarma) jousseaumei —Lauri 1915: 416. — Guinot 1967: 283.

Nanosesarma jousseaumei — Holthuis 1977: 172. — Ng et al. 2008: 221 (list), 224. — Naderloo & Türkay 2009: 2918 , figs. 1, 4.

Nanosesarma minutum — Crosnier 1965: 70, figs. 109–115 [not Sesarma minutum De Man, 1887 ]. — Vannini & Valmori 1981: 82, fig. 15 [not Sesarma minutum De Man, 1887 ].

Type locality. Djibouti and Obock (Gulf of Aden).

Material examined. Lectotype: 1 male ( MNHN B16696 ), Mer Rouge, coll. Dr. Jousseaume, 1897. Paralectotype: 1 female ( MNHN B16696 ), Mer Rouge, coll. Dr. Jousseaume, 1897.

Others: PERSIAN GULF, Iran: 1 male ( ZUTC Brach1161), sandy/rocky, Moghdan village, 35 km E. of Parsian, Hormozgan, 27° 06'N, 53° 03'E, coll. R. Naderloo, 12.05.2006; 2 males, 5 females (3 ovig.) ( ZUTC Brach1162), rocky bed, 10 km E. of Salakh, Qeshm I., 26° 40'N, 55° 44'E, coll. R. Naderloo & A. Kazemi, 11.05.2008; 1 female ( SMF 34380), sandy/rocky, S. coast, Qeshm I., 26° 35'N, 55° 28'E, coll. R. Naderloo & A. Kazemi, 07.05.2008; 1 male, 2 females ( ZUTC Brach1163), sandy/cobble, S. coast, Qeshm I., 26° 51'N, 56° 08'E, coll. M. Türkay & R. Naderloo, 10.01.2008; 4 males, 2 females ( SMF 37689), rocky bed, 5 km W. of the city Qeshm, Qeshm I., coll. R. Naderloo & A. Kazemi, 25.10.2009; 1 male ( SMF 37688), Zeytun (olive) park, Qeshm I., 27º 11'N, 56º 24'E, coll. M. Türkay & R. Naderloo, 0 8.01.2008.

GULF OF ADEN, Djibouti: 1 male, 3 females ( SMF 25147), under stones, intertidal zone, Plage de Triton, City of Djibouti, coll. A. Allspach, G. Fischer & M. Türkay, 18.03.1987.

INDIAN OCEAN, Tanzania: 4 males, 2 females (1 ovig.) (NHM1973: 89), rocky cliff, Dar es Salam, coll. R. G. Hartnoll, April 1972, as Nanosesarma minutum . Madagascar: 1 male ( MNHN B16193 ) intertidal, Nosy Bé, coll. A. Crosnier as Nanosesarma cf. minutum ; 1 male, 1 female ( MNHN B16195 ), intertidal oyster bank, Nosy Bé, coll. A. Crosnier as Sesarma (cf) minutum Man ; 2 females ( MNHN B16196 ), sand stone beds, intertidal, Nosy Bé, coll. A. Crosnier as Sesarma cf. minutum ; 2 males, 1 female ( MNHN B16194 ), intertidal, Plante collection, Tuléar, coll. A. Crosnier as Sesarma cf. minutum .

Redescription. Carapace square ( Fig. 10 a), slightly broader than long (CB/CL = 1.1), nearly uneven, smooth, covered with short plumose setae. Regions well defined, frontal region with two lobes, distinct depression separating gastric region from cardiac; one weakly granular oblique ridge on posterolateral surface of carapace, one short ridge on anterolateral surface. Frontal region gently deflexed downward, frontal ridge about half as broad as carapace, weakly serrated, nearly bi-lobed. Orbit about one-fourth carapace breadth. Anterolateral margin with 2 teeth including exorbital angle, first broadly triangular; second small triangular, with pointed tip, lateral border behind second tooth slightly convergent ( Fig. 9 a). Basal antennal segment ( Fig. 10 b) long, reaching to base of flagellum.

Chelipeds subequal. Merus outer surface with small tubercles; inner surface smooth; posterior, anterior, lower margins granular; anterodistal margin with rectangular process. Palm relatively large, outer surface fully covered with dense setae ( Fig. 10 c); 3 rows of tubercles underneath setae ( Fig. 10 d), lower one extending from proximal part to basal third length of immovable finger, middle one short, oblique, upper row short, with irregular granules, nearly parallel to median one; lower margin smooth; upper margin with small tubercles; inner surface smooth on lower part, some tubercles on upper part. Fingers slightly narrow, shorter than palm, large gap proximally between them. Movable finger nearly straight, small granules proximally on upper surface, large distinct tubercle proximally on outer surface ( Fig. 10 d); cutting edge of fingers with different-size teeth, cutting edge of immovable finger with large prominent tubercle in middle part; tips of fingers spoon-shaped.

Walking legs merus with anterior margin weakly serrated, with small subdistal spine; posterior margin ( Fig. 10 e) with distinct tooth-shaped granule, some small ones distally to large one; posterodistal margin with spiniform teeth, proximal one largest. Propodus about twice as long as width or slightly longer, about 1.5 times as long as dactylus. Dactylus with 6 spines in 2 rows along posterior margin, larger distally; all segments of walking legs, except dactylus, densely covered with short plumose setae, long bristles between them.

Male abdomen ( Fig. 10 f) with sixth somite about 3.5 times as broad as long, lateral margin gently converging distally; telson slightly longer than broad.

G1 ( Figs. 9 b) straight, with long corneous distal part, slightly bending outward, distal opening on posterior surface of apical part.

Remarks. This species has had a long taxonomic history since its description by Nobili (1905). Serène & Soh (1970) synonymised it with N. Minutum , and Crosnier (1965) identified specimens of Nanosesarma from Madagascar as N. minutum . Holthuis (1977) re-described the species using one small female and also mentioned that the Madagascar material recorded by Crosnier (1965) was probably identical with N. jousseaumei . Naderloo & Türkay (2009) recorded this rare species from the Persian Gulf and re-described it from male specimens. They also discussed the identity of the Madagascar material identified by Crosnier supporting the view of Holthuis (1977) in assigning them to N. jousseaumei .

Nanosesarma jousseaumei is more similar to N. minutum among congeners (see Naderloo & Türkay 2009). Two characters distinguish these two species: distinct teeth-shaped tubercles including a large one present on the posterior margin of the last walking legs of N. jousseaumei ( Fig. 10 e) but finely serrated in N. minutum ; a large tubercle present on the outer surface of the movable finger, smooth in N. minutum . In addition, two other characters were used in the present study to distinguish N. jousseaumei from N. minutum and N. sarii . The lateral margin of the G1 is distally expanded with a nearly angled margin in N. jousseaumei whereas it is slightly expanded and distally arched in N. sarii , and narrowing distally in N. minutum which is completely distinct from two others ( Fig. 9 a–c). The three species are not readily distinguishable with regards to the median tooth plates of the gastric mill, all having three teeth on the posterior part of the plate, but the middle tooth being narrower than the others in N. jousseaumei ( Fig. 11 a–c); whereas the median tooth plate has lateral margins relatively arched medially in N. minutum ; posteriorly nearly straight and anteriorly converging in N. Jousseaumei , and with an intermediate form in N. sarii .

Biology. This small-size species (male lectotype CL = 4.8 mm, CB = 5.3 mm, female Paralectotype CL = 4.0 mm, CB = 4.5 mm), like its congener, N. minutum , is found under the small stones on rocky shores or between the branches of dead corals. Nanosesarma jousseaumei is not common, being only occasionally found in some rocky substrates. Vannini & Valmori (1981) recorded this species (identified as N. minutum ) from decayed woods in the muddy substrate of mangroves. Little is known about the life history of the species.

Colour. Live specimens from the Persian Gulf are generally bright-brown on the upper surfaces of the carapace and appendages, with some irregular dark-brown flecks on the anterior region of the carapace. Short brown setae on the appendages give a dark appearance to these structures ( Naderloo & Türkay 2009).

Regional records. PERSIAN GULF: Iran ( Naderloo & Türkay 2009; present study).

Geographical distribution. Western Indian Ocean: Madagascar, Tanzania, Gulf of Aden, Djibouti, Persian Gulf.

Figures

FIGURE 9. SEM photos of G 1 with enlarged apical part, lateral surface. a, Nanosesarma sarii Naderloo & Türkay, 2009, (SMF 37698); b, Nanosesarma jousseaumei (Nobili, 1905) (SMF 37689); c, Nanosesarma minutum (De Man, 1887) (SMF 30920).

FIGURE 10. Nanosesarma jousseaumei (Nobili, 1905), male lectotype (MNHN B 16696) a, posterior surface of carapace; b, basal segment of first and second antenna; c, cheliped of male, outer surface; d, cheliped of male, outer surface with detached setae patch; e, third walking leg of male (left); f, male abdomen.

FIGURE 11. SEM photos of median tooth plate of the gastric mill, ventral face. a, Nanosesarma sarii Naderloo & Türkay, 2009, (SMF 37698); b, Nanosesarma jousseaumei (Nobili, 1905) (SMF 37689); c, Nanosesarma minutum (De Man, 1887) (SMF 30920).