Nanosesarma jousseaumei ( Nobili, 1906 )

Naderloo, Reza & Türkay, Michael, 2009, A new species of the genus Nanosesarma (Crustacea: Decapoda: Brachyura: Sesarmidae), and redescription of Nanosesarma jousseaumei (Nobili, 1906), including new records from the Persian Gulf, Journal of Natural History 43 (47 - 48), pp. 2911-2923 : 2918-2923

Nanosesarma jousseaumei ( Nobili, 1906)

( Figure 1C, D , 4A– F )

Sesarma (Sesarma) jousseaumei Nobili, 1905, p. 411 ; Nobili, 1906, p. 323, pl. 8, figure 9. Sesarma (Sesarma) jousseaumei Lauri, 1915, p. 416 ; Guinot, 1967, p. 283. Nanosesarma jousseaumei Holthuis, 1977, p. 172 –174; Ng et al., 2008, p. 221 –224.

Type locality

Gulf of Aden ( Djibouti and Obock).

Material examined

Lectotype. 13 ( MNHN B16696) (Cl = 4.8, Cb = 5.3), Dr. Jousseaume, Mer Rouge, 1897.

Paralectotype. 1♀ ( MNHN B16696) (Cl = 4.0, Cb = 4.5), Dr. Jousseaume, Mer Rouge, 1897 .

Material from the Persian Gulf, Iran. 13 ( ZUTC Brach 1161), Hormuzgan, Parsian ( Gavbandi ), 35 km E. to Gavbandi , Morghdan village , 27°06′N, 53°03′E, sandy-rocky, 12.05.2006, R. Naderloo; 23, 5♀ (3 ovig.) ( ZUTC Brach 1162) , Qeshm Island, S. coast, 10 km E. of Salakh , 26°40′N, 55°44′E, rocky bed, 11.05.2008, R. Naderloo and A. Kazemi; 1♀ (SMF-34380) , Qeshm Island, S. coast, 26°35′N, 55°28′E, sandy-rocky, 07.05.2008, R. Naderloo and A. Kazemi; 13, 2♀ ( ZUTC Brach 1163) , Qeshm Island, S. coast, 26° 51′N, 56° 08′E, sandy-cobble, 10.01.2008, M. Türkay and R. Naderloo .

Further material. 13, 3♀ (SMF-25147), Djibouti, City of Djibouti, Plage de Triton, intertidal zone, under stones, 18.03.1987, leg. Allspach, Fischer and Türkay; 13 ( MNHN B16193) Madagascar, Nosy Bé, intertidal, A. Crosnier col. et det. as Nanosesarma cf. minutum ; 13, 1♀ ( MNHN B16195), Madagascar, Nosy Bé, in intertidal oyster bank, A. Crosnier col et det. as Sesarma (cf) minutum De Man ; 2♀ ( MNHN B16196), Madagascar, Nosy Bé, intertidal, sand stone beds, A. Crosnier col et det. as Sesarma cf. minutum De Man ; 23, 1♀ ( MNHN B16194), Madagascar, Tuléar, intertidal, Plante collection, A. Crosnier det. as Sesarma cf. minutum De Man ; 43, 2♀ (1 ovig.) ( NHM 1973: 89 CR08/21 T), Tansania, Dar es Salam area, rocky cliff, leg. R. G. Hartnoll, April 1972, identified as Nanosesarma minutum (De Man) .

Description

Carapace ( Figure 1C,D , 4A ) square, slightly broader than long ( CB /CL about 1.1), nearly uneven, smooth, covered with short plumose setae, long setae sparsely set among shorter ones, regions well defined, frontal region with two lobes, a shallow sulcus separating them, extending backward to gastric region, straight depression separating gastric region from cardiac, two very short, oblique, depressed lines centrally in front of this straight depression, cardiac region with two small elevations, separated from intestinal region by a shallow depression, a prominent depression behind orbits, one weakly granulated oblique ridge on posterior surface of carapace, extending from lateral margin towards posterior edge, stopping at small elevation near posterolateral edge.

Frontal region relatively sharp and deflexed, frontal ridge about half as broad as carapace, weakly serrated, two-lobed, slightly protruded, not overreaching inner angle of orbit, separated by a wide semicircular notch.

Orbit about one fourth carapace breadth, posterior margin sinuous, finely serrated, exorbital angle widely triangular, infraorbital margin straight, completely denticulate, denticles becoming nearly large in middle part, inner margin subrectangular rather than triangular.

Basal antennal segment ( Figure 4B ) long, reaching to base of flagellum. Third maxilliped morphology identical to that of N. sarii .

Chelipeds distinctly unequal, ischium denticulate on anterior margin, merus relatively large, very small tubercles sparse on outer surface, inner surface smooth, posterior, anterior and lower margins granulated, anterodistal margin with a rectangular process, small tubercles sparse on posterior surface of carpus, outer margin with slightly more numerous tubercles, inner angle triangular, minutely serrated. Palm ( Figure 4C ) relatively large, outer surface fully covered with dense setae, three rows of tubercles underneath the setae, lower one with small tubercles, extending from proximal part to basal third length of lower finger, middle one shortest, oblique, with relatively large tubercles, upper row of granules short, nearly parallel to median one. Lower margin with an elevation on proximal half of lower finger, upper margin with sparse tubercles, inner surface smooth on lower part, some tubercles present on upper part. Fingers slightly narrow, shorter than palm, with a large gap in proximal half, getting narrower distally, movable finger straight, small granules proximally on upper surface, a large distinct tubercle proximally on outer surface, cutting edge of movable finger with six to seven low tubercles on distal half, distal one large, cutting edge of immovable finger with a large prominent tubercle in middle part, two low ones proximally next to the large one, tips of fingers spoon-shaped. Chelipeds of female nearly equal, small, narrow, movable finger without proximal tubercles on outer face, cutting edge of fingers with distinct teeth on proximal part.

Walking legs medium-sized, first and second ones longest, anterior margin of merus weakly serrated, without subdistal spine, posterior margin ( Figure 4D ) with some distinct tooth-shaped granules, two large ones medially, posterodistal margin with spiniform teeth, proximal one largest. Carpus with a longitudinal line of very small tubercles on anterior and posterior margins, last leg ( Figure 4D ) without this line on posterior surface of carpus. Propodus length about twice width or slightly longer, about 1.5 times dactylus length, smooth, with two groups of three small spines on posterodistal end. Dactylus ending in a large spine, six spines, in two rows along posterior margin, getting larger distally, all segments of walking legs, except dactylus, densely covered with short plumose setae, long bristles between them.

Male abdomen ( Figure 4E ) with sixth segment about 3.5 times as broad as long, lateral margin gently converging distally, telson not elongate, very slightly longer than broad, apical part rounded.

G1 ( Figure 4F ) straight, with a long corneous distal part, gently bending outward, covered with long bristles, posterior surface concave, sperm channel nearly straight, distal opening in posterior apical part. Some plumose setae along lateral margin. Genital opening of female exactly same as that of N. sarii n. sp.

Size

This species is relatively small sized compared to the other species of the genus Nanosesarma . The male lectotype measures CL = 4.8, CB = 5.3, female paralectotype CL = 4, CB = 4.5.

Colour

Fresh specimens from the Persian Gulf are generally light 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 parts.

Habitat

Nobili (1906) did not report the habitat of the type material. The material deposited in the Senckenberg Museum was collected in the intertidal zone, living under stones as the specimens from the Persian Gulf.

Distribution

Madagascar, Dar es Salam, Gulf of Aden ( Djibouti and Obock) and Persian Gulf.

Remarks

Serène and Soh (1970) synonymized N. jousseaumei ( Nobili, 1906) with N. minutum, De Man, 1887 . Subsequently, Holthuis (1977) redescribed this species based on one small female from Ethiopia, and stated that this species is closer to N. gordoni (Shen, 1935) , rather than to N. minutum ; he did not doubt the validity of N. gordoni . Nanosesarma gordoni (Shen, 1935) is, however, in all respects identical with N. minutum . So far three studies have considered N. gordoni to be a junior synonym of N. minutum ( Serène and Soh, 1970; Davie 1998; Ng et al. 2008). Some specimens of N. gordoni [13, 2♀ (SMF-30920) Japan, Shikimi, M. Matsuo] and N. minutum (103, 8♀ ( BMNH 1961.11.13.130-140) Japan, Natake-Sima, I. Gordon and K. Sakai) were available for us to compare them with each other and with other species of this genus. We could not find any difference between N. minutum and N. gordoni , in particular in comparisons of the male cheliped, walking legs and the male abdomen. The original description and drawings provided by Shen (1935) are also insufficient to separate these two species. Therefore, we support the synonymy of both species. Further, Holthuis (1977) mentioned that specimens of Nanosesarma cf. minutum (De Man) which Crosnier (1965) had reported from Madagascar, are probably identical with N. jousseaumei based upon the description and illustration given by Crosnier (1986: 70–74, Figures 109–115). The first author had an opportunity to examine Crosnier’s specimens from Madagascar deposited in the MNHN, and would like to support Holthuis’s statement, however description and drawings (especially that of the cheliped) of Crosnier’s specimens from Madagascar are slightly different from here examined specimens of N. jousseaumei (see Figure 4 ).

Ng et al. (2008) already listed this species as a valid species in their catalogue of Brachyura. We are now confirming the validity of N. jousseaumei , which is similar in most respects to N. minutum . These two species are easily distinguishable as follows: The second epibranchial tooth of N. jousseaumei is blunt, that of the N. minutum remarkably triangular and pointed; the shape of the male palm is distinctly wider in N. jousseaumei . The large gap between the proximal part of the fingers of the male in N. jousseaumei and the presence of a large tubercle proximally on the outer surface of movable finger of the male of this species also makes it different from N. minutum .

Furthermore, the size of the walking legs, in particular the size of the propodus, which is about one and half times as long as broad, and the granulation of the posterior margin of the merus of the walking legs with some blunt and comparably large teeth in the middle part, allows N. jousseaumei to be separated from all other congeners. In the remaining species, the propodus is usually longer, about twice as long as wide, and the posterior margin of the merus of the walking legs is either slightly serrate or possesses very small denticles.

Conclusions

Until now, only one species of the genus Nanosesarma , N. minutum De Man , had been recorded from the Arabian side of the Persian Gulf ( Jones 1986; Apel 2001), which in reality belongs to the new species N. sarii n. sp. With the new records of N. jousseaumei from our material, the number of species of Nanosesarma in the Persian Gulf now rises to two. Both, N. sarii and N. jousseaumei have a western Indian Ocean distribution including the Persian Gulf and Pakistan. Nanosesarma jousseaumei has been found in the Gulf of Aden and off the east coast of Africa. It is possible that N. sarii will be found further westwards once more studies are done of small sesarmids in this region.

Acknowledgments

We would like to thank Dr Peter Davie, Queensland Museum for his valuable comments on the species and manuscript, Dr Alireza Sari, University of Tehran for his support towards the first author and providing opportunity for sampling. Our thanks also are due to Mr A. Kazemi, University of Tehran, for his valuable help during our field work. This study was supported by University of Tehran and through a grant of the German Academic Exchange Service ( DAAD), Bonn, Germany, which we gratefully acknowledge.

Figures

Figure 1. (A) Nanosesarma sarii n. sp., holotype (SMF-34376, CL = 6.12, CB = 7.15 mm), posterior view; (B) same specimen, ventral view; (C) Nanosesarma jousseaumei (Nobili, 1906), Lectotype (MNHN B16696, CL = 4.8, CB = 5.3 mm), posterior view; (D) N. jousseaumei (Nobili, 1906), (ZUTC Brach1161, CL = 4.12, Cb = 4.77 mm), posterior view.

Figure 4. Nanosesarma jousseaumei (Nobili, 1906), lectotype (MNHN B16696): (A) carapace; (B) basal segments of first and second antenna; (C) palm of the right cheliped (outer surface); (D) left last walking leg; (E) abdomen of male; (F) G1 (ventral face). Scale bars = 1 mm.