Nanosesarma sarii, Naderloo & Türkay, 2009

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 : 2912-2918

Nanosesarma sarii n. sp.

( Figures 1A, B , 2A–F , 3A–I ) Nanosesarma (Nanosesarma) minutum Tirmizi and Ghani, 1996, p. 159 , Figure 61 A–D. [not Sesarma minutum De Man, 1887 ] Nanosesarma minutum Jones, 1986, p. 160 , pl. 46. [not Sesarma minutum De Man, 1887 ]

Material examined

Holotype. 13 (SMF-34376) (CL = 6.12, CB = 7.15), Persian Gulf , Iran, Bandar-Abbas, behind Airport, 27° 47′N, 56° 24′E, muddy bank of tidal water channel, under stone, leg. M. Türkay and R. Naderloo, 07.01.2008.

Paratypes. Persian Gulf , Iran : 233, 11♀ ( ZUTC Brach 1151), the same locality as holotype; 43 , 8♀ (4 ovig.) ( ZUTC Brach 1152), Khuzestan, Bandar-Mahshahr , fisheries jetty, 30°28′N, 49°11′E, muddy substrate with planted mangroves, 16.04.2006, R. Naderloo and A. Kazemi; 93 , 12♀ ( ZUTC Brach 1153), Hormuzgan, Mahtabi , 26°46′N, 55°20′E, oyster bank and muddy-sand, 25.04.2008, R. Naderloo; 143 , 4♀ (2 ovig.) ( ZUTC Brach, 1154), Qeshm Island , Basaeedu, 26°36′N, 55°16′E, rocky bed, 07.05.2008, R. Naderloo and A. Kazemi; 33 ( ZUTC Brach 1155), Hormuzgan, Bandar-Khamir , 26°28′N, 55°35′E, muddy-sandy shore, 07.06.2006, R. Naderloo and A. Kazemi; 43 , 4♀ (3 ovig.) ( ZUTC Brach 1156), Bushehr, Delvar , Park-Saheli , 28°54′N, 51°89′E, muddy substrate on creek bank, 11.04.2006, R. Naderloo and A. Kazemi; 23 , 2♀ (ovig.) ( ZUTC Brach 1157), Bushehr, Bandar-Dayyer , rocky with dead coral (partly covered with algae), 27°14′N, 51°16′E, 12.04.2006, R. Naderloo and A. Kazemi; 13 ( ZUTC Brach 1158), Bushehr , Bandargah , 28°49′N, 50°54′E, sandy-rocky, 13.04.2006, R. Naderloo and A. Kazemi; 133 , 11♀ (7 ovig.) (SMF- 34377) Qeshm Island , Zeyton (olive) park, 27°11′N, 56°24′E, sandy-rocky with dead corals, 08.01.2008, M. Türkay and R. Naderloo; 103 , 14♀ (SMF-34378), Qeshm Island , 2 km east of desalination center, 26°56′N, 55°47′E, 15.01.2008. M. Türkay and R. Naderloo; 263 , 17♀ (ovig.) ( ZUTC Brach 1158), Khuzestan, Bandar-Emam , Park-Saheli , 30° 28′N, 49° 04′E, muddy bank of creek, artificial rocky structure, 21.05.2008, R. Naderloo and H. Salehi. Gulf of Oman : 13, 1♀ (ovig.) (SMF-34379), Chabahar, behind Shahid Beheshti Jetty , 30° 10′N, 50° 05′E, muddy-sand with dead corals, 22.10.2006, A. S Sari and R. Naderloo .

Other material. 1♀ ( NHM 1985 :512 CR08/21), previously identified as Nanosesarma minutum (De Man, 1887) , Manora Island , West Wharf, Karachi, Pakistan, S. S. Hashmi

Description

Carapace square ( Figures 1A , 2A ), slightly broader than long (CB/CL about 1.13–1.17), greatest breadth across second anterolateral teeth, evenly convex, sparsely covered with short and thin plumose setae. Front (including the inner lobe of orbit) about 0.6 times maximum CB, slightly less than twice breadth of the posterior edge of carapace, sinuous, with two wide lobes, lobes convex and moderately produced, slightly beyond inner supraorbital angle, separated by a semicircular median notch, frontal edge serrated, beaded upwards, frontal region gently deflexed, a broad shallow sulcus running posteriorly separating two distinct frontal ridges. Inner orbital angle nearly rounded, upper margin sinuous, finely serrated like frontal margin, without fissure, infraorbital margin straight, prominently serrated, completely separated from outer triangular part, a raised line on inferior surface of outer angle, completely serrated with long setae.

Anterolateral margin with two teeth (including exorbital angle), first one widely triangular, second one triangular, small, with pointed tip, separated from former by a shallow V-shaped notch, lateral border behind second tooth slightly convergent.

Carapace regions ( Figure 2A ) well defined, gastric region surrounded by a deep groove, cardiac region with a shallow groove, a small depression behind supraorbital margin, very fine granules on upper surface of carapace, always two or more granules in a line, two oblique granulated ridges along lateral part, first one shortly behind second anterolateral tooth, extending from lateral margin towards central region of carapace, second one near end of lateral margin, parallel to first, longer, ending at posterolateral edge, two further less-prominent, short ridges present, one running from second lateral tooth, subparallel to first prominent ridge, other behind first prominent one, nearly parallel to that.

Basal antennal segment long ( Figure 2B ), reaching to about middle of second segment, flagellum of antennae short, but reaching to cornea of eye. Proximal half of eye-stalk covered with granules similar to those on carapace.

Third maxillipeds ( Figure 2C ) covering buccal cavity, with a large inner gap between them, merus with a longitudinal furrow along outer surface, internal and external margins crenulated, long setae along internal margin, internal margin of ischium crenulated, with long setae, exopod relatively slender.

Chelipeds subequal, inner margin of ischium distally denticulated, a long stiff medial bristle on inner margin. Inner margin of merus proximally crenulated, inner surface smooth, with a longitudinal line of short setae, and some scattered short setae, outer surface with transverse lines of small granules same as those on carapace. Carpus with prominent transverse lines of granules on outer surface, inner smooth surface with a line of long stiff setae. Manus ( Figure 2D ) slightly swollen, outer surface with a large patch of dense setae, covering whole manus above lower row of granules, extending to proximal part of fingers, three rows of granules thereon, concealed by a tuft of setae, lower one long, regularly granulated, extending from proximal part to middle of immovable finger, middle one short, with irregular large granules, subparallel to lower one, upper one short, with irregular granules, curving upwards, surfaces above these granular rows granulated, below long line smooth, a crenulated longitudinal line ( Figure 2E ) along upper margin, inner surface of manus with granules on proximal part same as those on carapace.

Movable finger ( Figure 2E ) as long as manus, upper surface, except apical part, completely tuberculated, with densely set small tubercles on proximal part, six relatively large granules proximally on outer surface, proximal ones always larger, all concealed by tufts of setae, cutting edge with small teeth of various sizes. Immovable finger short, smooth, cutting edge with several small teeth, a large prominent one medially, brown apical part of fingers spoon-shaped.

Chelipeds of female ( Figure 2F ) small, slightly slender, manus with a patch of setae as in males, with same granulation pattern under tufts of setae as in male, movable finger smooth, with granulation on the proximal part of upper surface.

Walking legs ( Figure 3A–D ) medium-sized, second and third longer than two others, which are of same size, anterior margin of merus weakly crenulated, with a pointed subdistal tooth, posterior margin crenulated, posterodistal lobe denticulate, first denticle large, in first and second legs especially prominent and spiniform, posterior surface of merus with granules similar to those on carapace. Carpus of walking legs 1, 2, and 3 with two distinct carinae on posterior surface and one on anterior surface, carpus of last walking leg without any carina on posterior face. Propodus with an oblique carina on posterior face, stiff long setae along propodus, mainly in two rows on anterior and posterior margins, small brown setae on anterior margin of propodus of first three legs, setae of first one dense, prominent, two groups of three to five spines on distal end of posterior margin, median one prominently large. Dactylus distinctly more than half as long as propodus, with 8–10 spines, in two rows, on posterior margin, 2–3 spines on anterior margin of last walking leg, last walking leg of female without any spine on anterior margin.

Male abdomen ( Figure 3E ) elongate, triangular, smooth, sixth segment slightly more than twice as broad as long, with converging lateral margins, telson markedly elongate, about 1.6 times as long as broad.

Female abdomen ( Figure 3F ) large, completely round, length of sixth segment more than others, telson small, remarkably inserted into sixth segment, long setae on margins of all segments, margin of telson with short setae.

G1 ( Figure 3G ) medium-sized, nearly straight, corneous distal part directed outwards, with long, stiff setae around it, some setae along lateral margin, sperm channel curved along proximal part, with terminal opening on lateral side ( Figure 3H ).

Genital opening of female ( Figure 3I ) with a nearly long oval operculum on inner side, a small semicircular process on outer side.

Size

Like other members of this genus, specimens of this species are small but seem to be larger than other congeners. Mean size CL = 4.5, CB = 5.5. Maximum sizes of largest male CB = 8.77, CB = 9.95, largest female CB = 8.24, CB = 9.21, smallest ovigerous female CL = 3.1, CB = 3.6.

Colour

Living specimens with carapace relatively light brown, darker brown in anterior part. Chelipeds, walking legs, and abdomen lighter than carapace, sometimes with brown banding on walking legs. Dark brown setae on the outer surface of manus of chelipeds and upper margin of propodus of walking legs, giving a dark appearance to these parts.

Habitat

This species lives in different habitats with a variety of sediment grain-sizes. On rocky shores and in coral beds it is found hiding under small stones and corals. In mangrove forests it lives among the roots of mangrove trees, under decaying wood, and under large dead shells. In oyster banks it is found amongst oyster shells, and also occurs in sheltered sandy-muddy shores burrowing in the sediments.

Distribution

Coasts of the Persian Gulf, Gulf of Oman and Pakistan.

Etymology

This species named after Dr Alireza Sari, Associate Professor in the University of Tehran, who was the supervisor of the MSc thesis of the first author and encouraged him to study brachyuran crabs of the Persian Gulf.

Remarks

Nanosesarma sarii n. sp. differs distinctly from all other species of the genus by the following two features. Firstly, the granulation pattern on the cheliped is quite different. There is a longitudinal low of small granules on the upper surface of the cheliped palm, the movable finger is relatively more granulated, being nearly completely covered with small tubercles on the upper surface and with six prominent granules present proximally on the outer surface of the movable fingers. Secondly, the male abdomen is prominently elongate, more so than in almost all other congeners, with the sixth segment and telson differing markedly in size and shape. The elongation of the abdomen is mainly due to the long sixth segment and telson. The new species is closest to N. minutum De Man, 1887 and N. jousseaumei in particular, in having the carapace wider than long. However, it is easily distinguishable from its closest relatives in having the two features listed previously. While it resembles N. minutum with regard to the size of the basal antennal segment, morphology of the G1 and the presence of an acute epibranchial tooth, N. sarii n. sp. is not nearly as setose as N. minutum . Large specimens of this new species have very sparse setae on the carapace and appendages; the carapace sometimes looks nearly glabrous. The crabs figured by Jones (1986: 160, pl. 46) from the Kuwait coast of the Persian Gulf and by Tirmizi and Ghani (1996: 159, Figure 61 A–D) from Pakistan waters under the name N. minutum are most probably identical with this new species. Furthermore, one female specimen of Nanosesarma from Karachi, Pakistan deposited in NHML (under the name of N. minutum ) was also identified as N. sarii .

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 2. Nanosesarma sarii n. sp., holotype (SMF-34376). (A) carapace; (B) basal segments of first and second antenna; (C) right third maxilliped; (D) palm of left cheliped (outer face); (E) upper surface of palm and finger of left cheliped; (F) N. sarii n. sp., female paratype (ZUTC Brach1151), palm of left cheliped. Scale bars = 1 mm.

Figure 3. Nanosesarma sarii n. sp. Holotype (SMF-34376) (A–E, G–H) and female paratype (ZUTC Brach1151) (F, I). (A) first walking leg (left); (B second walking leg (left); (C) third walking leg (left); (D) last walking leg (left); (E) abdomen of male; (F) abdomen of female; (G) G1, right (ventral face); (H) G1, right (posterior face); (I) genital opening of female. Scale bars = 1 mm.