Menaethiops abumusa, Naderloo, Reza, 2015

Naderloo, Reza, 2015, A new species of decorator crabs, genus Menaethiops Alcock, 1895 (Crustacea: Decapoda: Brachyura: Majoidea: Epialthidae), from Abu-Musa Island, Persian Gulf, Iran, Zootaxa 3925 (3), pp. 431-437 : 432-437

Menaethiops abumusa n. sp.

( Figs. 1 , 2 , 3 a–e, 4a–d)

Material examined. Holotype: male (CL = 13.60, CB = 9.72 mm) ( ZUTC 5319), Park-Ghadir, Abu-Musa Island, Persian Gulf, 25º 53'N, 55º 01'E, rocky/rubble intertidal, coll. R. Naderloo & H. Rahimian, 0 1 May 2014.

Paratypes: 10 males, 12 females (1 ovigerous), 1 juv. ( ZUTC 5320), locality data same as holotype; 1 male (CL = 10.50, CB = 7.22 mm) ( ZUTC 5324), Qeshm Island, Persian Gulf, rocky/rubble intertidal, coll. R. Naderloo; 1 male, 2 females, ( ZUTC 5321), Jod village, Sistan-Baluchestan, Gulf of Oman, 25º 17'N, 59º 30'E, rocky/rubble, 0 7 February 2009, coll. H. Salehi et al.

Comparative material. Menaethiops nodulosus ( Nobili, 1906) : 1 male (CL = 5.50, CB = 3.09 mm) ( SMF), Juraid Island, Saudi Arabia, Persian Gulf, under dead corals, 5 m depth, 27°12'N 49°57'E, coll. M. Apel, 26 February1993; 1 ovigerous female (CL = 4.50, CB = 3.20 mm), ( SMF), 1 km South of Khor Fakkan, UAE, Gulf of Oman, 25° 20'N 56° 22'E, rocky, under sea stars, 10–20 m depth, 0 1 July 1995, coll. M. Apel; 1 ovigerous female (CL = 1.00, CB = 8.60 mm), ( ZMUC CRU 868), S.O.S. of Bustani, Iran, Persian Gulf, Danish Expedition DSII, 27° 05'N 53° 02'E, algae and sand, 4–5 m depth, 0 6 April1937, coll. G. Thorson; 1 male (CL = 9.40, CB = 6. 30 mm), ovigerous female (CL = 9.00, CB = 6. 40 mm), ( ZMUC CRU 861), northeast head of Kish Island, Iran, Persian Gulf, Danish Expedition DSII St. 56, 26° 32'N, 54° 03'E, 3–4 m depth, 0 9 April 1937, coll. G. Thorson; 3 males, 7 females (4 ovig.), ( ZUTC 5322), Jod Village, Sistan-Baluchestan, Iran, Gulf of Oman, 25º 17'N, 59º 30'E, rocky/ rubble, 0 7 February 2009, coll. H. Salehi et al.

Menaethiops gadaniensis Kazmi & Tirmizi, 1999: 15 males, 12 females (ovig.), 1 juv. (ZUTC 5323), Jod Village, Sistan-Baluchestan, Iran, Gulf of Oman, 25º 17'N, 59º 30'E, rocky/ rubble, 0 7 February 2009, coll. H. Salehi et al.

Description. Carapace broad pyriform ( Figs. 1 , 3 a), about 1.4 times as long as wide (including rostral spines); posterior surface uneven, carapace region well defined; hepatic region distinctly round, elevated, separated from branchial margin with deep furrow, large apically rounded tubercle on anterior margin of hepatic region, small tubercle on upper surface; two small elevations between hepatic and gastric regions; gastric region slightly elevated, with two small granules; branchial margin distinctly arched, with small tubercle on anterior part, large pyramid-shape tubercle on dorsal branchial region; hepatic region distinctly elevated, round, slightly uneven, without tubercle; intestinal region with elevation transversely extended.

Rostrum about one-third of postrostral carapace length, slightly extended beyond fourth antennal segment, with two spines, spines wide in proximal part, tapering distally, tightly attached to each other in half proximal, slightly diverging distally, spines slightly curved downward in half distal, hooked setae on half proximal.

Orbit with anterior, posterior angles not produced, eyestalk relatively long, eyes visible from dorsal view. Basal antennal segment elongated ( Fig. 3 c), smooth, anterolateral margin produced as large blunt tubercle, inner margin with small denticle-shape process in half distal, second antennal segment about 1.2 times as long as third segment. Buccal cavern with anterolateral margin distinctly elevated. Pterygostomian region usually with five tubercles, becoming larger distally ( Fig. 3 b). Third maxillipeds ( Fig. 3 e) with ischium distinctly longer than merus, inner margin with denticles; merus quadrate shaped, anterior margin straight, serrated, surface distinctly concave.

Male chelipeds relatively large ( Fig. 2 ), as long as carapace (including rostral spines), or slightly longer; merus of male chelipeds ( Fig. 4 b) about three times as long as wide, lower surface with longitudinal line of small granules, line curving distally; lateral surface with round granules in longitudinal line; upper margin with teeth like tubercles, median one largest; carpus with granules on upper surface; palm ( Figs. 2 , 3 d) distinctly large, about twice as long as high, outer, inner surface, upper, lower margins smooth, without tubercles or denticles; fingers short, movable finger half as long as palm, longer than immovable finger, both fingers with blunt teeth on half distal, long tooth on proximal part of movable finger, wide distinct gap proximally between fingers.

Walking legs long, first one longest, becoming smaller from first to last one, posterior surface of ischium, merus, carpus and first half proximal of propodus granulate, merus of first leg particularly long, about eight times longer than broad, merus smaller from first to last one, merus of least one about three times longer than broad; propodus of last leg nearly as long as merus; dactylus long spine-shape, curved, posterior margin with spines along two-third proximal.

Male abdomen ( Fig. 4 c) with somites freely movable, densely tuberculated as thoracic sternites, third somite broadest, getting narrower distally, fourth somite sharply converging proximally, straight in half distal, fifth somite longest, converging medially, sixth somite diverging in two-third distal, telson distinctly longer than sixth somite, rounded apically.

Male G1 ( Fig. 4 d) straight, slightly narrowing distally, apically with two triangular lobes, widely separated, inner lobe longer and narrower than lateral one.

Etymology. The species name was derived from the type locality, Abu-Musa Island in the Iranian territory of the Persian Gulf.

Remarks. Currently, 15 species of the genus Menaethiops are known of which just one species, Menaethiops nodulosus ( Nobili, 1906) (originally described as Parahoplophrys nodulosa ), was described and recorded from the Persian Gulf ( Nobili 1906). Menaethiops nodulosus is different from the new species by having widely divergent rostral spines, distinctly produced orbital eaves, and morphology of chelipeds ( Fig. 5 b). Menaethiops abumusa n. sp. is rather very closely related to M. bicornis Alcock, 1895 , and M. gadaniensis Kazmi & Tirmizi, 1999 ( Fig. 5a ) with respect to the long and relatively contiguous rostral spines. The rostral spines of M. abumusa n. sp. are slightly divergent distally, while in both of the other congeners the rostral spines are closely attached to each other along their entire length. Menaethiops bicornis and M. gadaniensis have two spines on the bulged hepatic region, but there is a distinct tubercle on the hepatic region in the new species. The basal antennal segment in M. bicornis is distally two-lobed, with the outer lobe being distinctly shorter than the inner lobe and the lateral margin of the basal antennal segment nearly straight, while in related congeners, the anterolateral lobe of the basal antennal segment is tooth-shaped and larger than the inner lobe, and the lateral margin of the segment is sinuous with two concavities (see Tirmizi & Kazmi 1986: 168, fig. 52b; Kazmi & Tirmizi 1999: 371, fig. 1B; Naderloo & Türkay 2012). Menaethiops gadaniensis has strongly produced orbital eaves and longer rostral spines, whereas orbital eaves of M. abumusa n. sp. are not produced and rostral spines are shorter in comparison to the postrostral length of the carapace. Furthermore, regarding the morphology of the G1, M. gadaniensis is distinct from its congeners by having the apical inner lobe markedly hook-shaped (see Kazmi & Tirmizi 1999: 371, fig. 1G, G', G'').

Distribution. So far only known from Abu-Musa Island in the Persian Gulf, and Iranian coast of the Gulf of Oman in the intertidal rocky/rubble habitat.

Figures

FIGURE 1. Menaethiops abumusa n. sp. Holotype (ZUTC 5319) CL = 13.60, CB = 9.72 mm, from dorsal view.

FIGURE 2. Menaethiops abumusa n. sp. Holotype (ZUTC 5319), right cheliped from outer view. Scale bar: 2 mm.

FIGURE 3. Menaethiops abumusa n. sp. male paratype (ZUTC 5324), CL = 10.50, CB = 7.22 mm: a, posterior surface of carapace; b, orbital and pterygostomian region, lateral view; c, basal antennal segment; d, palm of the right cheliped, outer surface; f, third maxilliped, outer surface.

FIGURE 4. Menaethiops abumusa n. sp. male paratype (ZUTC 5324), CL = 10.50, CB = 7.22 mm: a, last walking leg, posterior surface; b, merus of male chelipeds, lateral surface; c, male abdomen; d, G 1 of male, lateral surface.

FIGURE 5. a, Menaethiops gadaniensis Kazmi & Tirmizi, 1999 (ZUTC 5323), CL = 12.10, CB = 8.40 mm; b, Menaethiops nodulosus (Nobili, 1906) (ZUTC 5322), CL = 11.02, CB = 7.20 mm, from dorsal view.