Munidopsis anaramosae, De Matos-Pita, Susana S. & Ramil, Fran, 2014

De Matos-Pita, Susana S. & Ramil, Fran, 2014, Squat lobsters (Crustacea: Anomura) from Mauritanian waters (West Africa), with the description of a new species of Munidopsis, Zootaxa 3765 (5), pp. 418-434 : 428-432

Munidopsis anaramosae n. sp.

( Figs. 6–7 )

Holotype. MNCN 20.04/9118, one male 15.4 mm (Total length, rostrum included, 39.2 mm; maximum wide, 13.1 mm); MAURIT 0 811, Stn L10, off NW Banc d’Arguin ( Mauritania) 20°20´50"N, 17°53´30"W to 20°18´23"N, 17°52´03"W, 1012– 1000 m, 20 November 2008.

Etymology. This species is devoted to Dr. Ana Ramos in appreciation and recognition of her genuine enthusiasm, hard work and dedication in order to improve the knowledge of benthic fauna in African coasts.

Diagnosis. Carapace dorsally unarmed, abdomen smooth, unarmed; eye immovable, eyespine arising distally from the middle end of the cornea; no ventral spines on cheliped merus, P2–4 merus with strong spines on dorsal and ventral margins; sternite 4 anterolateral margin denticulate with a strong acute distal spine.

Description. General: Most carapace, legs, telson and endopod of uropods covered with numerous short ridges supporting bases of plumose setae ( Fig. 6 b); setation denser on legs; two spots hairless on dorsal carapace behind antennal spines and two other triangular ones lateral to cardiac ridge; ventral carapace and abdomen mostly hairless. Dorsal abdomen moderately setose not on ridges but over the exoskeleton, as occurs on dorsal anterior part of carapace.

Carapace: 1/3 longer than wide (rostrum included) with lateral margin somewhat diverging posteriorly, dorsally spineless, although with 1 low tubercle over each hepatic mesobranchial, post-cardiac and metabranchial regions can be recognized ( Fig. 6 c). Dorsal regions well delimitated by distinct grooves; anterior to cervical groove almost smooth with some scarce granulation on epigastric and hepatic regions. Cardiac region with moderately elevated transverse ridge about 1/3 as wide as carapace. Low, short and closely placed transverse ridges supporting bases of setae on upper posterolateral region. Frontal margin oblique with well-developed antennal spine. Lateral margin with the anterolateral spine small, acute and ventral to level of lateral margin; the lateral anterobranchial spine as large as antennal spine and followed backwards by 5 small conspicuous denticles ( Figs. 6 a, c, 7g). Posterior carapace ridge unarmed. Pterygostomian flap with an anterior small and acute spine; surface covered with low and short ridges.

Rostrum: Triangular, somewhat wider proximally; about 1/3 of carapace length and slightly overreaching cheliped merus in dorsal view. Distolateral margins minutely dentate. Horizontal in lateral view and with a weak dorsal longitudinal carina.

Sternum: Sternite 3 about 2 times wider than long and with rounded margins; anterior margin with shallow median notch flanked by a pair of spines followed laterally by an irregular dentition ( Fig. 7 f). Sternite 4 about 3 times as broad as preceding one, narrowing anteriorly, with anterolateral margins denticulate and preceded by a strong spine; some short setose midline ridges in the distal middle surface can be observed too ( Fig. 7 f).

Abomen: Dorsal surface unarmed. Tergites 2–4 bearing 2 transverse ridges each, the anterior narrower and raised than posterior one and reaching the pleuron ( Fig. 6 a). Tergite 6 with transverse posterior margin flanked by 2 conspicuous lobes. Distolateral and posterior margins of uropods exopod and endopod are provided with minute movable spines; uropods endopod dorsolateral surface with short ridges supporting bases of plumose setae and some scattered movable spines isolated or in groups of 2 or 3; uropods exopod with some few of these groups of movable spines on dorsolateral surface ( Fig. 7 e). Telson composed of 8 plates ( Fig. 6 c).

Eye: Ocular peduncles immovable. Cornea obliquely oval in dorsal view, non-pigmented (orange when alive). 2 eyespines, one well-developed arising from distal end of cornea, little short than eyestalk in dorsal view; the other one mesioventral and smaller, hardly visible in dorsal view.

Antennule: Basal article of antennula with 2 spines, one distodorsal and the other distolateral ( Fig. 7 a).

Antenna: Antennal peduncle short, reaching the middle of the main eye spine. Article 1 with one distolateral discrete spine and a strong distomesial spine. Article 2 with distolateral spine, mesial margin minutely serrated. Article 3 with 1 distomesial spine ( Fig. 7 c).

Maxilliped 3: Merus slighty broader than ischium, bearing 4 or 5 irregular spines on flexor margin and 2 low denticles on dorsodistal extensor margin. Ischium with one distoventral spine and 21 denticles on crista dentata. Carpus, propodus and dactylus unarmed ( Fig. 7 d).

Pereopod 1 (cheliped): Chelipeds subequal, about the same length as carapace (rostrum included), with short pilosum ridges all over dorsal surface. Ischium with distodorsal, distoventral and distomesial spines, distodorsal one followed by another blunt spine; distomesial margin serrated. Merus with 4 distal spines (dorsal, lateral, mesiodorsal and mesioventral); dorsal spine joined proximally with a longitudinal row of 5 other spines on dorsal crest; ventral surface unarmed. Carpus as long as broad, bearing 3 spines (dorsolateral, dorsal and mesiodorsal), the latter followed mesiodorsally by an oblique crest of 2 strong spines; ventral distomesial margin minutely denticulate. Palm as long as broad, spineless; fixed finger denticulate on anteroexternal margin; movable finger as long as palm; prehensile margin of the fingers spooned distally and followed proximally by a weakly crenulated carina, more notorious on fixed finger. Epipod absent.

Pereopods 2–4: P2–4 covered with short setose ridges more abundant on dorsal surface. P2 almost reaching the tip of chelipeds when extended forward. P3 and P4 diminishing in lenght and reaching middle propodus of the preceding leg. P2–4 meri relatively broad and compressed, with 7, 5 and 4 strong and acute spines respectively on dorsal margin and 4–5 spines on ventral margin ( Fig. 6 a). Each carpus with 2 dorsodistal spines: strong dorsal one followed by 3 other strong dorsal spines and the other one less strong and followed laterally by a conspicuous carina; ventral distomesial margin denticulate. Propodus less than twice length of dactylus, ventral margin ending in 3 movable spines. Dactylus ending in relatively short, strongly curved claw, flexor margin with 10 teeth decreasing in size proximally ( Fig. 7 b). Right P5 lost. Epipods absent.

Color. Whitish exoskeleton with orange cornea when alive; setae often covered with mud particles giving a dark appearance to the whole animal. Whitish in alcohol.

Distribution. Only known from the type locality: off northwestern Banc d’Arguin, Mauritania, 1006–1012 m deep.

Remarks. Chace (1942), aiming to compare and identify the species in the speciose genus Munidopsis , subdivided it into artificial groups, bringing together related species using some relevant morphological features. In this way M. spinoculata (A. Milne Edwards, 1880) and M. hendersoniana Faxon, 1893 were grouped by “the huge terminal spine of the eyestalk practically passes through the cornea”. Baba (1988) described two new species, M. bispinoculata and M. similior , that he included in this group, and he added three more species: M. pilosa Henderson, 1885 , M. ramahtaylorae Pequegnat and Pequegnat, 1971 and M. subspinoculata Pequegnat and Pequegnat, 1971 . Other species that can be referred to this group too are: M. victoriae Baba & Poore, 2002 , M. rotundior, Baba, 2005 and now M. anaramosae n. sp., raising to ten the number of Munidopsis species provided with a well-developed eyespine arising from the distal end of the cornea.

Munidopsis victoriae (type locality off Portland, Victoria, southeastern Australia, 990 m), M. hendersoniana (see Baba 2005: 152; Gulf of Panama, Pacific Ocean, 915–1897 m) and M. pilosa (Indian and western Pacific Oceans, 732–1600 m) are provided with spines on the dorsal and ventral margins of the P2–4 merus; nevertheless in M. hendersoniana and M. pilosa the cornea become divided into mesial and lateral lobes by ocular peduncle but not in our species. Munidopsis victoriae shows the cornea undivided like in M. anaramosae , but cheliped merus bears 2–4 ventral spines while is unarmed in M. anaramosae . Moreover, these three species show a different morphology and sculpture on sternites 3 and 4.

Munidopsis ramahtaylorae Pequegnat & Pequegnat, 1971 , M. spinoculata (A. Milne Edwards, 1880) and M. subspinoculata Pequegnat & Pequegnat, 1971 were recorded from the Atlantic Ocean but none of them have spines on the dorsal and ventral margins of the P2–4 carpus.

Munidopsis bispinoculata Baba, 1988 , M. rotundior Baba, 2005 and M. similior Baba, 1988 , known from the Indian and Pacific Oceans, have the P2–4 merus spinose but only on the dorsal margin. The absence of spines on the ventral margins of the P2–4 merus in these three species separates them from M. anaramosae n. sp in which the P2–4 meri are provided with spines on the dorsal and ventral margins. None of the last three species have been recorded from Atlantic Ocean. Therefore, M. anaramosae n. sp. is the first species of the genus, having the eyespine arising from distal end of the cornea and with the dorsal and ventral margins of the P2–4 merus spinose, recorded in the Atlantic Ocean.

Figures

FIGURE 6. Munidopsis anaramosae n. sp., male, holotype MNCN 20.04 / 9118, MAURIT 0 811 Stn L 10. Entire animal a) lateral view b) dorsal view c) dorsal view, P 1 – 4 removed. Scale bar a, c, 5 mm; a, c: all setae omitted.

FIGURE 7. Munidopsis anaramosae n. sp., male, holotype MNCN 20.04 / 9118, MAURIT 0 811 Stn L 10 a) right antennula, ventral view b) left P 2 c) right antenna, ventral view d) right mxp 3, ventral view e) right uropod, dorsal view f) anterior sternum g) anterior carapace. Scale bar: a, c, d – f, 1 mm; b and g, 5 mm; all setae omitted.