Atarbolana beirutensis, Castelló, 2017

Castelló, José, 2017, New and little-known species of isopods (Crustacea, Isopoda) from the eastern Mediterranean, Zootaxa 4311 (2), pp. 151-182 : 159-163

Atarbolana beirutensis sp. nov.

( Figs 6–8 )

Material examined. Holotype: ovigerous female, 4.5 mm, sample 5M15, station 11, Raoucheh, Beirut, Lebanon, 33°53'18”N, 35°28'01”E, 0–1 m, cave, G. Bitar & H. Zibrowius coll., 17 Sept. 2002 ( MZB2016-3479, 20 slides).

Paratypes: damaged female without posterior section of body, sample 5M15, same locality as holotype ( MZB2016-3480, 15 slides); juvenile, 2 mm, sample 5M16, same locality as holotype ( MZB2016-3481 ); depth between 0 and 3 m, G. Bitar & H. Zibrowius coll., 17 Sept. 2002 .

Diagnosis. Body 2.4 times longer than wide. Posterior margin of cephalon with groove on each side. Frontal lamina pentagonal, elongated, with triangulate anterior and concave lateral margins. Pereonites 4–7 with transverse grooves. Apex of pleotelson truncated, with 10 robust setae. Uropodal exopod like an elongated spoon, with concave section.

Description of holotype [MZB2016-3479]. Body 2.4 times longer than wide. Cephalon with apex of rostral process overlapped by frontal lamina; posterior margin of cephalon with groove on each side. Frontal lamina pentagonal, with triangulate anterior and concave lateral margins. Pereonite 1 slightly longer than remaining pereonites, equal in length; pereonite 1 with lateral simple suture; coxae 2–3 with longitudinal suture almost parallel to the margin; coxae 3–7 with oblique suture. Few setae on margins of pereonites 3–7; surface of body smooth, without setae. Transverse dorsal groove on pereonites 4–7. Pleonites 2–5 visible from above, last three almost equal in length, without denticles. Pleotelson narrowed, concave in distal half, and truncated distally; apex with 10 robust setae and 4 long simple setae, two of them in the middle; lateral margins of pleotelson without setae.

Antenna 1 reaching pereonite 3, with 4 peduncular articles; article 3 longest and article 4 shortest; articulation of articles 3–4 oblique; flagellum of 13 articles (9 in damaged female); articles 3–13 bearing aesthetascs. Antenna 2 with peduncular article 4 longest; articles 1–4 each with group of long setae on anterodistal angle; flagellum with 16 articles (15 in damaged female).

Mandibular palp articles 2–3 with 12 pectinated setae each (9 and 11 respectively in the damaged female); setae of article 2 arranged in two rows. Maxilla 1 with 3 plumose robust setae on endopod and 12 curved robust setae and one slender seta on exopod. Maxilla 2 inner lobe with 7, medial lobe with 4, and outer lobe with 5 long plumose setae. Maxillipedal palp article 1 with 3 long plumose setae placed distally; articles 2–5 with 4, 12, 9, and 8 setae on medial margin respectively, usually plumose (simple setae if placed some way from the margin); lateral margin with 3, 7, 1, and 2 long simple setae respectively; endite with 3 lateral and 2 subterminal stout plumose setae, and 2 coupling hooks.

Pereopod 1 basis with 2 plumose setae on posterodistal angle; ischium with long seta on anterodistal angle and 3 long subterminal setae; merus with 3 long setae on anterodistal angle and subterminal seta, inner margin with 2 robust and 1 simple seta; carpus with 1 robust and 1 simple seta on inner margin, and 2 subterminal setae; propodus with 6 robust bifid setae interspersed with simple setae arranged in groups of 2–3; dactylus with distinct secondary unguis; row of 9 setae at base of unguis. Pereopods 2–3 shorter and more setose than pereopod 1; inner margin of merus-carpus-propodus with stout setae, especially in pereopod 2. Pereopod 4 robust, with stout setae on both anterior and posterior margins. Pereopods 5–7 similar, increasing in length posteriorly; numerous simple plumose setae and stout bifid setae on ischium-merus-carpus, especially in pereopod 7.

Pleopod 1 endopod narrow; peduncle with 4 coupling hooks and plumose seta on inner margin; endopod and exopod with 13 and 26 plumose setae respectively. Pleopod 2 peduncle with 3 coupling hooks and plumose seta; endopod and exopod with 13 and 33 plumose setae. Pleopods 2–5 peduncle increasingly short and rami progressively rounded. Pleopods 3–5 without setae on margin of endopod, and exopod with incomplete suture; endopod shorter than exopod.

Uropodal endopod rounded, flat, shorter than telsonic apex; 11 robust setae interspersed with stout setae on the margin of distal half. Uropodal exopod thin and concave surpassing telsonic apex; 5 robust setae on inner margin, apex with robust seta and a tuft of thinner setae, outer margin without robust setae. Tegument of exopod with simple setae and rounded scales with groups of short setae on their margin.

Color in alcohol pale with dorsal brown chromatophores.

Etymology. Beirutensis, from Beirut, capital of Lebanon.

Remarks. Atarbolana beirutensis sp. nov. has a uropodal exopod with a concave section like an elongated spoon; this feature, a spoon-like uropodal exopod without the cylindrical section found in the other species, is an autapomorphic character, and may be added to the generic diagnosis as a variable feature.

The genus Atarbolana Bruce & Javed, 1987 consists of 4 species ( A. exoconta Bruce & Javed, 1987 , A. setosa Javed & Yasmeen, 1989 , A. dasycolus Yasmeen, 2004 , and A. makranensis Khalaji-Pirbalouty, Naderloo & Keikhosravi, 2015 ) distributed in the Pakistani coast and Gulf of Oman (Iranian coast). A. beirutensis sp. nov. expands the distribution of this genus, which is recorded for the first time in the Mediterranean sea.

Figures

FIGURE 6. Atarbolana beirutensis sp. nov. Holotype female [MZB 2016 - 3479]: A, body, dorsal View; B, frontal lamina; C, distal end of body, dorsolateral View; D, apex of pleotelson; E, uropod, dorsal View; F, uropod, lateral View; G, antenna 1; H, antenna 2. Scale bars: A = 1 mm; B, F – H = 0.5 mm; C = 1.5 mm; D – E = 0.25 mm.

FIGURE 7. Atarbolana beirutensis sp. nov. Holotype female [MZB 2016 - 3479]: A, mandible; B, maxilla 1; C, maxilla 2; D, maxilliped; E, pereopod 1; F, pereopod 3; G, pereopod 5; H, pereopod 7. Scale bars: A – D = 0.1 mm; E – H = 0.25 mm.

FIGURE 8. Atarbolana beirutensis sp. nov. Holotype female [MZB 2016 - 3479]: A – E, pleopods 1 – 5. Scale bar: A – E = 0.25 mm.