Atarbolana makranensis, Khalaji-Pirbalouty, Valiallah, Naderloo, Reza & Keikhosravi, Alireza, 2015

Khalaji-Pirbalouty, Valiallah, Naderloo, Reza & Keikhosravi, Alireza, 2015, Atarbolanamakranensis, a new species of Cirolanidae (Crustacea, Isopoda) from Makran, Iranian coast of the Gulf of Oman, ZooKeys 522, pp. 129-140 : 132-138

Taxon classification Animalia Isopoda Cirolanidae

Atarbolana makranensis sp. n. Figs 2, 3, 4, 5, 6

Material examined.

Holotype: ♂ (4.4 mm) Gatan-Paein, Hormuzgan Province, Iran, Gulf of Oman, rocky intertidal shore covered with algae, 25°58'1.52"N, 57°15'13.78"E, 27 December 2013, coll. V. Khalaji-Pirbalouty, R. Naderloo ( ZMH–K– 42597). Paratypes: 5 ♂♂ (4.9, 4.4, 3.9, 3.8, 3.7 mm), 1♀ (ovig. 3.5mm), 9 ♀♀ (3,0-3.8 mm), same data as holotype (ZUTC 5481); 1♂ (3.6 mm), 4 ♀♀ (2.5, 2.6, 2.8, 3.0 mm), same locality as holotype, 30 June 2013, coll. V. Khalaji-Pirbalouty, R. Naderloo (ZUTC 5482).

Diagnosis.

Body 2.3 times as long as greatest width; pereonites 5-7, pleon and pleotelson bearing scattered small tubercles; flagellar articles 1-10 in male bearing a tuft of long serrate and simple setae; pleotelson elongated, with narrowly rounded apex, posterior margin with 12 marginal RS; uropod peduncle ventro-mesial surface with a row of 8 RS, uropodal endopod not reaching to pleotelson apex, with 14-15 (left/right) marginal RS, lateral margin proximally lacking RS, exopod about two times as long as endopod; appendix masculina with an acute apex, arising above mid-point of endopod medial margin, and extending slightly beyond endopod distal margin.

Description of male.

Body 2.3 times as long as greatest width, widest at pereonite 5 (Fig. 2A). Head with acute rostral point, with 2 sutures posteriorly. All pereonites posterior margins bearing long simple marginal setae; pereonite 1 with 2 curved furrows laterally (Fig. 2B); pereonites 5-7 bearing scattered small tubercles; pereonites 2-3 with sub-quadrate coxal plates; coxal plates 5-7 progressively more produced and acute posteriorly, produced beyond posterior margin of respective segment; all coxal plates with entire, oblique carina, all coxal plate ventral margin fringed with long simple setae (Fig. 2B).

Pleon (Fig. 2A) with pleonite 1-2 concealed by pereonite 7; pleonite 3 visible dorsally; pleonite 4 extended well over lateral margins of pleonite 5 and proximal part of uropodal peduncles, pleonites 3-5 with scattered small tubercles.

Pleotelson (Fig. 2A, E, F) progressively upturned into a narrowly rounded apex, with 2 bimedian depressions, dorsal surface with scattered small tubercles; posterior margin bearing 12 marginal RS set between long PMS; apical marginal RS concealed by apical margin, distally with 3 small marginal setae (Fig. 2E, F).

Antennule (Fig. 2C) extending to posterior margin of pereonite 3, peduncle article 1 short, peduncle article 3 approximately 1.5 times as long as article 2; flagellum with 15 articles, articles 7-15 bearing 1 or 2 aesthetascs.

Antenna (Fig. 2D) peduncle articles 2-4 subequal in length, all articles each with a group of long simple setae on antero-distal corner, article 3 with 5-6 very long simple setae on ventral margin; flagellum with 17 articles, extending to posterior margin of pereonite 1, articles 1-10 bearing a tuft of long setae (some serrated), distoventral corner with a single long simple seta.

Left mandible (Fig. 3A) molar process anterior margin with about 33 flat teeth; spine row composed of 9 spines; palp article 2 longest with 10 robust biserrate setae and 2 robust simple setae, article 3 with 10 robust biserrate marginal setae.

Maxillule (Fig. 2B) lateral endite with 10 RS (weakly serrated) and 2 slender setae; mesial endite with 3 large circumplumose RS and 2 short simple setae.

Maxilla (Fig. 3C) lateral and middle endites each with 5 long finely plumose setae; mesial endite with 7 long circumplumose RS and 2 small simple RS.

Maxilliped palp (Fig. 3D) article 1 with 6 distally placed long setae, articles 2-5 lateral margins with 2, 7, 2 and 2 slender simple setae respectively; articles 3- 5 with continuous fringe of finely biserrate setae on medial margin; endite (Fig. 4E) with 4 long CPS, and 2 coupling hooks.

Pereopod 1 (Fig. 4A) basis 3.4 times as long as wide, superior margin with 3 long simple and 2 SPS, posterodistal angle with 3-5 long finely plumose setae; ischium inferior margin with 2 long simple setae, mediodistal margin with 3 long simple setae; merus inferior margin with 3 RS and 1 long simple setae, medio-distal margin with 1 long simple setae, superior margin with 3 long simple setae; carpus triangular, inferior margin with 2 RS and 4 long simple setae; propodus inferior margin with 10 RS and 3 sets of sub-marginal slender simple seta, superior margin with a single simple seta, superodistal angle with 2 simple and 1 plumose setae; dactylus with minute secondary unguis, bearing a transverse row of 8 simple setae at base.

Pereopod 2 (Fig. 4B) basis 2.5 times as long as wide, superior margin with 5 long simple and 3 SPS, posterodistal angle with 5 long finely plumose or simple setae; ischium inferior margin with 6 long simple setae, mediodistal margin with 3 long simple setae, superior margin with 3 long simple setae; merus inferior margin with 4 RS and 4 long simple setae, superodistal angle with 5 long setae, mediodistal margin with 2 long simple setae; carpus triangular, inferior margin with 2 RS and 3 long simple setae; propodus inferior margin with 7 robust and 2 sets of sub-marginal slender simple setae, superior margin with a single simple seta, supero-distal angle with a SPS and 3 simple setae; dactylus with minute secondary unguis, bearing a transverse row of several simple setae at base.

Pereopod 3 (Fig. 4C) similar to pereopod 2.

Pereopod 4 (Fig. 4D) basis 2.3 times as long as wide, with 5 long simple submarginal and 2 SPS, postero-distal angle with 3 long simple setae and 2 long finely biserrate setae; ischium supero-distal angle with 2 long RS, supero-medial surface with 4 long simple setae, inferior margin with 2 sets of RS and 2 sets of long simple sub-marginal setae; merus inferior margin with 2 sets of RS (1 + 7), superior distal angle with 3 RS and 1 long simple seta; carpus inferior distal margin with 6 simple or serrated RS, superior distal angle with 2 RS; propodus inferior margin with 3 RS, superior distal angle with 1 SPS and 2 simple setae; dactylus with minute secondary unguis, sub-marginal row of 3 simple setae.

Pereopod 5 (Fig. 5A) and Pereopod 6 (Fig. 5B) are similar to pereopod 4 as illustrated.

Pereopod 7 (Fig. 5C) basis 2.5 times as long as wide, postero-distal angle with 1 serrated RS and 4 long simple setae; ischium superior distal angle with 5 biserrate or simple RS, medial surface with 3 rows of long simple setae, inferior margin with 3 sets RS and 2 sets long simple sub-marginal setae; merus and carpus superior and inferior margins fringed with numerous long plumose setae; propodus inferior margin with 2 sets robust setae, superior distal angle with 1 RS, I simple and 1 SPS; dactylus with minute secondary unguis.

Pleopod 1 (Fig. 6A) exopod and endopod with ~39 and 16 PMS, endopod longer and narrower than exopod; sympod 1.5 times as wide as long, mesial margin with 4 coupling hooks and 1 plumose seta, lateral margin with a single RS.

Pleopod 2 (Fig. 6B) exopod and endopod with ~54 and 10 PMS respectively; appendix masculina arising above 0.6 of endopod medial margin, extending slightly beyond endopod distal margin (by approximately 0.2 times of length), tapering to an acute apex; sympod mesial margin with 3 coupling hooks and 1 plumose seta, lateral margin with a single sub-marginal RS.

Pleopod 3 (Fig. 6C) and Pleopod 4 (Fig. 6D) essentially similar, exopod with ~51 and ~58 PMS, and an entire transverse suture; sympod medial margin with 3 coupling hooks and 1 plumose seta, lateral margin with single sub-marginal RS.

Pleopod 5 (Fig. 6E) exopod with 56 plumose marginal setae, and entire transverse suture; sympod without coupling hook, lateral margin with single sub-marginal RS.

Penes (Fig. 6F) short, separate but adjacent, 2.5 times as long as basal width.

Uropod (Fig. 5D); endopod not reaching to pleotelsonic apex, with 14-15 (left/right) marginal RS, lateral margin proximally lacking RS; exopod (Fig. 5E) elongate, slender, nearly 2 times as long as endopod, extended well beyond pleotelsonic apex, dorso-lateral margin with 3 RS, ventro-medial margin with 4 RS, distal margin with a tuft of long simple setae, 1 prominent RS and 1 small RS; peduncle ventral side with a single long RS distally, ventro-medial surface with a row of 8 RS and 2 long plumose setae.

Female. Apart from sexual characters differs from male by having an antenna without tuft of long setae on flagellum articles; uropod rami smaller than in male and extending just beyond the pleotelsonic apex, endopod with 12 marginal RS (rather than 14 in male); pleotelson with 8 marginal RS (rather than 12 in male), elongation less than in male.

Variations.

Pleotelson marginal RS (n = 14 [7♂ and 7♀]) males with 10-12 RS, with 12 RS (86%) most frequent, and 10 (14%) occurring only once; in females with 8-9 RS, with 8 RS most frequent (71%), and 9 (28%). Uropod endopod in males with 14-15 RS, with 14 RS (86%) most frequent, and 15 (14%) occurring only once; in females with 12-13 RS, with 12 RS (86%) most frequent, and 13 (14%) occurring only once.

Remarks.

Atarbolana makranensis sp. n. can be identified by the elongate pleotelson with a narrow apex and 12 marginal RS in male. The ventral surface of the uropod peduncle with a row of 8 RS, uropodal endopod not extending to apex of the pleotelson, about half length of exopod, lateral margin lacking RS proximally. Atarbolana makranensis sp. n. is similar to Atarbolana setosa Javed and Yasmeen (1989), and Atarbolana dasycolus Yasmeen, 2004 (both described from Karachi, Pakistan), in having an antennal flagellum with tufts of long and dense setae. However, the two species can be clearly distinguished from Atarbolana makranensis by having an elongated appendix masculina which extends well beyond the apex of the endopod of the pleopod 2. Furthermore, in the new species the pleotelson extends well beyond the uropodal endopod, whereas in Atarbolana setosa the pleotelson extends just to the endopod apex. Atarbolana dasycolus has a pleotelson with 8 marginal RS and does not extend to the endopod apex. In addition, in Atarbolana makranensis the uropod exopod/endopod ratio is approximately 2, whereas it is 1.7 in Atarbolana setosa and 1.35 in Atarbolana dasycolus . Based on the drawings and description of Atarbolana exoconta , the type species of the genus, given by Bruce and Javed (1987) and examination of paratype material (AM. P.37200, P.37276, Manora Island, Pakistan), Atarbolana exoconta differs from Atarbolana makranensis in having a shorter pleotelson with 16 marginal RS, lacking long setae on the antennal flagellum, and a lower uropod exopod/endopod ratio (1.34).

Etymology.

The specific epithet of the new species refers to its type locality, Makran, which is the name of the area with the original Aryan people living in the southeast of Iran along the coast of the Gulf of Oman.