Talorchestia qeshm, Lowry, Jim & Momtazi, Farzaneh, 2015

Lowry, Jim & Momtazi, Farzaneh, 2015, Talorchestia qeshm sp. nov., a new talitrid amphipod from the Persian Gulf (Amphipoda, Talitridae), Zootaxa 3985 (3), pp. 432-439 : 433-438

Talorchestia qeshm sp. nov.

( Figs 1–4 )

Types. Holotype male, 16 mm, AM P.97750, Qeshm Island, southern Persian Gulf, Iran (approx. 26°30’N 55°48’E), supralittoral, coll. F. Momtazi, 2013. Paratypes: 1 female, ovigerous, 13 mm, AM P.97751, 1 adult male, 2 juvenile males, 6 females, AM P.97752, same locality as holotype.

Other material examined. 25 females, 4 males and 5 juveniles, INIOC 1-23S, same locality as types.

Type locality. Qeshm Island, Persian Gulf, Iran (approx. 26°30’N 55°48’E), supralittoral zone.

Etymology. Named for type locality, as a noun in apposition.

Ecological type. Beach-hoppers (coastal supralittoral/intertidal leaf-litter/wrack, non-substrate modifying talitrids).

Description. Based on holotype, male, 15 mm, AM P.97750.

Head with 5 groups of long, scales (damaged) along ventroproximal surface. Antenna 1 short, reaching about half length of peduncular article 4 of antenna 2. Antenna 2 more than half body length; peduncular articles slender, article 5 longer than article 4, peduncular articles with many small robust setae; flagellar articles, final article large, cone-shaped, with apical cluster of 'imbricated' setae. Labrum with apical setal patch; epistome without robust setae, with many pores. Labium distolateral setal tuft absent, with vestigial inner plates. Mandible left lacinia mobilis 5-cuspidate (fifth tiny). Maxilla 1 with small palp, 1-articulate. Maxilliped palp article 2 distomedial lobe well developed; article 4 fused with article 3.

Pereon. Gnathopod 1 sexually dimorphic; parachelate; coxa smaller than coxa 2; posterior margin of carpus and propodus each with lobe covered in palmate setae, palmate lobes in male only; carpus longer than propodus, 1.6 × as long as propodus, 2.5 × as long as broad; propodus subrectangular, anterior margin with 6 groups of about 16 robust setae, medial surface with 6 cuspidate setae; palm with 3 serrate setae, palm obtuse, without spine patch on posterodistal corner; dactylus longer than palm, simplidactylate, without anterodistal denticular patch. Gnathopod 2 sexually dimorphic; subchelate; basis slender; ischium with weak rounded lobe on mid-anterior margin, without anterodistal lobe on medial surface; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; carpus triangular, reduced (enclosed by merus and propodus), posterior lobe absent, not projecting between merus and propodus; propodus subovate, 1.8 × as long as wide, palm acute, reaching about 54% along posterior margin, smooth, without protuberance or shelf near dactylar hinge, lined with robust setae, posteroproximal corner with groove, without cuticular patch at corner of palm; dactylus subequal in length to palm, broadly curved, without anteroproximal bump, posterior margin with posteroproximal sinus and small projection. Pereopods 2–4 coxae as wide as deep. Pereopods 3–7 cuspidactylate; dactyli without anterodistal patch of many rows of tiny setae. Pereopod 4 significantly shorter than pereopod 3; carpus significantly shorter than carpus of pereopod 3; dactylus thickened proximally with a strong notch midway along posterior margin. Pereopod 5 propodus distinctly longer than carpus. Pereopods 6–7 not sexually dimorphic. Pereopod 6 shorter than pereopod 7; coxa posterior lobe inner view posteroventral corner rounded, posterior margin oblique to ventral margin, posterior lobe with ridge, posterior lobe with 12 marginal setae. Pereopod 7 basis lateral sulcus present, slightly pronounced, posterodistal lobe present, shallow, broadly subquadrate; distal articles (merus and carpus) slender.

Pleon. Pleopods 1–3 biramous, all well developed. Epimeron 1 with 2 small robust setae on the anteroventral margin. Epimeron 2 subequal in length to epimeron 3. Epimeron 3 posterior margin smooth, with minute setae, posteroventral corner with well developed subacute tooth, ventral margin without robust setae. Uropod 1 peduncle with 10+ robust setae, distolateral robust seta present, small (less than 1/4 length of outer ramus), with simple tip; inner ramus subequal in length to outer ramus, inner ramus with about 12 marginal robust setae in 2 rows; outer ramus without marginal robust setae. Uropod 2 not sexually dimorphic; inner ramus slightly shorter than outer ramus, with 4 lateral and 3 medial marginal robust setae; outer ramus with 2 marginal robust setae in 1 row. Uropod 3 peduncle with 9 robust setae; ramus partially fused dorsally to peduncle, ramus shorter than peduncle, 2.4 × as long as broad, linear (narrowing distally), with 3–4 marginal robust setae and 5 apical setae. Telson apically incised, dorsal midline entire, with 10–11 marginal and apical robust setae per lobe.

Female (sexually dimorphic characters). Based on paratype, female, 11.3 mm, AM P. 97751. Antenna 2 less than half body length; peduncular article 5 subequal to article 4. Gnathopod 1 simple; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; carpus 2.9 × as long as broad; propodus anterior margin with 4 groups of 12 robust setae. Gnathopod 2 mitten-shaped; basis expanded anteromedially; ischium without lobe on anterior margin; posterior margin of carpus and propodus each with lobe covered in palmate setae; carpus well developed (not enclosed by merus and propodus), posterior lobe present, projecting between merus and propodus; propodus twice as long as wide, palm obtuse; dactylus shorter than palm, straight, posterior margin smooth, not modified distally, blunt. Oostegites long than wide (length greater than 2 × width), weakly setose (14– 18), setae with simple smooth tips.

Remarks. Talorchestia qeshm sp. nov. belongs to the group of three species, including T. martensii and T. morinoi , in which the propodus of the male gnathopod 1 does not have a protuberance near the dactylar hinge, the left lacinia mobilis has 5 cusps, antenna 2 is more than half, but not exceeding the body length and epimeron 3 has a well developed subacute tooth on the posteroventral corner.

Within this group T. qeshm differs from T. martensii in the male gnathopod 2 coxa which has a convex anterior margin (straight in T. martensii and T. morinoi ) and the ischium which has a weak, rounded lobe on the anterior margin (subacute lobe in T. martensii ), in urosomite 3 which is larger than the uropod 3 peduncle (subequal in size for T. martensii and T. morinoi ), in the uropod 3 peduncle with 8–9 robust setae (5 in T. martensii ) and in the telson with 10–11 robust setae per lobe (8–9 in T. martensii ).

Talorchestia qeshm is a larger species (15 mm) than T. morinoi (9.6 mm) with a shorter carpus on male gnathopod 2 (2.5 × breadth in T. qeshm , 3.1 × breadth in T. morinoi ) and a posteroproximal sinus and small projection on the dactylus (with shallow posteroproximal sinus in T. morinoi ); the peduncle of uropod 3 has 8–9 robust setae (6 in T. morinoi ); and an elongate, longer than broad, telson (broader than long in T. morinoi ).

In the female of T. qeshm the palm of gnathopod 1 is covered in small setae and robust setae line the margins (without small setae and robust setae in T. martensii and without small setae and only a few robust setae in T. morinoi ), the basis of gnathopod 2 is expanded anteriorly in T. qeshm and T. martensii (expanded anteriorly and posteriorly in T. morinoi ).

Othman & Azman (2007) discussed the differences between T. martensii and T. morinoi .

It is interesting that such closely related species are spread over such a wide geographic range. This might be explained by the nearly continuous horizontal coastline through a similar tropical/subtropical environment which allowed the distribution of a common ancestor.

Distribution. Iran. Persian Gulf (current study).

Figures

FIGURE 1. Talorchestia qeshm sp. nov., male, holotype, 15 mm, AM P. 97750, Qeshm Island, Persian Gulf. Scale line for H represents 0.5 mm, remainder represent 0.1 mm.

FIGURE 2. Talorchestia qeshm sp. nov., male, holotype, 15 mm, AM P. 97750, Qeshm Island, Persian Gulf. Scale lines represent 0.5 mm.

FIGURE 3. Talorchestia qeshm sp. nov., male, holotype, 15 mm, AM P. 97750, Qeshm Island, Persian Gulf. Scale lines represent 0.5 mm.

FIGURE 4. Talorchestia qeshm sp. nov., male, holotype, 15 mm, AM P. 97750, female, paratype, AM P. 97751, Qeshm Island, Persian Gulf. Scale lines represent 0.5 mm.