Cephaloecetes ungulatus, Momtazi & Maghsoudlou & Just, 2018

Momtazi, Farzaneh, Maghsoudlou, Abdolvahab & Just, Jean, 2018, A new species of Cephaloecetes (Bubocorophiina) from the Iranian coasts of the Gulf of Oman and the Hormuz Strait (Crustacea: Amphipoda: Siphonoecetini), Zootaxa 4504 (1), pp. 128-134 : 129-133

Cephaloecetes ungulatus sp. nov.

Figures 1–3

Material examined. Holotype. Male , 4.8 mm. Iran, Gulf of Oman, 1.8 km (1 nm) west of Chabahar Bay, 25°16' N, 60°35' E, 7 m depth, sand, B. Løppenthin, stn 104, 31 March 1938, NHMD - 232541 (cleared in NaOH).

Paratypes. One male, same data as holotype, NHMD-232547. Four males and one female, Iran, Gulf of Oman, Chabahar Bay, 25°23'60"N, 60°27'36"E, 5.8 m depth, sand, 20 Oct. 2016, INIOC2- 4 S. Nine males, Iran, Gulf of Oman, Chabahar Bay, 25°23'60"N, 60°27'36"E, 5.8 m depth, sand, 14 Nov 2016, INIOC2- 5 S. One female, Hormuz Strait, Persian Gulf side, anchorage at Namakdan on Qeshm Island (Taoila), 26˚35’S 55˚29’E, 4 m, hard sand, G. Thorson, stn 70C, 19 April 1937, NHMD-232550. 1 male, Iran, Gulf of Oman, about 12 km (7 nm) WNW of Ras Makki, 25˚25’N 59˚28’E, 14 m, sand and some clay, B. Løppentin, stn 105, 1 April 1938, NHMD-232551 .

Etymology. Ungulates (ungula means claw in Latin) refers to the claw shaped ventral plate on antenna 2.

Description. Based on holotype, male.

Head as long as pereonite 1 and 1/2 of 2 combined along dorsal midline; ‘brows’ narrow; mid-anterior depression moderate 1/2 to 2/3 head length. Pseudorostrum slightly downward pointing in lateral view, in dorsal view slender, acutely pointed, about 2.5 times as long as broad at base, in dorsal view reaching beyond eye lobes with entire length. Eye lobes apically rounded in lateral view, lower anterior margin with two simple setae.

Antenna 1 as long as head and pereonites 1–5 combined, reaching to proximal 1/3 of antenna 2 peduncle article 5; peduncle article 1 with several short robust setae in row along medial margin; flagellum with 10 articles, as long as peduncle articles 1–2 and ½ of 3 combined. Antenna 2 approximately as long as head, pereonites and pleonite 1- 2 and half of 3 combined; ventral projection of peduncle of article 2 claw shaped with fringe of long simple setae laterally; article 3 medially with 4–5 transverse rows of simple setae and group of robust setae distomedially; article 4 with dorsal and medial rows of short robust setae, ventrally with dense rows of long simple setae; article 5 ventrally with about 12 groups of long simple setae; flagellum articles 1 and 2 with long robust setae.

Mouthparts, typical for genus. Mandible palp article 1 with a row of 6–7 medioventral long setae, a few dorsal and a tuft of apical setae.

Gnathopod 1 coxa anteriorly produced with long anterior and ventral setae; basis as long as propodus; ischium and merus combined as long as carpus; long robust seta on postero-distal angle of carpus; propodus length 2.8 times width, with 3 posterior robust setae. Gnathopod 2 carpus produced posteriorly between merus and propodus, with one robust seta on posterior margin; propodus length about 0.5 times width, with two robust seta on posterior margin of palm, the anterior one much larger than the proximal one. Pereopods 3–4 basis with long and short setae along proximal half of anterior and posterior margins. Pereopods 5–6 basis with row of long anterodistal setae. Pereopod 7 propodus anterior margin with 2 groups of short and long setae in distal half and apical dense group of long setae.

Uropod 1 peduncle with dorsolateral row of a few simple setae; outer ramus slender, slightly inward curved, about 0.5 times length of peduncle, lateral margin with 2 robust setae, peduncular corona finely fimbriate; inner ramus 0.7 length of outer ramus. Uropod 2 peduncle 0.4 times length of peduncle of uropod 1, lateral margin with 2 simple setae; ramus 0.5 times length of peduncle, reaching to about ramus of uropod 3, slender, straight, with an apical robust seta. Uropod 3 peduncle with weak median projection carrying a few simple setae, lateral margin with row of several unequally long simple setae; ramus with row of 4 unequally long setae. Telson distal margin straight, with two oval cuticular spinefields.

Female. Based on paratype, 4 mm, INIOC2- 4S.

Pseudorostrum shorter than in male. Uropod 1 peduncle with more simple setae, outer ramus with a few more robust setae. Sternal papillae in anterior half ventrally on pereonite 7 short, straight, length approximately twice width at base, forward pointing.

Size. Largest male, 4.8 mm; largest female, 4.0 mm.

Variation. In the studied material, there were some variations in robust setae on the distinctive antennae and other minor characters. These variations was considered as sexual or allometric variations.

Distribution. Iran, the Gulf of Oman: the Chabahar Bay and the Hormuz Strait: Qeshm Island.

Remarks. Just (2012) first described the genus Cephaloecetes based on C. enigmaticus from New South Wales and Victoria in south-eastern Australia. The key diagnostic character for the genus was the pseudorostrum arising from frons below an entire front margin of the head. The second member of the genus was Cephaloecetes schioettei Just, 2017b from the Philippines.

The present new species is characterized in the genus based on a unique claw-shaped ventral plate (vp) on the second article of antenna 2. Except for the different ventral plate Cephaloecetes ungulatus is most similar to C. enigmaticus , but it can be differentiated based on the longer first and second antennae, 2-3 robust setae in a group medioterminally instead of the normal character state for the genus with a single one on article 3 of antenna 2, 2 rows of small robust setae along article 4 of antenna 2, simple setae on peduncle of uropod 1 instead of row of robust setae, and lateral setae on uropod 3 peduncle.

The elongate coxal plates 1 and 2 and lack of robust setae on uropod 1 peduncle are shared between Cephaloecetes schioettei and C. ungulatus but the different ventral plate of antenna 2, short sternal papillae in females, and round eyelobes is characteristic of the new species from the Iranian coasts.

Just (2017b) mentioned that Cephaloecetes could be more widely distributed in the Indian Ocean. Cephaloecetes ungulatus thus extends the range of the genus to the Gulf of Oman and Hormuz Strait coasts of Iran in the north-western Indian Ocean.

Figures

FIGURE 1. Cephaloecetes ungulatus sp. nov. Holotype, ♂ (NHMD-232541). a2 flag, antenna 2 flagellum; c and ant dv, cephalon and antennae dorsal view; md palp, mandible palp; us, urosome; vp, ventral projection of article 2, antenna 2. Scale for habitus: 1 mm.

FIGURE 2. Cephaloecetes ungulatus sp. nov., H, holotype, ♂ (NHMD-232541); F, paratype, ♀ (NHMD-232550); M, paratype, ♂ (NHMD-232547). c and ant lv, cephalon and antennae lateral view; cdv, cephalon dorsal view; clv, cephalon lateral view; gp 1–2, gnathopods 1 and 2; p5, pereopod 5; up1 ped vv, uropod 1 peduncle ventral view; us, urosome.

FIGURE 3. Cephaloecetes ungulatus sp. nov., F, paratype, ♀ (INIOC2-4S); M, paratype, ♂ (from INIOC2-5S). c and ant2, cephalon and antenna 2 lateral view; cdv, cephalon dorsal view; md plp, mandible palp; sp, sternal papilla on pereonite 7; us, urosome; vp, ventral projection of article 2, antenna 2; vv, ventral view.