Pseudaeginella hormozensis, Momtazi, Farzaneh & Sari, Alireza, 2013

Momtazi, Farzaneh & Sari, Alireza, 2013, Intertidal caprellids (Crustacea: Amphipoda) of the Persian Gulf and the Gulf of Oman, with description of three new species, Zootaxa 3717 (2), pp. 195-223 : 210-216

Pseudaeginella hormozensis sp. nov.

( Figs 11–14 )

Material examined. ZUTC Amph. 2403, two males, two females, June 2010; ZUTC Amph. 2409, two males, one female, Loc 1 (Tiss, 25°21'21"N, 60°36'15"E) June 2011 & ZUTC Amph. 2409, three males and one female, Loc 39 (Hormoz Island, 27°1'58 "N, 56°28'21"E), January 2013.

Description. Holotype ♂. (ZUTC Amph. 2423, Hormoz Island, 27°1'58"N 56°28'21"E). Total length, 3.3 mm.

Lateral view ( Fig. 11 and Fig. 14 A). Head, 0.33 mm, and pereonite 0.23 mm; head and pereonite 1 fused, suture present. Head with a single dorsal anteriorly directed blunt projection; Pereonite 1 with one fine posterodorsal setose blunt projection; eye medium, distinctive. Pereonite 2 ( Fig 14 D), 0.5 mm with two fine setae on middorsal, and three fine setae on postero-dorsal surface and one pair of lateral projections at the base of Gn2. Pereonite 3 ( Fig. 14 E), 0.62 mm, largest, with one pair of lateral projections, two mid-dorsal and three posterodorsal fine setae. Pereonite 4 ( Fig. 14 F), 0.61 mm, with one pair lateral projection, one mid-dorsal, four posterodorsal fine setae and one lateral projection. Pereonite 5 ( Fig. 14 G), 0.5 mm with one pair of lateral projections below insertion of pereopod 5. Pereonite 6, 0.24mm, smooth. Preonite7, 0.21 mm, smooth.

Gill 3 length 0.32× pereonite 3, oval. Gill 4 length 0.35× pereonite 4, oval, longer than gill 3.

Mouthparts ( Fig. 12 ). Upper lip ( Fig. 12 UL) notched, wider than long, naked. Lower lip ( Fig. 12 LL) well developed, outer and inner lobes naked. Left mandible ( Fig. 12 LMd) incisor with 5 teeth followed by lacinia mobilis divided into numerous plates decreasing in size; molar absent; palp 3-articulate; article 2 with 3 simple setae; article 3 with setal formula 1+4+1, and a distal projection. Right mandible ( Fig. 12 RMd), incisor with 5 teeth and lacinia mobilis with 5 teeth; molar absent; palp 3-articulate; article 2 with 2 setae; article 3 provided with distal projection and setal formula 1+4+1. Maxilla 1 ( Fig. 12 Mx1) inner lobe with 6 stout apical setal-teeth, palp bi-articulate; distal article of the palp with 2 apical spines and 2 medial setae. Maxilla 2 ( Fig. 12 Mx2) outer plate with 5 apical setae, inner plate a little shorter with 4 apical setae. Maxilliped ( Fig. 12 Mxp) inner plate small and slender with 2 setae and 1 apically tooth and 1 spine at the base; outer plate reach to second palp article, with 4 apical setae and 2 medial setae; palp 4-articulate; first article with 1 seta, second with 5 setae, third with 7 setae and dactylus of palp slightly curved with minutely serrated on grasping margin.

Antennae ( Fig. 11 ). Antenna 1 ( Fig. 11 A1), 0.52× body length; peduncular article 1, 1.57× longer than third article; article 2 longest, 1.3 × longer than article 1; article 3 shortest; flagellum with 8 articles. Antenna 2 ( Fig. 11 A2) slightly longer than peduncle of antenna 1, about 0.6× length of antenna 1; article 1 with an acute projection distally; flagellum with 2 articles.

Gnathopods ( Fig. 11 ). Gnathopod 1 ( Fig 11 . Gn1) basis length two times as width; propodus triangular carrying a pair of grasping spines proximally; palm not serrate; dactylus reaching to end of palm with fine setae on inner and outer margins. Gnathopod 2 ( Fig 11 . Gn2) inserted in anterior half of pereonite 2; basis as long as pereonite 2; propodus length 2 times as width; palm convex with a small proximal projection, with a grasping spine and an acute projection medially.

Pereopods ( Fig. 12 ). Pereopod 3 ( Fig. 12 P3) reduced, uni-articulated and carrying a pair of unequal distal setae. Pereopod 4 ( Fig. 12 P4) as same as pereopod 3. Pereopod 5 ( Fig. 12 P5) well developed, propodus longer than carpus with a pair of grasping spines near proximal end of palm, dactylus falcate with several fine setae along inner and outer margins. Pereopods 6 and 7 ( Fig. 12 P6–7) similar in shape but pereopod 7 longer than pereopod 6.

Abdomen ( Fig. 11 Ab and Fig. 14 H, I) with a pair of lateral lobes and a single dorsal lobe. Penes large, apically cleft and medial-lateral lobes with three proximal setae and 8 medial setae, dorsal lobe with no seta.

Allotype ♀. (ZUTC Amph. 2424, Hormoz Island, 27°01'58"N 56°28'21"E). Total length, 2.58 mm.

Lateral view ( Fig. 13 ). Body surface as same as male. Antenna 1, 0.47× body length; peduncle article 2 longest; flagellum with 8 articles. Antenna 2 longer than peduncle of antenna 1; flagellum biarticulate.

Gnathopod 1 ( Fig. 13 Gn1) without sexual dimorphism. Gnathopod 2 ( Fig. 13 Gn2), basis as long as pereonite 2; palm convex with a small proximal projection with a pair of grasping spines without an acute projection medially. Pereopods 3–7 as same as male. Oostegite 3 length 1.3× width, setose along entire margin. Oostegite 4 length 1.21× width, naked. Abdomen ( Fig. 13 Ab) with two lateral lobs each of which with two setae and one dorsal lob with no seta.

Remarks. Pseudaeginella was characterized by: minute pereopods 3 and 4 and lacking abdominal appendages and synonymized with Fallotritella McCain, 1968 (Laubitz 1995) . Therefore P. biscaynensis , P. montouchetti and P. polynesica were previously described as a species of genus Fallotritella , and transferred to Pseudaeginella by Laubitz (1995).

Pseudaeginella hormozensis is a minute caprellid from the Gulf of Oman and the Persian Gulf and close to P. biscaynensis McCain (1968) that was described based on material from north Atlantic. However, there were other reports of P. biscaynensis from Tanzania (Guerra-García 2002c), Western Australia and Northern territory (Guerra- García 2004a) and Queensland (Guerra-García 2006) that show morphological variations especially on projection arrangement. Differences in dorsal projections in the Western Australia and Northern territory (Guerra-García 2004a) and Queensland material (Guerra-García 2006) could be considered as an age-related character. The western material with higher total length shows a dominant spine on pereonites 1–6 but in Queensland material only dorsal spines were reported on pereonites 1–2. Arimoto (1976) and Mori (1999) showed that spine arrangement varies in different growth stages in caprellids. McCain (1968) reported dorsal spines variations in P. biscaynensis without any mention of lateral projections or trace of them. The lateral spines only could be seen in P. hormozensis and Tanzanian material of P. biscaynensis (Guerra-García 2002c). Spines arrangement and robust pereopod 5 makes Tanzanian material completely different from other material of P. biscaynensis . It seems that a new species could be assigned for Tanzanian materials. Due to lack of complete descriptions and small size of Australian material (Guerra-García 2004a; Guerra-García 2006), taxonomic decisions about them are difficult and need more studies.

In the P. hormozensis material, the body length is smaller than in the McCain material and lateral projections are seen in pereonites 2–5. The species presented here was characterized from P. biscaynensis by reduced dorsal spines, possessing lateral projections on pereonites 2 – 5 (arrows in Fig. 14 D–G), robust pereopod 5 with grasping spines in propodus and 1+4+1 as setal formula. Pseudaeginella hormozensis and Tanzanian material of P. biscaynensis (Guerra-Garcia, 2002c) differ in setal formula and dorsal spines. Also the presence of a unique robust spine at the base of inner plate of maxilliped, and six stout setal-teeth on first maxilla, instead of five, discriminate P. hormozensis from other congeners. Table 4 shows differences between P. hormozensis and some records of P. biscaynensis .

Recently, Lacerda et al. (2011) re-described P. montoucheti and presented a key for species of the genus Pseudaeginella . They considered that in P. biscaynensis , the first antenna is longer than half of total length and the basis of second gnathopod are equal to second pereonite. But, McCain (1968) assigned the lengths of first antenna to pereonite 2–4 and the second antenna reaches to the end of peduncle in first antenna. In P. hormozensis the length of the first antenna is longer than pereonites 2–4 and the second antenna is longer than the peduncle of the first antenna.

Distribution. Pseudaeginella hormozensis was collected from two localities: the Gulf of Oman, Tiss harbor (Loc 1); the Persian Gulf, Hormoz Island (Loc 39).

Etymology. Description is done based on the collected materials from Hormoz Island, and the term of hormozensis is referred to this island.

Figures

FIGURE 11. Pseudaeginella hormozensis sp. nov. 3.3 mm. Holotype ZUTC Amph. 2423, Hormoz Island. Scale a = 0.5 mm and b = 0.1 mm.

FIGURE 12. Pseudaeginella hormozensis sp. nov. 3.3 mm. Holotype ZUTC Amph. 2423, Hormoz Island. Scale a = 0.5 mm and b = 0.05 mm.

FIGURE 13. Pseudaeginella hormozensis sp. nov. 2.58 mm. Allotype ZUTC Amph. 2424, Hormoz Island. Scale a = 0.5 mm and b = 0.1 mm.

FIGURE 14. Pseudaeginella hormozensis sp. nov. 2.58 mm. Holotype ZUTC Amph. 2423, Hormoz Island. A: dorsal view, B: first male gnathopod, C: second male gnathopod, D: second pereonite, E: third pereonite, F: forth pereonite, G: fifth pereonite, H – I: abdomen. arrows on D – G demonstrate lateral projections.