Protoaeginella paraspinipoda, Guerra-García, 2004

Guerra-García, José M., 2004, Deep-sea Caprellidea (Crustacea, Amphipoda) from Azores with the description of three new species, Zoosystema 26 (2), pp. 235-262 : 243-250

Protoaeginella paraspinipoda n. sp.

( Figs 6-9 )

TYPE MATERIAL. — Holotype: stn 120, (MNHN- Am 5257). Allotype: stn 120, (MNHN-Am 5258).

Paratypes: stn 120, 9, 5 (MNHN-Am 2948), and 16, 19 (MNHN-Am 2961).

ETYMOLOGY. — The specific name paraspinipoda refers to the species similarity to P. spinipoda Laubitz & Sorbe, 1996 .

DISTRIBUTION. — So far, only known from the Azores.

DESCRIPTION

Holotype, male (10.1 mm)

Lateral view ( Fig. 6A ). Head and pereonites with small tubercules. Eyes absent. Pereonite 1 fused with head although the suture between them is very distinct. Pereonites 2 to 5 increasing in length. Pereonite 7 the shortest.

Gills ( Fig. 6A ). Present on pereonites 3-4, elongate, length about five times width. A seta present near the base of the gills.

Mouthparts. Upper lip ( Fig. 7E ) symmetrically bilobate, with a row of minute setulae apically. Mandibles ( Fig. 7A, B ) with three-articulate palp; distal article of palp with a row of five plumose setae following the formula 1-3-1; mandibular molar present, strong; incisor and lacinia mobilis five-toothed; left mandible ( Fig. 7A ) with three plumose setae near lacinia mobilis and right mandible ( Fig. 7B ) with two plumose setae; molar flake present on right mandible, rectangular. Lower lip ( Fig. 7D ) inner and outer lobes well demarcated, with setulae; inner lobes round- ed. Maxilla 1 ( Fig. 7F ) outer lobe carrying seven spiniform setae; distal article of the palp with five robust setae apically and two medial setae. Maxilla 2 ( Fig. 7G ) inner lobe oval, carrying five setae distally; outer lobe rectangular, 1.3 times as long as inner lobe, with 10 apical setae. Maxilliped ( Fig. 7C ) inner plate carrying two nodular setae (short and robust like a tooth), two simple setae and five plumose setae, one of them small and robust and placed on the inner margin; outer plate oval, 1.8 times as long as inner plate, with four nodular setae, two distal apical simple setae and one lateral simple seta; palp four-articulate, second and third article setose.

Antennae. Antenna 1 ( Fig. 8A ) about one sixth of body length; distal article of the peduncle provided with a small accessory flagellum which carries two distal setae; flagellum six-articulate. Antenna 2 ( Fig. 8B ) without swimming setae; proximal peduncular article with acute projection distally; flagellum two-articulate.

Gnathopods. Gnathopod 1 ( Fig. 8C ) basis as long as ischium to carpus combined; propodus palm with a pair of grasping spines proximally; grasping margin of propodus palm with small setulae on the anterior end; dactylus serrate. Gnathopod 2 ( Fig. 8D ) inserted on the anterior half of pereonite 2 ( Fig. 6A ); basis 0.8 times as long as pereonite 2; ischium rectangular; merus rounded; carpus short and triangular; propodus elongate, as long as basis; palm with proximal projection provided with a single spine, followed by rows of small setulae and serrate margin on distal half; dactylus with smooth margin, provided with a row of tiny setulae.

Pereopods. Pereopods 3, 4 and 5 absent; a small knob with a single setae instead of pereopod 5. Pereopod 6 and 7 missing in male holotype ( Fig. 6A ) described from the female allotype ( Fig. 6B ).

Penes ( Fig. 9C ). Penes large and elongate, twice as long as width.

Abdomen ( Fig. 9C ). Abdomen with indistinct dorsal suture line, apparently two-segmented. A pair of appendages well developed, onearticulate, with two small seta medially and ending with five long teeth.

Allotype, female (7.3 mm)

Oostegites not setose ( Fig. 6B ). Genital papillae ( Fig. 6B ) with a distal seta. Palm of gnathopod 2 not serrated distally ( Fig. 8E ). Pereopod 6 ( Fig. 9A ) attached to the posterior end of the pereonite 6 ( Fig. 6B ), six-articulate, basis without carina, ischium short and rectangular; merus, carpus and propodus palm carrying row of short setae. Pereopod 7 ( Fig. 9B ) similar to pereopod 6. Abdomen ( Fig. 9D ) with a pair of small appendages one-articulate carrying a small distal seta.

REMARKS

The genus Protoaeginella was established by Laubitz & Mills (1972) based on the species P. muricata Laubitz & Mills, 1972 , collected from the Gay Head-Bermuda transect (North Atlantic) at 1330-4970 m. Recently, Laubitz & Sorbe (1996) described the second species of the genus, P. spinipoda from Bay of Biscay (North Atlantic) at 2990-3070 m. With the present study, so far, four species are known in the genus Protoaeginella : P. muricata , P. spinipoda and the new species P. paraspinipoda n. sp. and P. verrucosa n. sp., described in this paper.

The body length measured for the males of P. paraspinipoda n. sp. was 7.61 ± 1.33 mm (mean ± standard deviation) (range 5.45-10.10 mm). For the females it was 6.27 ± 0.61 mm (5.09-7.30 mm). In connection with the intraspecific variation, the morphological characters of antennae, mouthparts, gnathopods, pereopods and abdomen are constant in all the specimens examined, except for the lacinia mobilis in the right mandible, which can be five- or six-toothed, and the number of distal teeth in the appendages of the male abdomen which ranges from three to five.

Although the description and figures of Laubitz & Sorbe (1996) for P. spinipoda are clear and detailed, taking into account that P. paraspinipoda n. sp. is very close to P. spinipoda , the type material of P. spinipoda , deposited in the MNHN, have been consulted for comparison (holotype [MNHN-Am 4835], allotype [MNHN-Am 4836] and paratypes, 8 and 6 [MNHN-Am 4837]). Both species, P. spinipoda and P. paraspinipoda n. sp. are similar in the feature of the antennae, gnathopods and body proportions but can be distinguished mainly on the basis of the following characteristics, which are constant in all the specimens examined: 1) the body of P. spinipoda is almost smooth, without marked tubercles ( Fig. 10 ), whereas P. paraspinipoda n. sp. has small tubercles dorsally and laterally on the body ( Fig. 6 ); 2) the abdomen is three- to foursegmented in P. spinipoda ( Fig. 11 ), whereas it is indistinctly two-segmented in P. paraspinipoda n. sp. ( Fig. 9C, D ); and 3) the male appendages of the abdomen have nine or 10 apical teeth in P. spinipoda ( Fig. 11A ) and three to five apical teeth in P. paraspinipoda n. sp. ( Fig. 9C ).

Figures

FIG. 6. — Protoaeginella paraspinipoda n. sp., lateral view; A, male showing details of base of the gills and pereonite 5; B, female showing a detail of genital papillae. Scale bar: 1 mm.

FIG. 7. — Protoaeginella paraspinipoda n. sp., male mouthparts; A, left mandible; B, right mandible; C, maxilliped; D, lower lip; E, upper lip; F, maxilla 1; G, maxilla 2. Scale bars: 0.05 mm.

FIG. 8. — Protoaeginella paraspinipoda n. sp.; A-D, male; A, antenna 1; B, antenna 2; C, gnathopod 1; D, gnathopod 2; E, female gnathopod 2. Scale bars: 0.2 mm.

FIG. 9. — Protoaeginella paraspinipoda n. sp.; A, female pereopod 6; B, female pereopod 7; C, male abdomen; D, female abdomen. Scale bars: A, B, 0.5 mm; C, D, 0.1 mm.

FIG. 10. — Protoaeginella spinipoda Laubitz & Sorbe, 1996, lateral view; A, male showing a detail of pereonite 5; B, female showing a detail of genital papillae. Scale bar: 1 mm.

FIG. 11. — Protoaeginella spinipoda Laubitz & Sorbe, 1996; A, male abdomen; B, female abdomen. (Left: lateral view; right: ventral view). Scale bar: 0.1 mm.