Perepsilonema benguelae, Hendricks, Martin G. J. & Gibbons, Mark J., 2010

Hendricks, Martin G. J. & Gibbons, Mark J., 2010, Two new nematode species from Saldanha Bay, South Africa: Perepsilonema benguelae sp. nov. and Leptepsilonema saldanhae sp. nov. (Desmodorida, Epsilonematidae), Zootaxa 2504, pp. 20-30 : 21-24

Perepsilonema benguelae sp. nov.

( Figs 1 , 2 )

Measurements: Table 2.

Material examined: Holotype male: South Africa, Saldanha Bay, -33.04800°, 17.98350°, coarse sand in shipping channel, sublittoral (20 m), collected August 1999 by MGJ Hendricks (SCUBA-assisted handheld corers), NHM accession No. 2008:860. Paratypes: one female NHM accession No. 2008:861, five females Iziko South African Museum accession No. SAM A29471 .

Holotype Male Females (n = 6)

Mean SD Range L 352 321 26.5 266-334 N 118 124 7 112-131 amph 3 3 0.63 2.6-3.9 amph % 37 29 5 23.5-35.3 ph 56 56 2.9 52-59 mbd ph 33 30 2.9 27-36 mbd 39 39 3 33-42 (mbd) 14 15 2.2 12-19 abd 15 16 1.5 15-19 t 21 27 1.8 25-29 tmr 10 11 1.9 8-14 spic 48 - - - gub 7 - - - a 8.9 8.0 0.2 7.7-8.2 b 6.3 5.5 0.3 5.1-6 c 17 11.4 0.9 10.2-12.8 c' 1.3 1.7 0.2 1.3- 2 V - 68 2.9 65-73 mbd/(mbd) 2.9 2.6 0.5 2.2–3.3

Male. Body epsilon-shaped ( Fig. 1 A), swollen in cloacal, testis and pharyngeal regions. Cephalic capsule tapering anteriorly, truncated posteriorly; tail short, conical. Body with 118 pronounced annulations ( Table 2), not clearly orientated either anteriorly or posteriorly, with prominent box-like vacuoles in swollen portions of body. External layer of cuticle thickened ventrally in testis region, with fine longitudinal markings. Somatic setae (10.3 µm long) regularly spaced in six rows, anterior to the first curvature. Tail short, with one ventrally directed seta (2.6 μm long) on non-annulated section and two short setae (2 μm long) on the last two annulated segments. Three pairs of small, conical, pre-cloacal thorns present.

Cephalic capsule conical, 14 µm in diameter at base and 9 µm long ( Fig. 2 A). Labial papillae not seen (lip region is retracted in only specimen). Four cephalic setae of equal length (5 µm), not at same level; dorsolateral pair more anterior to ventro-lateral pair. Eight subcephalic setae on cephalic capsule; one pair present at base of amphidial fovea, longer (6.5 µm) than others (3 µm).

Amphidial fovea at base of cephalic capsule, extending to about 38% of corresponding body diameter, comprising a dorso-ventrally wound loop; canalis situated in centre of spiral fovea. Buccal cavity indistinct, with small tooth; pharynx muscular, 56 µm in length with cuticularised lumen and prominent terminal bulb. Cardia 2.6 μm long, opening into bulbous intestine.

Single outstretched testis ventral to alimentary canal, extending posterior to the narrow middle section of the body ( Fig. 2 C); vas deferens well defined. Spicules 48 µm long, curved with well-developed “hammerlike” capitulum; velum not observed. Gubernaculum short (7 µm long), parallel to spicules. Two ventral rows of small thorn-like structures present on 7th, 8th and 9th annuli anterior to cloacal opening. Prominent laterally-placed somatic setae (6 µm long) present on 2nd (not shown in Fig. 2 C) and 6th annuli anterior to cloaca.

Female. Broadly similar to male in general form, shorter ( Table 2). Body wide in anus, ovary and pharynx regions ( Fig. 1 B). Number and ornamentation of annuli similar to males, but change in orientation pronounced at 88th annulation in the region of the vulva. Cephalic capsule narrower than male, 12 µm wide, 9.5 µm long ( Fig. 2 B), with amphidial fovea at base. Amphidial fovea different from male, a single coil with canalis situated in centre of spiral fovea; extending to about 29% of corresponding body diameter. Buccal cavity small, one specimen with a minute tooth; pharynx muscular, with prominent terminal bulb.

Reproductive system didelphic, amphidelphic, reflexed; ovaries with tips bent to opposite sides of the intestine (anterior ovary to the right, posterior to the left). Ovarian system ventral to alimentary canal ( Fig. 2 D). Uterine chamber medially situated, containing a number of sperm cells. Vagina sclerotized along entire length, terminating at uterus, surrounded by constrictor muscle.

Type locality and habitat. Course-grained sediments in Saldanha Bay, at a depth of 20 m.

Diagnosis. Perepsilonema benguelae sp. nov. is a medium-sized nematode with eight subcephalic setae; annulations not clearly orientated either anteriorly or posteriorly in the male and with box-like vacuoles,; tail short, c = 17; short spicules and gubernaculum. The body is similar in length to P. papulosum , P. c r a s s u m, P. moineaui , but the annulations fewer than P. papulosum and more numerous than P. moineaui . copulatory thorns are absent from the mid-body region at level of testis, as in P. papulosum and P. m o i n e a u i, whereas three pairs of copulatory thorns occur in the precloacal region in P. t r a u c i. The absence of copulatory thorns at the level of testis in the mid-body region, the presence of three pairs of copulatory thorns in the precloacal region, and the lack of subdorsal post-cloacal caudal spines together with the short spicules and gubernaculum are diagnostic characters for P. benguelae sp. nov.

Etymology. The species is named after the Benguela Current, flowing along the west coast of southern Africa.

Figures

FIGURE 1. Perepsilonema benguelae sp. nov. A. Male habitus. B. Female habitus. Scale represents 50 μm.

FIGURE 2. Perepsilonema benguelae sp. nov. A. Male anterior body region with indication of amphidial fovea and detail of body rings in surface view. B. Female anterior body region with indication of amphidial fovea and detail of body rings in surface view. C. Male posterior body region with reproductive system. D. Female posterior body region with reproductive system. Scale represents 20 μm.