Bathyzetes umbrella, Bamber, Roger N., 2004

Bamber, Roger N., 2004, Pycnogonids (Arthropoda: Pycnogonida) from French Cruises to Melanesia, Zootaxa 551, pp. 1-27 : 4-8

Bathyzetes umbrella sp. nov. ( Figs 2–3 )

Material: Solomon Islands: 1 male?, holotype (MNHN­Py 1036), 6 males, 4 gravid females, 3 subadults (MNHN­Py 1037), 2 males, 1 gravid female (NHM.2003.640–642), paratypes, station CP1781, N/ O 'Alis' Campagne SALOMON 1, 08º31.2'S 160º37.7'E, 1036–1138 m, 29/09/2001; coll. Bouchet, Dayat, Warén, Richer­IRD.

Description of male: trunk ( Fig. 2 A, B) attenuate, completely segmented, without dorsal tubercles, heavily setose, including long setae (more than twice trunk diameter in length) dorsodistally on lateral processes, and mid­dorsally on flared posterior margins of trunk segments and at base of abdomen. Lateral processes longer than trunk diameter, separated by about twice their own diameter. Cephalon shorter than any other trunk segment; no ocular tubercle. Oviger implantation just anterior to first lateral processes. Abdomen articulated at base, slender, setose, downcurved, its tip exceeding half the length of second coxa of fourth leg. Proboscis bulbous without constrictions, about half length of trunk.

Chelifores of two setose articles, proximal article almost twice length of distal article; chela atrophied, with short, stubby fingers ( Fig. 2 C).

Palp ( Fig. 2 D) of 10 articles; article 3 longest, articles 4 and 6 very short, article 5 0.7 times article 3, distal four articles subequal, slender, elongate; distal five articles with dense row of ventral setae.

Oviger ( Fig. 3 A, B) articles 4 and 5 subequal, segment 6 0.6 times length of article 4; articles 7 to 10 with compound spines in one or two rows, main row comprising 7, 3, 3 and 4 spines respectively; terminal claw stout, simple, two­thirds length of article 10, not pseudo­chelate with distal oviger spine.

Third leg ( Fig. 3 C) first and second coxae subequal, with rows of ventral setae and longer dorsal setae, of length up to 6 times coxa diameter; third coxa less than half length of first coxa, without long setae; femur and first tibia subequal, with shorter ventral setae and long dorsal setae, those on distal half of femur as on first two coxae. Distal three articles with setose ventral margin, but without longer dorsal setae; second tibia 0.7 times length of first tibia, tarsus about half length of propodus, propodus half length of second tibia; main claw ( Fig. 3 D) half length of propodus, with rounded denticulations along ventral margin; no auxiliary claws. Many longer dorsal setae with broken tips, but entire longer setae of first and second coxae and femur (as also on trunk) with complex distal barbs ( Fig. 3 E) comprising rounded tip bearing more than ten proximally oriented fine spinules. Cement gland orifices not seen, but opaque tissue apparent within femur (not apparent in gravid females or smaller subadults).

Female generally similar, but with stouter femur and slightly shorter oviger.

Measurements of male (mm): trunk length (anterior of cephalon to tip of 4th lateral process) 6.67; length of cephalon 1.17; width across 2nd lateral processes 5.65; proboscis length 3.17; abdomen length 4.33; chelifore article 1 length 2.08; chelifore article 2 length 1.38; palp article 3 (P3) 1.03, P5 0.71, P8 0.4; third leg, first coxa 1.39, second coxa 1.44, third coxa 0.56, femur 3.17, first tibia 3.22, second tibia 2.28, tarsus 0.53, propodus 1.14, main claw 0.54; oviger article 4 ( O 4) 1.2, O 5 1.23, O 6 0.77.

Etymology: “ Umbrella ” from the Latin umbra, via the Italian ombrella, a portable shelter from precipitation, now commonly made on a wire framework: the latter is the shape of the peculiarly barbed tips to the long spines of this species.

Remarks: The nine mature specimens which were not gravid females (including the holotype) all had a slender femur containing opaque tissue; although no cement gland orifices were apparent, these are assumed to be males.

The genus Bathyzetes was erected by Stock (1955) to accommodate species previously assigned to Eurycyde Schiödte, 1857 but which had no separate proboscis peduncle, nor ocular tubercle, and ungrouped abdominal setae. They are distinguished from Ascorhynchus rather tenuously on the basis of their particularly elongate and setose chelifores. Of the three known species, B. extenuata ( Calman 1938) from Zanzibar is known only from the juvenile holotype. B. setigera ( Loman 1908) , the type of the genus, and B. virago ( Loman 1908) are recorded from Indonesia, and these two have the distal oviger spine on oviger article 10 enlarged to form a “pseudo­chela” with the terminal claw ( Stock 1955, figure 24). Neither B. umbrella sp. nov. nor B. extenuata have such a pseudochela, though in the case of the latter that may be by reason of its immaturity. Nevertheless, its seems useful to maintain the distinction of these undoubtedly similar species from Ascorhynchus .

Bathyzetes umbrella is readily distinguished from the other species owing to its cephalon being shorter than the other trunk segments (as long as or longer than the other trunk segments in the other species), its abdomen extending to more than half the length of the second coxa of the fourth leg (only just exceeding tip of first coxa in the other species, owing to the more elongate coxae), and oviger article 5 longer than article 4. Other differences, such as shorter proboscis and abdomen in relation to the trunk (also the case for B. extenuata ), the proportionately shorter distal chelifore article, and the proportions of the palp and oviger articles (P6 much shorter, O 6 much longer in B. umbrella ) are summarized in Table 1 (see also Loman 1908; Calman 1938).

The peculiar barbed tips to the long setae may be common to the genus, as Loman alludes (but in less detail) to something similar (“winziger Knötchen”) in both of his species. Bathyzetes extenuata is without the long setation of the other species.

Stock (1991) recorded specimens of Bathyzetes setigera from New Caledonia, which may in fact prove to be of this new species.

Figures

FIGURE 2. Bathyzetes umbrella sp. nov., holotype male, A, body, lateral; B, body dorsal; C, right chela; D, right palp. Scale line = 3.3 mm for A, 3 mm for B, 0.3 mm for C, 1 mm for D.

FIGURE 3. Bathyzetes umbrella sp. nov., A, oviger of paratype male; B, oviger strigilis; C, third leg of holotype male; D, detail of claw; E, tip of barbed spine. Scale line = 1 mm for A, 0.3 mm for B and D, 2 mm for C, 0.1 mm for E.

Tables

TABLE 1. Summary of main distinctions between the species of Bathyzetes.

	B. setigera	B. virago	B. extenuata	B. umbrella
chelifore scape 1: scape 2	1.25	1.7	0.7	2
cephalon: trunk segment 2	2	1	1.2	0.9
trunk: abdomen	1	1.2	0.23	1.54
trunk: proboscis	1.2	1.5	2.0	2.1
Palp article 7: article 6	2	2	4	3.25
Palp articles 8, 9, 10	Shorter than 7	Shorter than 7	Equal to 7	Longer than 7
Oviger article 5: article 4	shorter	shorter	shorter	longer
Oviger article 6: article 7	1.5	1.5	1.5	2.6