Queubus echidna, Bamber, Roger N. & Steffani, Nina, 2007

Bamber, Roger N. & Steffani, Nina, 2007, A new species of Queubus Barnard, 1946 (Arthropoda: Pycnogonida) from Namibia, Zootaxa 1531, pp. 57-61 : 58-61

Queubus echidna sp. nov.

Figs 1 , 2 .

Material: 1 male, holotype (Registration No. NHM 2007.305), Chameis Deep, Namibia, 27º51.635’S 15º35.291’W, very coarse brown sand (0.7% silt-clay, 86.5% sand, 12.8% gravel) at 46 m depth, van Veen grab sample, 10 December 2005.

Description: in gross morphology ( Fig. 1 ) similar to Q. jamesanus . Integument finely reticulate; trunk segments naked, not raised posteriorly, without dorsal tubercles. Cephalon 43% of total body length, anterior margin with slight median cleft, and three small, stout spines to either side of cleft. Ocular tubercle very low, just anterior to mid-point of cephalon, with four pigmented eyes and pair of lateral sensory pits. Lateral processes not contiguous, separated by less than half their own width, each with a postero-distal triangular apophysis. Abdomen set off by distinct articulation from fourth trunk segment, oriented slightly downwards, clavate with rounded apex, naked.

Proboscis ( Fig 2 A) bulbous, not tapering, triradiate, carried vertically below cephalon. Attachment to cephalon via a distinct, short peduncle of same diameter as proboscis. Slight constriction in proximal third.

Chelifores absent.

Palp ( Fig 2 A, ‘P’) of two articles, naked, distal segment twice as long as proximal segment; situated below cephalon, adjacent to oviger implantation.

Oviger ( Fig 2 A, B) of ten articles, articles 1 to 6 naked. First article short, compact; second article 1.2 times as long as wide, 1.2 times as long as third article; articles 4 and 5 subequal, three times as long as article 3; article 5 longest, curved, bulbous, expanding towards distal end; article 6 half length of article 5; article 7 as long as article 3, with one ventral denticulate spine; article 8 half as long as article 7, with two ventral denticulate spines; article 9 shortest, naked; article 10 ( Fig. 2 C) 1.3 times as long as article 8 with three ventral denticulate spines, one larger distal denticulate spine opposing simple distal claw. Estimated 500 small (ca 50 μm diameter) eggs held in membrane around both ovigers.

Third leg ( Fig 1 ; 2D) coxa 1 with two postero-ventral and one dorsodistal triangular apophyses, paired mid-dorsal stout spines; coxa 2 1.5 times as long as coxa 1, naked, with minute ventrodistal gonopore; coxa 3 half length of coxa 2, naked; femur longest article, 1.24 times as long as coxa 2, sinuous, swollen ventrally, with mid-dorsal, ventral and dorsodistal stout spines; tibia 1 0.75 times as long as femur, with small dorsodistal and ventrodistal spines; tibia 2 1.2 times as long as tibia 1, with single, short anterolateral spine and three large distal blunt spines; tarsus short, naked; propodus ( Fig. 2 E) curved, without heel, with four blunt sole spines and small dorsodistal blunt spines; main claw simple, curved, 0.6 times as long as propodus; auxiliary claws absent. Cement gland not evident.

Coxa 1 of first leg with only single postero-ventral apophysis.

Measurements of holotype male (mm). – Trunk length: 2.9; trunk segment 2 length: 0.54; width across 2nd lateral processes: 1.6; abdomen length: 0.46; proboscis length: 1.85.

Lengths of oviger articles 1 to 10 respectively: 0.09; 0.23; 0.19; 0.61; 0.65; 0.32; 0.20; 0.11; 0.08; 0.14.

Fourth leg, lengths of coxa 1: 0.43; coxa 2: 0.62; coxa 3: 0.29; femur: 0.77; tibia 1: 0.55; tibia 2: 0.65; tarsus: 0.1; propodus: 0.45; main claw: 0.28.

Etymology: named after the spiny mammal, Tachyglossus aculeatus , in allusion to the stout spines on the anterior edge of the cephalon and on the leg articles, as well as after the Mother of all Monsters in Greek mythology, who had a speckled skin.

Remarks: Queubus echidna sp. nov. is similar only to Q. jamesanus , in particular in the overall body conformation, the lack of chelifores, the articulation of the abdomen, and the proportions of the oviger articles. Both species have a peculiar peduncle to the proboscis, apparently of arthrodial membrane, not known from any other pycnogonid genus (it appears not to be homologous with the proboscis peduncle found in the genus Eurycyde ). Unlike Q. jamesanus , the present species has palps, of two articles, situated below the cephalon near the oviger implantation. This palp morphology is typical of some callipallenid genera (e.g. Propallene Schimkewitsch, 1909 ) and would be expected to occur only in the male. The proboscis of the present species is also markedly different, that of Q. jamesanus being long and slender, tapering to a tube (e.g. Barnard, 1954: Fig. 34). Barnard’s species is further distinct in having a propodal heel armed with pointed spines, a distally pointed abdomen, mid-dorsal tubercles on all four trunk segments, simple spines on the oviger, and it is without the plethora of blunt spines present on the legs of Q. echidna .

The genus remains endemic to Atlantic southern Africa.

Figures

FIGURE 1. Queubus echidna sp. nov., holotype male, dorsal. Scale line = 2 mm.

FIGURE 2. Queubus echidna sp. nov., holotype male, A, cephalon, proboscis, oviger and palp (P), lateral; B, oviger; C, distal oviger article; D, third leg; E, detail of propodus and main claw. Scale line = 1 mm for A and D, 0.5 mm for B, and 0.15 mm for C and E.