Parapallene gowlettae, Staples, 2007

Staples, David A., 2007, Pycnogonids (Arthropoda: Pycnogonida) from the Great Australian Bight, southern Australia, with description of two new species., Memoirs of Museum Victoria 64, pp. 95-101 : 97

Parapallene gowlettae sp. nov.

Figure 1A–I

Material examined. Holotype: Elliston, in algae, S. A. Shepherd, 26 Feb 1978. SAM E3678 (1 female).

Diagnosis. Trunk slightly arched, smooth, fully segmented. Chelifore scape with prominent dorsodistal process. Ovigers 10-segmented, segments 5–7 lying parallel to segments 1–4, terminal claw divided into 5 finger-like processes. Femur with long distal process about one-third length of the segment, tarsus short, propodus strongly curved.

Description. Female holotype. Leg span about 35 mm. Trunk smooth, segmented, lateral processes 2 and 3 separated by about 1.3 times own basal diameters, lateral processes 1–3 separated from trunk by thin cuticular line, segment 4 divided dorsally by longitudinal cuticular line, posterior to the abdomen and extending ventrally, to the anterior margin of trunk segment 4; cephalon neck angled downwards from ocular tubercle, expanding distally. Ocular tubercle conical, positioned over anterior margin of 1st lateral processes, 2 sensory organs prominent; 4 eyes lightly pigmented in preserved specimen. Abdomen curved, fusiform, positioned on dorsal surface of segment 4, short, erect, not visible from ventral aspect, strongly cleft, small papillae either side of anal slit. Proboscis short, attached to ventrodistal surface of cephalon, basal region barrel-shaped with tiny spines on ventral surface, strongly constricted prior to inflated oral region, oral surface bearing numerous tiny spines, lips protruding. Chelifore scape with prominent dorsodistal process bearing scattered spinules, inner surface with few spines; chela palm almost oblong, inflated, with numerous small, scattered spinules; fingers short, off-set from distal margin of palm, moveable finger longest, with tiny, but well-defined crenulations distally. Ovigers 10-segmented, attached to ventrolateral surfaces of neck, immediately below the anterior margin of the 1st lateral processes; segments 5–7 folded back, lying parallel with segments 1–4, strigilis resting beneath basal segments; segment 1 longer than segment 2, segment 3 significantly swollen, more-so on the outside surface, separated from segment 4 by faint suture line, segments 5 and 6 each with a small dorsodistal swelling, segments 7–10 with 2 long, strongly curved ventral spines and 4 smaller dorsal spines; terminal claw about 1.3 times as long as segment 9, without crenulations or serrations, distally, the claw divides into 5 pointed finger-like processes, one of which is bifurcate. The 2nd leg is the only intact, complete leg and is used for measurements: coxa 2, 1.2 times length of coxa 1; femur having a long, distal process almost equal to one-third the length of entire segment and more or less continuous with the median line of the femur, numerous small setae distally; tibia 1 slightly curved, with similar but shorter dorsodistal process, shorter than femur or tibia 2; tibia 2 more slender than tibia 1; tarsus short; propodus curved, extended distally, overreaching base of claw; heel variably defined but not prominent, bearing 3–4 strong spines, distal spine longest; sole armed with about 5 strong spines in mid-region accompanied by smaller lateral spines, all spines finely crenulated. Genital pores large, placed on swollen ventrodistal surface of coxa 2 in all legs.

Measurements of holotype (mm): trunk length (frontal margin of cephalon to tip of 4th lateral process), 7.40; width (across second lateral processes), 2.85; proboscis length (ventral), 1.64; 2nd leg; coxa 1, 0.88; coxa 2, 1.38; coxa 3, 0.73; femur, 3.7; tibia 1, 2.13; tibia 2, 5.20; tarsus, 0.13; propodus,1.90; claw, 0.70.

Etymology. Named for Karen Gowlett-Holmes in recognition of her collecting and astute observations of the southern Australian pycnogonid fauna.

Remarks. The exoskeleton of this specimen is partially transparent, revealing a fibrous and diverticulate network of underlying tissue or cuticle. If this feature is evident in live material, it will prove to be a useful diagnostic character. The swollen oviger segment 3 is reminiscent of the similarly swollen segment 6 in several species of Endeis ( Staples, 1982: 461) .

Three species share a distal process on the femur and tibia 1: Parapallene avida Stock, 1973 ; P. famelica Flynn, 1929 and P. haddoni Carpenter, 1892 . In all 3 species the distal femoral processes are much shorter than in P. gowlettae and none share the pointed, finger-like processes on the oviger claw. Parapallene avida can further be distinguished by the shape of the chelifores and spination of the leg segments; the lateral processes of P. famelica (non Clark, 1963) are separated by about 4 times their own width and Parapallene haddoni has a much longer abdomen.

Figures

Figure 1 Parapallene gowlettae sp. nov. female holotype (SAM E3678): A, trunk, dorsal; B, trunk, lateral; C, cephalon, ventral; D, oviger segments 3 and 4; E, oviger; F, leg 1; G, coxae; H, propodus, leg 3; I, chela.