Parapallene challengeri Calman 1937

Staples, David A., 2025, Pycnogonids, ‘ sea-spiders’ (Arthropoda, Pycnogonida) selected from the collections of the South Australian Museum with descriptions of new species and review of the genus Pallenella., Memoirs of Museum Victoria 84, pp. 1-47 : 18-19

Parapallene challengeri Calman 1937

Plate 7a–f

Parapallene challengeri . — Calman 1937: 532-534, figs. 1–6. — Clark 1963: 31 [key]. — Stock 1991:193 [key]. — Staples 1997: 1057, fig. 21.4f.— Arango 2009: 8 , fig. 8B.

Material examined. One gravid female ( SAMA E9436). South Australia, Edithburgh Jetty, Yorke Peninsula, 3–4 M, on weed at night, K.L. Gowlett-Holmes, 4 Mar 1995 .

Remarks. Owing to a mix-up of specimens, the location of the female holotype is uncertain, it being either Challenger station 162 Bass Strait, or station 163 Twofold Bay, New South Wales (NSW) ( Calman 1937). There is no evidence of a “fold of cuticle” on the neck of this specimen as described by Calman but the compression of his specimen for the purpose of illustration would have distorted the length of the neck and perhaps, the relative widths between the lateral processes. The scapes bear many setae, particularly along the inner margins but are without tubercles or processes. Lateral processes 3 and 4 in this specimen are separated by about 1.5 times their own diameter, whereas Calman describes the lateral processes as being separated by not more than their own diameter. This specimen is close to that recorded by Arango (2009, Fig. 8B) from Western Australia which had lateral processes more widely spaced and with a longer neck compared to Calman’s holotype. Calman’s description of the oviger was brief and unfigured, but the spine formulae are close (holotype 6:5:5:5, this specimen 6:5:5:6). The first coxa bears one or two distal spines. Coxa 2 has a small mid-dorsal papilla placed distal to mid-length and a strong spine on the lateral surfaces. There are several strong spines around the distal margin and a large ventrodistal gonopore is present on all legs (plate 7e). A conspicuous but short, spiniferous tubercle is present on the ventrodistal surface of the third coxae.

Plate 7. P. challengeri , female ( SAMA E9436): a, b, trunk dorsal and lateral views; c, leg 3; d, propodus and tarsus leg 3; e, coxae leg 3; f, femur leg 3.

There is evidence to suggest that several spines on the lateral surfaces of each of the longer segments of the legs have been broken off. The dorsodistal surface of the femur is without a prominent tubercle but is rather swollen and with one or two strong setae. The ventral surface (plate 7f) is considerably more irregular than illustrated by Calman (1937, Fig. 5) and possibly represents what Arango (2009) described as spine-tipped “bumps or knobs”. Most spines on the femur and tibiae are finely serrated, the cuticular surfaces of both tibiae are without distortions, tibia 1 has a prominent spine-tipped dorsodistal tubercle. Most legs of this specimen have the distal segments missing, perhaps indicating forceable removable from the host substrate. Of those legs with the propodus remaining, the number of heel spines vary from 3 to 4 and sole spines vary from 3 to 6. The distal-most sole spines are crowded and smaller. The largest sole spine is about half the size of the largest heel spine and all larger spines are interspaced by smaller spines. Heel and sole spines are finely toothed or crenulate on the distal surface. The main claw and auxiliary claws are smooth. The anal tubercle is missing from this specimen. From the closely related P. australiensis ( Hoek, 1881) , P. challengeri is immediately distinguished by the presence of auxiliary claws.

Distribution. Records range from Twofold Bay, NSW to Albany Point, WA at depths ranging from 24– 220 m.