Pallenella georgia, Staples, 2025

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 : 39-42

Pallenella georgia sp. nov.

Figure 13a–h. Plate 15a–h u r n:lsid:zooba n k.org:act:B3A8C5F2-CA4F-4 4C4-A B58 -

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Material examined. Holotype. Ovigerous male ( SAMA E9443 ). Boston I., Kangaroo Reef, off Maria Point, 34° 42´S, 135° 56´E, large boulders, reef rubble, kelp, sparse Posidonia , 3–8 m, W. Zeidler and K. Gowlett-Holmes, 17 Feb 1988.

Paratype. One ovigerous male ( SAMA E9444 ). Same collection details as holotype .

Diagnosis. Cephalon pre-ocular surface flat, cuticular division absent. Neck short, defined in dorsal and lateral views. Trunk segments not inflated dorsally, lateral processes 3 and 4 separated by about half basal diameter. Chela fingers slender, pointed, cutting edges with proximal raised areas but without defined lobes. Eight eye lenses. Heel prominent, primary spines linear, with one or two lesser, but nevertheless strong, spines on the margins; sole with about twelve spines plus many smaller marginal spines. Legs slender. Anal tubercle horizontal.

Figure 13. Pallenella georgia sp. nov., male, holotype (SAMA E9443): a, b trunk, dorsal and anterior; d, right chela; g, h, right oviger and claw. Paratype, male: c, trunk lateral; e, f, leg 3 tarsus and propodus.

Description. Leg span about 29.0 mm. Trunk (plate 15a) glabrous, lateral processes 3 and 4 separated by half own diameter or less, length one-third longer than basal width. Cephalon smooth, pre-ocular surface not mounded, without median cuticular division; neck short, defined in dorsal and lateral views, length slightly less than width (plate 15g).

Eye tubercle low, width greater than height, eight lenses, two dorsal papillae (plate 15h).

Proboscis length 2.3 times greatest width, margins of proximal half almost parallel, slightly dilating distally before narrowing to tip, jaws lined with tiny setae. The distal-most inflated part of the proboscis is accentuated by a dorsomedian blister-like swelling (fig. 13b).

Chela fingers slender, pointed, moveable finger marginally shortest, chitinous cutting edges, translucent, striated, margin of cutting edge of moveable finger slightly raised proximally, Plate 15. Pallenella georgia sp. nov., male, holotype ( SAMA E9443 ): a, trunk, dorsal; b, chelae; c, leg 3; d, propodus. Paratype ( SAMA E9444 ): e, trunk lateral showing egg mass; f. attached protonymphon; g, anterior view; h, eye tubercle anterior view .

gap between cutting edges increasing proximally creating a wide gap at bases when closed (plate 15b).

Oviger typical of males in the genus, segment 5 longest with distal apophysis, compound spine formula, segments 7–10, 14:10:9:8 (41 spines), proximal and distal spines offset from median row, terminal claw rounded at tip, fringed by well-defined, sharp teeth on both distal margins.

Anal tubercle horizontal short, inflated.

Legs sparsely spinous, spines tiny, each placed centrally on rounded mound surrounded by pale cuticle (plate 15c). Coxa 2 dorsal surface finely rugose, length about 3.5 times coxa 1, femur weakly bowed, tarsus with single, prominent ventrodistal spine flanked and preceded by many lesser spines, propodus rather slender, length about 3.3 times width measured at base of heel, curved, heel well-developed, about six primary spines arranged linearly, second spine largest, distal three spines smaller, one or two similar lateral spines, sole slender, gently curved, about fifteen spines, claw slender, both margins almost evenly curved, reaching to about mid-heel when closed. Gonopores ventrodistal, second coxae legs 3 and 4.

Measurements of holotype (mm). Trunk length (frontal margin of cephalic segment to tip of fourth lateral process), 3.34; width across second lateral processes, 1.71; proboscis length (dorsal), 1.10; greatest diameter proboscis, 0.47; scape length; 0.98; anal tubercle length, 0.28. Oviger (segs 2–10): seg 2. 0.36; seg. 3, 0.40; seg. 4, 0.98; seg. 5, 1.49; seg. 6, 0.34; seg. 7, 0.44; seg. 8, 0.32; seg. 9, 0.32; seg. 10, 0.30; claw, 0.20. Leg 3: coxa 1, 0.47; coxa 2, 1.63; coxa 3, 0.61; femur, 3.22; tibia 1, 2.83; tibia 2, 3.77; tarsus, 0.06; propodus, 0.75; claw, 0.51.

Etymology. Named for my granddaughter, Georgia Hope.

Remarks. Both specimens carry eggs attached to oviger segments 3, 4 and 5. Those on the paratype are white and similar to cotton wool balls accompanied by protonymphon (plate 15e, g) whereas those of the holotype brown and smooth (plate 15a). A number epibionts of unknown origin are present ventrally on both specimens (plate 15e). A fringe of minute setae on the proboscis is best seen by back-lighting but may cover the entire distal surface.

This species belongs to a group of six that share: (1) the absence of a mid-dorsal cuticular division, (2) a pre-ocular surface that is either low or absent, (3) chelifore fingers that are slender and pointed, and (4) a horizontal anal tubercle. These species are: P. baroni , P. chevron , P. constricta , P. difficile , P. flava and P. chevron . Only P. constricta in this group shares a combination of a pronounced propodal heel and linear spines with this species. From P. constricta , this species is distinguished most notably by the shape of the proboscis ( P. constricta with strong mid-constriction and bulbous distal part versus sides almost parallel with slight distal inflation in this species), in the number of oviger compound spines (30 in P. constricta versus 41 in this species) and in the shape of the propodal claw ( P. constricta claw broad, inner margin straight with curved tip, versus claw slender with both margins curved similarly in this species).