Pallenella brenneisi, 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 : 24-27

Pallenella brenneisi sp. nov.

Figure 7a–g. Plate 9a–h.

urn:lsid:zoobank.org:act:0DC4430F-FC5C- 47DC-8E7C-

18485F701170

Material examined. Holotype. Gravid female ( SAMA E9447 ). Coffin Bay, Gallipoli Beach, between Farm Beach and The Frenchman, (34° 28´S, 135° 19´E), on orange flexible bryozoan, 8m, N. Holmes, 24 Apr 1994.

Paratype. One gravid female ( SAMA E9450 ) same collection details .

Diagnosis. Anal tubercle horizontal. Lateral processes narrowly, but distinctly separated. Trunk segments mildly inflated dorsally, pre-ocular surface of cephalon inflated, rounded, without median elevation or defined cuticular division, base of eye tubercle forms a continuum with the base of the swollen crop, neck not defined in lateral view, short in dorsal view. Eight eye lenses. Chela robust, moveable finger strongly curved, cutting edges heavily chitinized. Legs without irregularities, covered in tiny spine-tipped papillae, tibiae 2 much wider than propodus, propodal heel prominent, well-defined, sloping to diverging sole, about thirteen primary heel spines accompanied by many smaller lateral spines, about ten sole spines also with many smaller lateral spines, claw slender, equally curved both margins.

Description. Holotype, female. Leg span about 25.0 mm. Trunk (fig. 7a, b) fully segmented, glabrous, segments mildly inflated dorsodistally, cephalon smooth, crop inflated, pre-ocular surface inflated, without median mound or mid-dorsal cuticular division, neck minimal in dorsal view, not defined in lateral view, anterior margin of eye tubercle forms a continuum with base of swollen crop (plate 9b). Lateral processes narrowly but distinctly separated, each about 1.5 times longer than basal width.

Eye tubercle wider than tall, two dorsal papillae, eight eye lenses (plate. 9a, c).

Figure 7. Pallenella brenneisi sp. nov., female, holotype (SAMA E9447): a–c, trunk, dorsal, anterior and lateral; d, left chela; e, right oviger. Paratype (SAMA E9450) f, leg 3; g, propodus of detached leg.

Proboscis with no constrictions in dorsal view, margins slightly inflated before narrowing to tip, prominent swelling evident in mid-ventral region best seen in lateral view (plate 9b), length about twice maximum width, distal one-third narrowing to tip, jaws well-defined, relatively long when compared to most species, very short fringing setae.

Chelifore scape glabrous with proximal constriction (plate 9b), chelae robust, palm swollen, minute setae around margins, fingers of equal length, about one-half length of palm, gaping for most of length when closed, fingertips blunt, closing scissorlike, with moveable finger to inner side, outer surface of immoveable finger with slight proximal swelling and barely curved, moveable finger strongly curved, without conspicuous gaps or protuberances (plate 9d).

Plate 9. Pallenella brenneisi sp. nov., female holotype ( SAMA E9447 ): a–c, trunk dorsal, lateral view and anterior views; d, chelae; e. section of leg surface showing spination: f, propodus leg 3; g, gonopore. Paratype, female SAMA E9450: h, anterior view, showing leg markings .

Oviger bases not in contact with first pair of lateral processes, directed backwards beneath first lateral processes (plate 9b, c), segment 5 longest, segment 4 next longest, with small cone at less than half segment length, terminal claw rounded distally, with short blunt teeth along both distal margins. Compound spine formula, segments 7–10, 17:10: 9: 9 (45 spines).

Anal tubercle horizontal, not reaching distal margin of fourth lateral processes, barrel-shaped, strongly constricted distally, margins of anal slit prominent, conspicuously gaping (plate 9a).

Legs without irregularities, covered in tiny spine-bearing papillae, each papilla with either an apical or outwardly facing dorsolateral spinule (plate 9e). Coxa 2 about 2.9 times length coxa 1 and about 2.3 times coxa 3, femora swollen with oocytes for most of length, narrowing distally to same width as first tibiae, tibia 2 longest segment and much wider than propodus, tarsus short, ventral surface with 2–3 longer distal spines, dense covering of smaller more proximal spines, propodus evenly curved dorsally (plate 9f), heel raised, distal surface sloping to sole, random grouping of about twelve robust heel spines of about equal size, many smaller lateral spines; sole with a marked point of divergence at base of heel, almost straight, about nineteen short, but robust spines, claw slender, both margins equally curved, reaching to proximal half of heel when closed. Cuticular lateral line extending from coxa 2 to tarsus. Gonopores conspicuous (plate 9g), ventrodistal, coxae 2, all legs.

Measurements of holotype (mm). Trunk length (frontal margin of cephalic segment to tip of fourth lateral processes), 3.47; width across 2 nd lateral processes; 1.77; proboscis length (dorsal), 1.43; greatest diameter proboscis, 0.67; anal tubercle length. 0.45. Oviger (segs 2–10): seg. 2, 0.17: seg. 3, 0.35; seg. 4, 0.63; seg. 5, 0.75; seg. 6, 0.24; seg. 7, 0.48; seg. 8, 0.24; seg. 9, 0.32: seg. 10, 0.25; claw, 0.16. Leg 3 coxa 1, 0.42; coxa 2, 1.20; coxa 3, 0.53; femur, 2.94; tibia 1, 2.36; tibia 2, 3.30; tarsus 0.10; propodus, 0.77; claw, 0.63.

Etymology. Named for Georg Brenneis in recognition of his outstanding contributions to the advancement of pycnogonid physiology, particularly his significant contribution to the taxonomic knowledge of the genus Pallenella .

Remarks. Some legs of the paratype exhibit up to four, mostly reddish, transverse bands that appear to be shadows of internal diverticula rather than remnants of surface markings. These are most evident in ventral view (plate 9h). The heels of the paratype are slightly more prominent than those of holotype.

This species shares the presence of eight eye lenses, clustered heel spines, and a significant divergence of the propodal heel and sole with P. octolentium sp. nov. It is distinguished from that species by a lower propodal heel that slopes into the sole (heel is stand-alone and clearly separated from the sole by the absence of spines in P. octolentium ), the narrower propodal claw with inner and outer margins about equally curved (claw wide, outer margin inflated in P. octolentium ), the presence of dense spine-tipped papillae on the leg surfaces (leg surfaces smooth in P. octolentium ) and having a lesser number of oviger compound spines ( P. brenneisi 45 spines versus ~ 63 in P. octolentium ). Pallenella brenneisi also shares characters with P. brevicephela but differs from that species in having a less prominent pre-ocular dorsal surface with a less defined median division line, a greater number of oviger strigilis spines ( P. brevicephala holotype 29 spines brenneisi 45 spines) and more robust chelae with shorter more strongly curved fingers.