Callipallene distortia, 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 : 12-15

Callipallene distortia sp. nov.

Figure 5a–i. Plate 5a–h u r n:lsid:zo oba n k.org:act:8 47BE50F- 0A57- 45E A-88DB -

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Callipallene micracantha Staples 2005: 168 , fig. 5C–E.

Material examined. Holotype. Male ( SAMA E9452 ). Tasmania, 48 nm north-east of East Sister Is. , (39°04’S, 148° 39’E), depth 432 m, Epibenthic Sled, sandy bottom, W. Zeidler, CSIRO Soela stn 21, 13 October 1984.

Paratypes. Two males, one female (gravid), three juveniles ( SAMA E9453 ). Same collection details as holotype .

Diagnosis. Neck well-defined, length about equal to width. Eye tubercle with apical cone. Chelifore scapes not quite reaching proboscis tip, chela fingers of equal length, crossing at tips, gap at base of fingers, immoveable finger with about twelve well-developed teeth, moveable finger without defined teeth. Anal tubercle short, erect. Femur longer than tibia 1, widest distally and bearing several short spines, two low ventral spine-tipped swellings at about one-third and two-thirds length, far more conspicuous in the female; heel low, four or five heel spines, auxiliary claws about half length of main claw.

Description. Holotype, male. Leg span, about 16.0 mm. Trunk completely segmented. Neck short but well-defined, length about equal to width in dorsal view (fig. 5a; plate 5a); crop wide, anterior width greater than three-times width of neck, two or three small spines present at base of each chelifore implant. Length of lateral processes about 1.4 times basal width, 1–4 dorsodistal spinules variable present.

Eye tubercle with short apical, slightly forward-leaning cone, two lateral papillae at base of cone, four eyes.

Proboscis implanted obliquely onto ventrodistal surface of cephalon, ventral length about 1.8 times maximum width, distally angulate (plate 5d, h), few scattered setae. Jaws and lips protruding.

Chelifore scape reaching to about proboscis tip, few surface spines, two strong spines on inner lateral surface and distal margin. Chela palm with many setae along dorsal surface. Fingers of equal length, crossing at tips, moveable finger closing to outer side, immoveable finger with single row of about twelve short, well-developed sharp teeth, moveable finger cutting margin unclear, but may be lowly crenulate. Immoveable finger with proximal indentation creating a gap at base of fingers (fig. 5d).

Oviger (fig. 5e) ten-segmented, distal apophysis segment 5 prominent, height about equal to width of segment, 1–2 setae present, no spinules evident on lateral surface of segment, compound spines are of the form illustrated by Clark (1963, fig. 11E), compound spine formula, segments 7–10, 10:8:8:8, distal-most spine on segments 7–9 largest, more strongly curved and with a variable arrangement of lateral teeth as in C. micracantha (see Staples 2005, Fig. 5C).

Anal tubercle short, erect, few distolateral seta, basal articulation absent.

Legs (figs. 5f, plate 5e). Coxa1 fringed dorsodistally with well-developed spines, coxa 2 almost three times length of coxa 1, few spines; femur and tibia 1 widest distally, femur longer than tibia 1, bearing two ventral spine-tipped low swellings, at about one-third and two-thirds length; tibiae particularly spinous with many short spines interspaced by occasional longer spines but none particularly prominent (fig. 5f), cuticular surface minutely irregular, tibia 2 longest and of consistent width throughout, propodus (fig. 5g) evenly curved, main claw almost touching tip of distal-most heel spine when closed, about fifteen sole spines, all spines slender, pointed, smooth, heel low, four to five primary spines variably arranged, but with at least one pair of side-by-side spines present, proximal-most spine curved, smallest, auxiliary claws about one half-length of main claw, without crenulations. Gonopores small, ventrodistal, second coxa, legs 2–4. Cement glands not evident.

Measurements of holotype (mm). Trunk length (frontal margin of cephalic segment to tip of fourth lateral processes), 2.47; width across second lateral processes, 1.05; proboscis length (ventral) 0.78; greatest diameter proboscis 0.43; scape length 0.47; anal tubercle length, 0.08. Oviger: seg. 1, 0.08; seg. 2, 0.27: seg. 3, 0.31; seg. 4, 0.58; seg. 5, 1.03; seg. 6, 0.19; seg. 7, 0.27; seg. 8, 0.24; seg. 9, 0.23; seg. 10, 0.19. Third leg: coxa 1, 0.29; coxa 2, 0.83; coxa 3, 0.32; femur, 1.77; tibia 1, 1.69; tibia 2, 2.34; tarsus, 0.14; propodus, 0.66; claw, 0.36; aux claws, 0.17.

Female. Slightly larger than male (leg span about 19.0). Femur of this gravid female greatly swollen, two prominent spine-tipped ventral swellings (fig. 5i, plate 5f). Coxa 2 shorter than male, about 2.1 times length coxa 1 (versus 2.9 times). Gonopores larger than male, ventrodistal, coxa 2 all legs. Heel spines variably paired as with male (fig 5h).

Remarks. Leg spines are easily dislodged. A single row of what appear to be about eight transverse cement gland slits like those described by Stock (1954, Fig. 33) in Anoplodactylus pycnosoma Helfer, 1938 , are evident in the image of the posterior lateral surface of legs 3 and 4 (plate 5b). These slits were not however, apparent in the actual specimen when viewed through a light microscope. Low, ventral spine-tipped swellings on the male femora are more pronounced on some legs. Swellings on the female leg are more prominent, particularly on the gravid adult. The heel spine arrangement is variable but one or two pair of side-by-side spines are always present. Interestingly, Döhrn (1881) described the heel of the C. emaciata holotype as having 4–5 basal spines, two of which also stand side by side.

These South Australian specimens are best compared to C. emaciata , C. novaezealandiae and C. micracantha . Callipallene micracantha Stock, 1954 and C. novaezealandiae ( Thomson, 1884) were designated as subspecies of C. emaciata and C. brevirostris ( Johnston, 1837) before being raised to full species status by Bamber (2005: 331). This proposed new species is readily distinguished from C. emaciata by the presence of a defined neck (almost absent in C. emaciata ), a distally angulate proboscis (distally rounded in C. emaciata ), smooth heel spines and auxiliary claws, (crenulated tips of the tarsus and primary heel spines and rugosities or serrations on the auxiliary claws in C. emaciata ) and spine-tipped swellings on the surfaces of the femur and first tibia that contribute to a distorted appearance (absent in C. emaciata ).

Child (1990) recorded several specimens from Heron Island which he designated species intermediate and which agreed in almost all respects with Stock’s (1954) figures of an unnamed subspecies of C. emaciata from Three Kings Islands, New Zealand. Based primarily on the absence of any striking features, and the absence of adequate material, Child refrained from naming his specimens. Unfortunately, Child did not provide figures or comment on proboscis shape or sexual dimorphism, but presumably the legs of the Heron Island specimens shared the distorted appearance of the femur and first tibia which Stock regarded as “perhaps the most striking feature of his subspecies”. As far as I am aware, the low swellings that gave rise to the distorted appearance of the femora and tibiae have never been regarded as a characteristic of C. emaciata sensu stricto and it is not clear therefore why Stock did not place more importance on their presence. These specimens and Stock’s unnamed subspecies (and Child’s ‘species intermediate’), appear to have much in common, distinguished only by the shape of the proboscis which Stock described as “conical in its distal part”, but which is nevertheless, a significant distinction. The only published record of C. emaciata from Australian waters was by Bamber (2008: 137, Fig. 4) who assigned a single male specimen (subsequently lost) and one subadult from Moreton Bay, Queensland to C. emaciata but based on his figures and brief description, his specimens bear very little resemblance to Stock’s New Zealand subspecies. Bamber quite rightly observed that the attribution of so many records of this species from such disparate geographical areas is highly improbable.

The type locality of C. novaezealandiae is Otago Harbour, South Island, New Zealand. The present material differs from C. novaezealandiae in several respects, but perhaps most conspicuously, by the shape of the proboscis. Thomson (1884) described the proboscis of C. novaezealandiae as “stout and nearly cylindrical in form” and “narrowing abruptly to the rounded extremity” whereas the proboscis of this specimen is distinctly angulate. Other differences are found in the shape of the femora which in C. novaezealandiae are slender and without any distortion, as opposed to spine-tipped swellings found on the on the femora of specimens examined in this collection. Also, both fingers of the chelae in C. novaezealandiae bear a row of small denticles on their inner surface, versus well defined teeth on the immoveable finger only, in these specimens. The species was subsequently recorded from New Zealand by Stock (1954) who assigned two males and three females collected from three localities to C. brevirostris ssp novaezealandiae . Based on Stock’s measurements, the second coxa of the female C. novaezealandiae is over four-times the length of coxa 1 compared to a little more than two-times longer in this female paratype. Stock based his description of the male on what appear to be a combination of two morphologically dissimilar specimens and provided dorsal views only of the trunk, presumably to compliment Thompson’s ventral view. Disappointingly, Stock dismissed differences in the length of the neck to a “slight variation” and did not comment on differences in the shape of the eye tubercle which he described as lowly conical, versus short and blunt in the holotype. Thomson figured the holotype of C. novaezealandiae in ventral view only, showing no segmentation of trunk segments 3 and 4. Stock presumably attributed the absence of segmentation to immaturity, but the presence of incomplete segmentation is now a well-known characteristic of many adult species. Records of C. novaezealandiae are predominantly from New Zealand, Australia, western Pacific Islands, Japan and western Indian Ocean but with so many specimens being in close morphological agreement, I am confident that Bamber’s (2008) sentiments concerning the improbability of accurate species identification of C. emaciata , should equally apply to records of C. novaezealandiae , particularly those justified on supposed morphological variables. The growth-related variables observed by Stock (1952) are not evident in the three juvenile specimens in this collection. Australian records are predominantly from the southeast of the continent but Arango’s (2009) unlikely record of a female from Ningaloo Reef would extend the Australian range of the species into tropical waters. Child (1975) provisionally recorded a single female from south Australian waters.

These specimens share the spine tipped swellings on the ventral surface of the femur and first tibia, and the angulate distal corners of the proboscis with C. micracantha . Stock’s measurements indicate that tibia 1 of the holotype is longer than the femur but his figure ( Stock 1954, 19f) shows that the femur is longer, which matches these specimens. The obvious difference between these specimens and C. micracantha is in the shape of the neck which is well-defined and clearly independent of the crop whereas Stock described the crop of C. micracantha as “not distinctly marked from the rest of the neck” ( Stock, 1954, fig. 20a). Other differences can be summarized as follows: (1) the eye tubercle of this specimen is distinctly conical at the tip compared to Stock’s description of it being truncated with a small median tubercle in C. micracantha , (2) the immoveable finger of this specimen has one row of teeth as opposed to two rows in C. micracantha , (3) the inner margin of oviger segment 5 in these specimens lacks the lateral spinules found in C. micracantha and, (4) the propodus is more compact and more strongly curved, (compare plate 5g herein with Stock, 1954, fig. 19G). Stock did not mention the heel spine arrangement, and simply described the propodus as having four basal spines, without mention of the characteristic pairing arrangement evident in these specimens. Stock made a point of the oviger implantation in C. micracantha being large, but there is nothing remarkable with these specimens. Dorsal spinules on the lateral processes appear to be less robust than those depicted by Stock. Clark (1963 Fig. 12A–H) figured and briefly described a male specimen from Twofold Bay, New South Wales but the long auxiliary claws, long second coxa, (> 4-times the length of coxa 1) and rather straight-sided femora and first tibia, serve to distinguish that specimen from the present material.