Endeis saxa, 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 : 9-11

Endeis saxa sp. nov.

Figure 4a–i. Plate 4a–f u r n:l si d:z o o b a n k.o r g:a c t:17 D2 219 9-14B7- 4 4D7-B8 43 -

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Material examined. Holotype, egg-bearing male ( SAMA E9440 ). Coffin Bay , under rocks at low tide, S. Edmonds, 6 Jan 1966.

Paratypes. Four males (one egg-bearing), nine females (three gravid) ( SAMA E9441 ). Same collection data as holotype .

Diagnosis. Lateral processes separated by about 1.7 times basal width. Eye tubercle conical. Palps not present. Anal tubercle tall, erect, height greater than 2.5 times basal width, twice length of fourth lateral processes. Length of proboscis about equal to half-trunk length. Femur with single row of about 25 lateral cement gland pores on posterior surface. Propodal heel low, three to five strong spines followed by several smaller spines, auxiliary claws about half-length main claw.

Description. Holotype, male. Leg span about 19.0 mm. Arthrodial membrane on all segments much darker than adjoining cuticle. Cephalon with two distinct, teardrop-shaped collars on anterior margin, outer surface of collars slightly bulging, several minute spines present; two tiny spine-tipped tubercles on the median surface proximal to the bases of the collars (fig. 4a, b). All surfaces with sparse and hardly perceptible spinules. Length lateral process about 1.5 times basal diameter, first pair inclined upwards and forward, processes 2 and 3 separated by about 1.7 times basal width. Each lateral process with tiny, dorsodistal tubercle.

Eye tubercle placed in line with anterior margin of first lateral processes, conical, strongly tapered distally, four eyes, two lateral papillae placed about level with top of eyes.

Proboscis swollen prior to mid-region, many distal spinules, length (measured ventrally) almost three-times maximum width and about equal to half-trunk length,

Oviger 7-segmented, placed between and in contact with collar and first lateral processes (fig. 4a, c), bases directed downward, segment 2 longest, few simple spines, segment 7 short, rounded, partly recessed into distal part of segment 6 (fig. 4e), segment 7 with several very short, blunt terminal spines, segment 6 not excessively inflated, without lobe, inner surface with two tiny compound spines, each with trifurcate tip.

Anal tubercle upright, slightly bulbous before tapering to tip, much longer than fourth lateral process, height greater than 2.5 times basal width, few tiny distal spines, pair of small but robust tubercles either side of anal opening.

Legs (fig. 4f) slender, spines short, sparse. Coxa 1 with tiny dorsomedian tubercle matching that on lateral process and accompanied by several short spines, coxae 2 and 3 with spine-tipped ventrodistal swelling, coxa 2 about three-times length coxa 1, with low dorsal papilla at about mid-length; femur longest segment, slightly enlarged distally, mild distortion in mid-region, particularly evident in dorsal view (fig. 4h), single tiny spine on each of the raised lateral surfaces, dorsodistal surface bearing one strong median spine and a smaller, more-proximal spine at its base, spine-tipped processes present either side of the main median spine (fig 4i), smaller spines also present around distal margin, about 25 femoral cement glands on posterolateral surface, mostly in a single row (fig. 4f), glands appear to open on a low swelling; tibia 1 shorter than either femur or tibia 2, widest distally, with strong dorsodistal spine, tibia 2 next longest, marginally shorter than femur, with longer fine subterminal spine about twice length of other spines; tarsus with one strong ventrodistal spine flanked by several smaller spines; propodal heel low, four to five main linear spines, third spine longest, followed by two smaller spines and several fine lateral spines, propodus curved, sole with five or six small, but robust, median spines accompanied by slender lateral spines, auxiliary claws about half-length main claw. Cuticular lateral line present on all longer segments. Small ventrodistal gonopore present legs 2, 3 and 4.

Female larger and more robust than male, ovigers absent.

Gonopores ventrodistal, coxa 2, all legs.

Measurements of holotype (mm). Trunk length (frontal margin of cephalic segment to tip of fourth lateral processes), 2.75; width across second lateral processes, 1.20; proboscis length (ventral), 1.37; proboscis greatest diameter; 0.42; anal tubercle length 0.59; length fourth lateral processes 0.29; oviger: seg. 1, 0.24; seg. 2, 0.57: seg. 3, 0.26; seg. 4, 0.36; seg. 5; 0.36; seg. 6, 0.25; seg. 7, 0.10; fourth leg: coxa 1, 0.30; coxa 2, 0.96; coxa 3, 0.40; femur, 2.32; tibia 1, 1.83; tibia 2, 2.24; tarsus, 0.12; propodus, 0.91; claw, 0.47, aux claws 0.24.

Etymology. From the Latin saxa , (rocks), referencing collection of the specimen from under rocks.

Remarks. The finding of this specimen “beneath rocks” is unusual in a genus where specimens are most often encountered amongst algae. In a few instances, the proboscis is extended, revealing a wide arthrodial membrane that adds about 10% to the extent of the proboscis. Based on the material at hand, the proboscis is capable of a near vertical, downward orientation. Femoral cement glands are present on all legs. The holotype carries eggs in a ball on each oviger (plate 4f) rather than in a single mass wrapped around both ovigers as described for E. straughani Clark, 1970 ( Staples 1982). The propodal spine arrangement varies slightly between specimens.

Only the predominantly Atlantic Ocean and Mediterranean species E. spinosa (Montagu, 1808) , shares a similar prominent anal tubercle with this species. In E. spinosa however, the anal tubercle is shorter (little more than twice basal width versus almost three times in E. saxa ). Based on Child’s figures of E. spinosa ( Child 1992, Fig. 26A–C), other differences can be summarized as follows: the proboscis of E. spinosa is more slender (length almost 4-times maximum width versus 3.3-times in E. saxa ), the lateral processes of E. spinosa are more widely spaced, the tubercles on the lateral processes are far more prominent, and the femoral cement glands in E. spinosa are located on the ventral surface opposed to the lateral surface in E. saxa ).