Ascorhynchus castelli (Dohrn, 1881)

Müller, Hans-Georg & Krapp, Franz, 2009, The pycnogonid fauna (Pycnogonida, Arthropoda) of the Tayrona National Park and adjoining areas on the Caribbean coast of Colombia 2319, Zootaxa 2319 (1), pp. 1-138 : 55-57

Ascorhynchus castelli (Dohrn, 1881)

Fig. 27

Barana castelli Dohrn, 1881: 123

Ascorhynchus castelli: Stock 1975: 966 (literature). Krapp & Kraeuter1976: 340. Stock 1986: 400. Arnaud 1987: 41.

Material: 5.— 5 juv., among them 1 subadult ( SMF 1112 ), coral rubble, 30 m, 18.II.1986 .

Description of subadult male: Trunk relatively robust, outline a long oval, fully segmented; all segments bearing slender thorny dorso-median tubercle; these tubercles on segments 1–3 of similar height, that on the 4 th segment lower. Crurigers separated by about their own diameter, with 1–2 dorso-distal setae based on tiny inconspicuous tubercles. Ocular process in the centre of comparatively long cephalon, twice as high as basal diameter, basal half cylindrical, distally a pointed cone which bears some short setae. Ocular process of same height as anterior 3 segmental tubercles, bearing distinctly pigmented eyes. Anterior margin of cephalon above origin of palps adorned with small conical tubercle, bearing 2 short setae. Proboscis about 2/3 of trunk length, broadest in proximal half, distally rounded. Abdomen somewhat ventrally oriented, its extremity reaching the distal margin of coxae 2 of legs 4, dorsally with some short setae.

Scape of cheliphores cylindrical, 3 times as long as broad, with dorso-median small tubercle bearing some short setae, in addition some dorso-distal and ventral short setae; fingers of cheliphores without teeth and relatively small. Palp 10-articled; 3 rd and 5 th articles elongate, but 5 th slightly shorter than 3 rd; 5 distal articles with many ventral and distal short setae; articles 6 and 8–10 of equal length; 7 th article 1.5 times as long as these. Oviger 10-articled; 4 th and 5 th articles elongate and of similar length; 4 distal articles with numerous pinnate spines, formula 13:9:6:7; terminal article with a curved distal claw.

Legs relatively robust; coxa 1 dorso-distally with low tubercle armed with seta; coxa 2 twice as long, coxa 3 1.5 times length of coxa 1; femur and tibia 1 of equal length, tibia 2 somewhat longer; femur and tibia 1 dorso-distally bearing irregularly rounded and narrow tubercle measuring about one fifth length of the corresponding articles; femur in addition with one distal and one postero-lateral tubercle; tarsus about as long as broad, with 6 short ventral setae; propodus 5 times as long as tarsus, feebly curved, sole with about 17 short setae. Main claw robust, moderately curved, 2/5 length of propodus.

Measurements: Length 3.0; width 1.29 (at the level of 2 nd crurigers); length of abdomen 0.86; length of proboscis 2.14; length of cheliphores 0.71. Leg 3: coxa 1. 0.53; coxa 2, 0.78; coxa 3, 0.5; femur 1.71; tibia 1, 1.75; tibia 2, 1.93; tarsus 0.24; propodus 1.31; terminal claw 0.53.

Small, juvenile specimen: Propodus nearly cylindrical. Ocular process distinctly higher than the pointed dorso-median outgrowths, each of which bearing one antero-distal seta.

Remarks: Compared to the Santa Marta material, Stock’s (1975a: 967, Fig.4 ) figures show shorter and distally rounded dorso-median outgrowths. A similar variability of dorsomedian outgrowths was also seen in Ascorhynchus castellioides Stock, 1957 (see below). Stock (1975a: 968) records a depth range of 0– 40m.

Distribution: Mediterranean and western Atlantic, from the coast of North America ( Georgia) southward to Colombia ( Arnaud 1987: 41; Stock 1975a: 966). The species was found by the VELERO III- expedition on the Caribbean coast of Colombia (Cabo de la Vela).

Figures

FIGURE 4. Achelia sawayai Marcus, 1940. A, male dorsal, B, male dorsal, C, female dorsal, D, female dorsal, E, male lateral, F, male cheliphore, G, male palp.

FIGURE 27. Ascorhynchus castelli (Dohrn, 1881): A male dorsal, B male male lateral, C juvenile lateral, D male cheliphore, E male palp, F male oviger (inset foliose spine from article 9), G male leg 3, H propodus of male leg 3.