Achelia, Hodge, 1864

George, Zarish, Siddiqui, Ghazala, George, Nazish & Lucena, Rudá Amorim, 2020, A new species of Achelia (Pycnogonida: Ammotheidae) and first records of intertidal sea spiders found on Zoanthus (Cnidaria: Zoantharia) from Karachi Pakistan, Zootaxa 4821 (2), pp. 371-393 : 376

Achelia sp.

( Figure 4 )

Material examined: ( CEMB, PYC– 014) 1 juvenile, Sandspit, 28.xi.2015, on Zoanthus sansibaricus .

Description: Trunk ovate, unsegmented. Cephalon with two prominent tubercles at base of the insertion of the proboscis. Lateral processes with one small anterior and one comparatively larger posterior tubercle. Chela with seven sharp teeth. Palp 8-articulated, longer than the proboscis. Oviger not completely developed, with four articles. Coxa 1 with two pairs of spine-tipped tubercles, first pair larger than the second. Femur robust with numerous small spines, one medium sized tubercle; tibia 1 and 2 robust, with numerous small spines on the anterior margin, and a few dorsal tubercles with long and strong spines; tarsus small, with few ventral spines; propodus strong with two heel spines and four spines in the sole; main claw strong, curved, half the length of the propodus; auxiliary claw slightly shorter than the main claw.

Measurements (mm): Length of trunk (measured from the anterior margin of the cephalic segment to distal margin of the lateral process 4), 0.6; trunk width (across segment 2), 0.55; length of abdomen, 0.25; length of proboscis, 0.53; length of chelifore, 0.45; third leg – coxa 1, 0.13; coxa 2, 0.2; coxa 3, 0.13; femur, 0.35; tibia 1, 0.4; tibia 2, 0.38; tarsus, 0.08; propodus, 0.35; main claw, 0.15; auxiliary claws, 0.1.

Remarks: The present species is part of a group of species with a compact and ovate trunk, without segmentation, contiguous lateral processes and palps with eight articles. Species that share these characters are: A. sawayai Marcus, 1940 , A. adelpha Child, 1970 , A. discoidea Exline, 1936 . The ornamentation of the lateral processes and coxa 1, and structure of the palp distinguish species. The presence of two heel spines and the structure of the fourth article of the palp, with a ventral apophysis, resembles A. nana ( Loman, 1908) . However, A. nana has segmentation lines and separated lateral processes.

The absence of distinguishing characters and the immaturity of the specimen does not allow identification of this specimen.

Figures

FIGURE 4. Achelia sp., juvenile: (A) dorsal view; (B) lateral view; (C) chelifore; (D) palp; (E) oviger; (F) 3rd leg. Scale bar: (A–B) 0.5mm; (C) 0.1 mm; (D) 0.2 mm; (E) 0.1 mm; (F) 0.5 mm; detail of F 0.1 mm.