Achelia karachiensis, George & Siddiqui & George & Lucena, 2020

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 : 374-376

Achelia karachiensis sp. nov.

( Figure 3 )

urn:lsid:zoobank.org:act:B8803BE6-F3D4-4664-86AD-FCC424E99072

Material examined: Holotype. ( CEMB, PYC–012 ) 1♂, Sandspit, 28.xi.2015, on Zoanthus sansibaricus . Paratype. ( CEMB, PYC–013 ) 1♂, Sandspit, 28.xi.2015, on Zoanthus sansibaricus .

Diagnosis: Lateral processes with large “branched” tubercles, tube-like tubercles and simple tubercles with an apical spine. Abdomen with a rounded tubercle at the base. Coxa 1 with two pair of simple tubercles with an apical spine and one pair of large “branched” tubercles, each with multiple spines. Coxa 2 with two pairs of simple tubercles, each with an apical spine. Femur with a strong elongated cone-like cement gland at dorsodistal end of all legs. Auxiliary claws present.

Description: Tiny, ovoid, segmentation lines between trunk segments 1–3 vague, absent between segments 3 and 4 ( Figures 3A, B ). Lateral processes each with one large, strong, “branched” tubercle near the posterior margin and one prominent lateral tube-like tubercle, hardly visible in dorsal view. Second and third lateral processes with three tubercles, one rounded dark tubercle near anterior margin, one large, strong, “branched” tubercle and one tubelike tubercle on the lateral posterior margin. Fourth lateral processes with only one tubercle near the anterior margin. Cephalon with four tubercles, two large dorsodistal complex tubercle and two more lateral tube-like tubercles. Proboscis pyriform, robust, with half the width of the cephalic segment and nearly the same length as the trunk. Ocular tubercle short with a pointed apex. Abdomen extending to the middle of coxa 1, with a rounded tubercle at the base.

Chelifore scape with single dorsodistal spine, chela reduced, knob-like, strongly inward-bent, with one dorsal spine ( Figure 3C ), fingers absent. Palp eight-articled ( Figure 3D ), fourth article longest, last four articles are subequal, all articles have small spines. Oviger ten-articled ( Figure 3E ), fourth article longest, sixth, seventh, eighth and ninth are subequal, tenth article rounded and small, last four articles with denticulate spines, according to the formula 2:1:2:2. Eighth article with two additional long simple spines.

Legs. Coxa 1 with two pairs of simple tubercles, with an apical spine, one pair of large spiniferus tubercles with multiple spines near the distal margin ( Figure 3F ), coxa 2 with two pairs of simple tubercles with an apical spine; male gonopore at the end of a long tubercle on the ventral surface of coxa 2, coxa 3 with very small spines, femur with strong dorsodistal cement gland on all legs and few spines, tibiae subequal with long dorsal spines, smaller than those on femur, tarsus short with anterior spines, propodal heel low, four spines, sole with seven spines, main claw three-quarters of the propodus length, auxiliary claws approximately half length of main claw.

Measurements of holotype (mm): Length of trunk (measured from the anterior margin of the cephalic segment to distal margin of the lateral process 4), 0.7; trunk width (across 2nd lateral processes), 0.6; length of abdomen, 0.25; length of proboscis, 0.48; third leg – coxa 1, 0.2; coxa 2, 0.2; coxa 3, 0.15; femur, 0.32; tibia 1, 0.35; tibia 2, 0.32; tarsus, 0.08; propodus, 0.4; main claw, 0.15; auxiliary claws, 0.1.

Etymology: The word karachiensis refers to the type locality of the species, Karachi.

Type locality: Sandspit , Karachi area, Pakistan .

Remarks: The arrangement and number of tubercles on the cephalon, lateral process, and coxa 1 and 2, togeth-er with the incomplete segmentation of the trunk, are unusual in this genus. These characteristics are shared with Achelia armata Bouvier, 1916 , off the Northeast Atlantic coast. Achelia armata and A. karachiensis have almost the same number of denticulate spines on the oviger (2:1:2: 2 in present species, and 1:1:2: 2 in A. armata ), and relatively small tubercles on the femur and tibiae (when compared with the coxae). These tubercles are absent in some previously-known species from the region, like A. watumu (Müller, 1990) , or overdeveloped as in A. boschi Stock, 1992 and A. lagenari Stock, 1992 ). However, the present species has more tubercles in the dorsal region of the lateral processes and in the coxa 1 than A. armata . In addition, they are differentiated by the presence of different types of tubercles (tube-like tubercle, spiniferus tubercles and rounded dark tubercle), which are present in A. karachiensis and not described for A. armata , besides the number of heel spines, of which four can be found in the specimen and five in A. armata . These differences make Achelia karachiensis sp. nov. unique in the genus.

Distribution: Pakistan.

Figures

FIGURE 3. Achelia karachiensis sp. nov., male: (A) Dorsal view; (B) Lateral view; (C) Chelifore; (D) Palp; (E) Oviger; (F) 3rd leg. Scale bar: (A–B) 0.5 mm; (C) 0.1 mm; (D) 0.2 mm; (E) 0.1 mm; (F) 0.2 mm.