Holothuria (Lessonothuria) lineata Ludwig, 1875

Ahmed, Quratulan, Thandar, Ahmed S. & Ali, Qadeer Mohammad, 2020, Holothuria (Lessonothuria) insignis Ludwig, 1875 (formally resurrected from synonymy of H. pardalis Selenka, 1867) and Holothuria (Lessonothuria) lineata Ludwig, 1875 - new additions to the sea cucumber fauna of Pakistan, with a key to the subgenus Lessonothuria Deichmann (Echinodermata: Holothuroidea), Zootaxa 4767 (2), pp. 307-318 : 314

Holothuria (Lessonothuria) lineata Ludwig, 1875

Figure 4

Holothuria lineatea Ludwig, 1875: 77–120 , pls. 6–7.

Holothuria (Lessonothuria) lineata Rowe (in Rowe & Gates, 1995): 291;? Holothuria (Lessonothuria) lineata Thandar, 2008: 53 , fig. 20; Samyn, Massin & VandenSpiegel, 2019: 81 –91, figs. 1–4.

? Holothuria (Lessonothuria) insiginis Thandar 2007:16 , text-fig. 6) (= H. (L.) lineata ).

Material examined. Buleji, Karachi, Buleji (24º 50’ 20.41’’ N, 66º 49’ 24.15’’E), Holo. 23, 23 May 2017, 1 spec.

Habitat. The specimen was found under a rock on sand in the intertidal zone, attached to some algae and seaweeds and covered with fine sand.

Description. Length about 85 mm. Body cylindrical, dorsal surface arched. Colouration of live specimen dark chocolate brown dorsally ( Figure 4A ) with ventral surface light brown with white blotches and dark streaks ( Figure 4B ). Tube feet creamy white. Dorsal body wall rough, thin. Mouth and anus terminal; anus encircled by 16 papillae. Tentacles 19, creamy white in colour. Calcareous ring well developed (4C), radial plates larger than interradial plates, almost rhomboidal, interradial plates typical, triangular with a posterior notch. Polian vesicle and stone canal damaged. Cuvierian tubules absent. Ossicles of body wall comprise tables and pseudo-buttons. Dorsal and ventral body wall tables, 33–62 µm, with usually complete, strongly spinose disc with four central and 10–12 marginal holes (4D), some discs smooth. Pseudo-buttons, 30–54 µm, usually complete with 2–5 pairs of holes but often incomplete, especially ventrally, with holes developed only on one side, rarely twisted (4E) but not knobbed. Tube feet with curved, elongated rods, 68–228 µm, with several terminal holes (up to 10) and characteristic, multilocular plates, 110–232 µm, with serrated, jagged or spiny margins and 2–3 series of holes (4G), always accompanying reduced end-plates (4I & F). Tentacle rods, 62–148 µm, slightly curved, perforated or digitated at ends (4H).

Remarks. Holothuria (Lessonothuria) lineata ( Ludwig, 1875) was not reported from the Pakistan coast before and hence it is new to the holothuroid fauna of Pakistan. The specimen is to some extent similar to those described as H. (L.) insignis by ( Thandar, 2007), who later ( Thandar 2008), after studying a juvenile of the species, referred all his materials to H. (L.) lineata . This action, as stated above needs to be re-visited. Rowe (in Rowe & Gates 1995) considered H. lineat a a valid species, although it was relegated to the synonymy of H. pardalis by numerous workers. A re-description of the species, based on type material and a specimen taken from Glorioso Islands, Mozambique, was recently published in some detail by Samyn et al. (2019) who also provide an abbreviated key to separate four related species. However, we here present a key to separate all 11 currently recognized species in the Lessonothuria group by WoRMS (accessed 10 October 2019), but all may not necessarily belong to this subgenus as some do not appear to be consubgeners as they are based on a single specimen with a couple having a bizarre combination of characters.

Figures

FIGURE 4. Holothuria (Lessonothuria) lineata Ludwig, 1875. Holo. 23. A. Ventral view; B. Dorsal view; C. Calcareous ring with tentacles; D. Tables of dorsal body wall; E. Buttons from body wall; F. End-plate from anal papillae; G. Plate from podium; H. Tentacle rods; I. Perforated rods from podia; J. Part of calcareous ring (single dorsal radial and adjoining interradial plates).