Temnopleurus toreumaticus ( Leske, 1778 )

Hegde, Mahabaleshwar R. & Rivonker, Chandrashekher U., 2013, A new record of Temnopleurus decipiens (de Meijere, 1904) (Echinoidea, Temnopleuroida, Temnopleuridae) from Indian waters, Zoosystema 35 (1), pp. 97-111 : 102-105

Temnopleurus toreumaticus ( Leske, 1778)

Cidaris toreumatica Leske, 1778: 155 , 156, tab. X.

TYPE LOCALITY. — Unknown.

MATERIAL EXAMINED. — Off Betul fishing jetty, Goa, west coast of India, 15°04’N, 73°55’E, 8-20 m depth, 20 specimens, test diameter ranges from 12.47 to 40.24 mm. Representative specimens are preserved in 70% ethanol and have been deposited as voucher samples (N = 19) at the Marine Biology Laboratory, Department of Marine Sciences, Goa University.

HABITAT AND DISTRIBUTION. — Temnopleurus toreumaticus is a fairly wide-spread species known to occur in East Africa, Madagascar, the Persian Gulf, the Red Sea and on the east coast of Australia ( Clark & Rowe 1971; Fig. 6 ). In Japan, this species is found from northern Honshu to southern Kyushu ( Mortensen 1943; Schultz 2006). Kitazawa et al. (2007) studied the habitats of this sea urchin species in Shirikiwa Bay, Japan and showed that T. toreumaticus inhabits the intertidal and subtidal zones of muddy beaches and can also be found near rocky patches with rich assemblages of algae. Published reports for Indian waters ( Ramsay 1885; Clark & Rowe 1971) suggest that this species is widely distributed and inhabits sandy and muddy substrata between 5-40 m depth.

DESCRIPTION

Test dome-shaped, rigid, well sculptured with a convex aboral surface; flattened oral surface with sunken peristome ( Fig. 2B ). HTD ranging from 12.47 to 40.24 mm (Μ = 33.92 ± 7.34 mm) and VTD from 6.68 to 25.82 mm (Μ = 20.59 ± 5.23 mm); test width about twice its height (Μ VTD/HTD ratio = 0.61:1). Test comprised of five pairs of alternately placed ambulacral and interambulacral plates, interambulacral plates placed at about the level of the ambulacral plates ( Fig. 2D ). Naked test displaying an olive green to dark grey colour ( Fig. 2D ).

Ambulacral plates compound trigeminate, their pore-pairs bearing numerous tube feet (in living specimens) and arranged in slightly vertical arcs forming a single adradial band. The single primary tubercle of each ambulacral plate close to the pore zone and surrounded by randomly scattered smaller secondary tubercles; tubercles imperforate and distinctly crenulated.

Interambulacral plates covering a slightly larger area of the test than the corresponding ambulacra. Each interambulacral plate having a central primary tubercle surrounded by smaller secondary and miliary tubercles that cover the remainder of the plate ( Fig. 5A ). Primary tubercles imperforate and distinctly crenulated. Wedge-shaped pits located at the angle of the suture, and arranged in a zig-zag manner along the middle of the interambulacrum; lateral extensions of the pits separating the interambulacral plates and reaching the pore-pair zone ( Fig. 5B ).In specimens larger than 25 mm HTD, these pits extending horizontally over the entire surface of the plate. However, sutural pits near the peristome inconspicuous ( Fig. 5C ).

The peristome is large (PSD 34.26 ± 1.87% of HTD) and roughly circular in outline with very feeble buccal notches. It is covered with soft skin and comprises of five pairs of buccal plates with buccal tube feet emanating from them. The Aristotle’s lantern is of the camarodont type (i.e., with a paired rod-like epiphysis bridging across the upper end of the pyramid ( Fig. 5D )).

Apical system dicyclic and smaller than the peristome (AD 19.86 ± 2.02 % of HTD), with four equal-sized genital plates and one larger genital plate with madreporite. Inner part of each genital plate with small tubercles, outer part naked. The number of tubercles varying with the size of the specimen: 1-2 tubercles in specimens <12 mm, whereas 3-5 tubercles in larger specimens.

Genital plate wider than long (mean GPH:GPW = 0.82:1). Gonopores roughly circular and approximately ⅓ of the genital plate’s size (GD 35.21 ± 5.98 % of GPH); located at the centre of each genital plate. Ocular plates oval-shaped and placed at the junction of two adjacent genital plates, but not reaching the periproct margin. Ocular plates covered with 3-4 small tubercles. A small depression present at the junction of the ocular plate with its two adjacent genital plates. Periproct roughly circular in outline, ∕ ₁₀ of maximum test diameter (PPD 11.40 ± 1.58 % of HTD) and composed of dark brown plates. Anal opening located near the centre of the periproct; suranal plate absent ( Fig.5E ). Spines thick, with a total length not exceeding maximum test diameter (SL 61.80 ± 11.74 % of HTD). Their surface covered with fine longitudinal ridges. Spine colouration grey with alternating greenish or brownish bands ( Fig. 4B ).

BRIEF DESCRIPTION OF OTHER SPECIES OF THE GENUS TEMNOPLEURUS

Figures

FIG. 6. — Geographical distribution of Temnopleurus decipiens (de Meijere, 1904) and Temnopleurus toreumaticus (Leske, 1778). Scale bar: 1 000 km.

FIG. 2. — A, B, oral views of Temnopleurus decipiens (de Meijere, 1904) (A) and Temnopleurus toreumaticus (Leske, 1778) (B); C, D, aboral views of T. decipiens (C) and T. toreumaticus (D). Scale bars: 10 mm.

FIG. 5. — Temnopleurus toreumaticus (Leske,1778):A, primary tubercle;B, interambulacrum;C, sutural pit near peristome;D, pyramid of Aristotle’s lantern; E, apical system. Scale bar: 10 mm.

FIG. 4. — Banding on spines of: A, Temnopleurus decipiens (de Meijere, 1904); B, Temnopleurus toreumaticus (Leske, 1778). Scale bars: 10 mm.