Lovenia elongata (Gray, 1845)

Arachchige, Gayashan M., Jayakody, Sevvandi, Mooi, Rich & Kroh, Andreas, 2019, Taxonomy and distribution of irregular echinoids (Echinoidea: Irregularia) from Sri Lanka, Zootaxa 4541 (1), pp. 1-100 : 83-86

Lovenia elongata (Gray, 1845)

Figures 72 , 73

1845 Spatangus elongata Gray : p. 436; pl. 6: fig. 2.

1951 Lovenia elongata (Gray) .—Mortensen: p. 97–104; pl. 7: figs. 1–10; pl. 8: fig. 1; pl. 12: fig. 5; pl. 47: figs. 10–23.

Material studied. Four denuded specimens: WUSL/EI/118, from Velvatithurai and WUSL/EI/19, EI/20, and EI/ 21, from Silavathurai, Sri Lanka.

Description.

Shape and size— Test fragile, medium-sized, 41.7–44.9 mm TL; greatest width just anterior to apical system, width 77–79% TL; test narrowing towards posterior end; outline of test nearly pear-shaped, anterior end with a very conspicuous anterior notch; oral side almost flat towards sternum, posterior end of sternum convex; greatest TH near posterior end, 37–44% TL; interambulacrum 5 forming a low keel aborally; posterior end deeply sunken, forming anal funnel; posterior end obliquely truncated in lateral view.

Apical system —Ethmolytic, with four gonopores; posterior gonopores slightly larger than anterior pair; subcentral, c. 38% TL (SD=4.3, N=4) from anterior margin; madreporite conspicuously extending beyond posterior oculars.

Ambulacra —Ambulacrum III narrow and very slightly sunken relative to other ambulacra, pore pairs small; adjoining interambulacral plates bearing two oblique, transverse series of tubercles on each plate; paired petals nearly closed with unequal poriferous zones; pores in pore pairs about equal in size, slightly pointed at inner end; posterior paired petals longer than anterior ones; adapical pore pairs rudimentary in both anterior and posterior paired petals; poriferous zones of anterior paired petals strongly unequal, posterior poriferous zones (IIa, IVb) usually 3 to 7 pore pairs and about 1.4 to 2 times longer than anterior zones (IIb, IVa); in posterior paired petals length difference not as pronounced, posterior poriferous zones (Ia, Vb) usually a single pore pair shorter than anterior ones (Ib, Va); posterior series of anterior paired petals and anterior series of posterior paired petals meet in middle of test.

Interambulacra —Aborally, large tubercles with very deeply sunken areoles present in interambulacra 1 to 4, concentrated in anterior half of test; deeply sunken areoles create prominent swelling on inside of test (so-called “ampullae”); 19–25 large tubercles present in left half, 22–28 tubercles in right half on aboral surface; aborally, 9–14 and 11–14 large tubercles in interambulacrum 1 and 2 respectively; orally large primary tubercles arranged along antero-lateral margin.

Plastron —Narrow; anterior third of sternal plates naked; labrum elongated and narrow.

Fascioles —Internal fasciole usually double or even triple at anterior end; subanal fasciole broad, bilobed and leading into anal funnel; width 37–45% TL; usually containing 6–9 pore pairs on each side; no anal branches; 7–11 and 7–9 large tubercles with deeply sunken areoles present within left and right halves of subanal fasciole respectively.

Peristome —Reniform; moderately large, length c. 10% TL, width about 17% TL; c. 25% TL from anterior margin of test.

Periproct —Length 12–19% TL, width 13–16% TL; situated in a deep invagination on posterior face of test; periproct fully visible in oral view.

Geographic range. Indo-West Pacific, from East Arabia & Madagascar ( Mortensen 1951), Red Sea ( Fourtau 1904), South East Arabia ( Mortensen 1948c), Persian Gulf (), Maldives area ( Koehler 1914), Sri Lanka ( Herdman et al. 1904), Bay of Bengal ( Koehler 1914), East Indies (de Meijere 1904), North Australia ( Clark 1938) to NSW ( Miskelly 2002), Philippine Islands ( Mortensen 1948e; Mooi & Munguia 2014), China & South Japan ( Chang & Wu 1957).

Bathymetric range. Tidal zone to 94 m ( Mortensen 1951).

Observed occurrence in Sri Lanka. Specimens were collected from Silavathurai on sand patches between patch reefs on the north-western coast (at 10 m depth) and from the Velvatithurai fish landing site, on transported and discarded by fishermen, on the northern coast of Sri Lanka. In addition, this species was observed in Trincomalee (at 3 m depth), on the eastern coast and Mulathiv, on the northern coast of Sri Lanka ( Fig. 73 ). This species was first recorded from Sri Lanka by Döderlein (1888). Bathymetric range of this species in Sri Lanka is 3–73 m.

Remarks. The aboral primary spines are usually yellowish with violet bands. This species can be easily distinguished from Nacospatangus altus by its anterior notch, the presence of four gonopores, numerous sunken primary tubercles on the oral and aboral side, the plastron without a prominent keel, and the bilobed subanal fasciole.

Figures

FIGURE 72. Lovenia elongata (WUSL/EI/119): A, aboral view; B, oral view; C lateral view (left side); D, anterior view; E, posterior view.

FIGURE 73. Distribution map of Lovenia elongata recorded in this study.