Metalia sternalis
Creators: name: Arachchige, Gayashan M.
name: Jayakody, Sevvandi
name: Mooi, Rich
name: Kroh, Andreas
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Echinoidea
Spatangoida
Brissidae
Metalia
Metalia sternalis

description: Metalia sternalis (Lamarck, 1816)
Figures 66, 67
1816 Spatangus sternalis Lamarck: p. 31.
1951 Metalia sternalis (Lamarck).—Mortensen: p. 535–537; pl. 64: figs. 13, 17, 19, 22.
Material studied. Seven denuded tests: WUSL/EI/70 and EI/71, from Baththalangunduwa 2 and WUSL/EI/122, EI/123, EI/124, EI/125, and EI/126 from Silavathurai, Sri Lanka.
Description. Shape and size —Test large, 60.6–84.5 mm TL; width 89–92% TL; height 55–59% TL; outline of test elliptical to slightly angular in aboral view, with anterior slope more steeply angled forward than the posterior slopes to the periproct; slightly truncated posteriorly; anterior notch deep and broad.
Apical system —Ethmolytic, with four large circular gonopores; posterior paired pores about 1.5 times larger than anterior ones; madreporite expanding beyond posterior oculars; situated anteriorly, 30–37% TL from anterior margin.
Ambulacra —Ambulacrum III narrow and depressed aborally; paired ambulacra distinctly petaloid, deeply sunken towards margin, broad, elongate, somewhat rounded and closed distally; anterior paired petals extend laterally forming an angle of c. 175° from each other, c. 65% of TW; petal III length c. 33% TL (SD=2.3, N=7); interporiferous zone broad, of equal width in each petal; respiratory pores large, pores within one pair about equal in size, connected by deep groove; posterior paired petals 1.25 times longer than anterior ones; adapically posterior paired petals narrow; at about one quarter petal length, inner pore pairs rudimentary; posterior paired petals coalescing, elongate, slightly diverging posteriorly; at about half petal length, two poriferous zones are equal width, up to petal tip.
Interambulacra —Aboral interambulacrum 5 raised, slightly convex to flat; but not keeled, not projecting above periproct; posterior end almost vertically truncated; interambulacra densely packed with perforate crenulate primary tubercles, larger tubercles inside peripetalous fasciole, particularly along petals; adapically no primary tubercles in interambulacrum 5 between posterior paired petals.
Fasciole —Peripetalous fasciole well-developed, closely outlining petals, with indentations between petals; subanal fasciole broad, shield-shaped, wider than long; length 26–29% TL and width 31–39% TL; left and right halves joining at point near posterior edge of plastron; five to six pore pairs inside subanal fasciole on each side; anal branches present, extending aborally to points even with adapical margin of periproct.
Plastron —Narrow, elongate, width 25–31% TL, slightly keeled.
Peristome —Kidney-shaped; very close to anterior edge, 19–27% TL from anterior margin of test; about twice as wide as long; moderately large, length 8–10% TL, width 17–19% TL; labrum narrow and wide.
Periproct —Elongate along anterior-posterior axis; pointed above and below; large, length 15–20% TL and width 8–11% TL.
Geographic range. Indo-West Pacific, from Islands of West Indian Ocean (Bell 1884), Mauritius (De Loriol 1883), East Africa & Madagascar (Mortensen 1948c), Red Sea (Fourtau 1904), India (Bell 1888), Bay of Bengal (Clark 1925a), East Indies (de Meijere 1904), North Australia (Clark 1925a) to NSW, Australia (Miskelly 2002), Philippine Islands (Mortensen 1948e; Mooi & Munguia 2014), China & South Japan (Döderlein 1885), South Pacific Islands (Agassiz 1872) and Hawaiian Islands (Agassiz 1872).
Bathymetric range. Littoral zone to 90 m (Mortensen 1951).
Observed occurrence in Sri Lanka. Specimens were collected from a sandy bottom with sea grass beds in Silavathurai and Baththalangunduwa, north-western coast of Sri Lanka, at depth range of 10–20 m (Fig. 67). This species was first recorded from Sri Lanka by Clark (1915).
Remarks. M. sternalis can be distinguished from Metalia sp. by having a coalescence between the aboralmost regions of the posterior paired petals.
description: Published as part of Arachchige, Gayashan M., Jayakody, Sevvandi, Mooi, Rich & Kroh, Andreas, 2019, Taxonomy and distribution of irregular echinoids (Echinoidea: Irregularia) from Sri Lanka, pp. 1-100 in Zootaxa 4541 (1) on pages 75-78, DOI: 10.11646/zootaxa.4541.1.1, http://zenodo.org/record/2617460