Peronella lesueuri ( L. Agassiz, 1841 )

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 : 50-51

Peronella lesueuri ( L. Agassiz, 1841)

Figures 42–44

1841 Laganum Lesueuri Val. L. Agassiz : p. 116; pl. 24: figs. 3–6. 1948 b Peronella Lesueuri (Valenciennes) .—Mortensen: p. 263–269; pl. 47: figs. 1–4, 6, 7; pl. 48: figs. 1, 2; pl. 50: figs. 4–11; pl. 72: figs. 2, 3.

Material studied. Three denuded tests: WUSL/EI/33, EI/34 and EI/35, from Chaddy Beach, Jaffna.

Description. Shape and size —Test decagonal to elongate, medium-sized, 36.8–40.6 mm TL, longer than broad, width 90–96% TL, greatest width coinciding with tips of anterior paired petals; height 14–18% TL; oral side flat; edge slightly thickened, test raised toward centre.

Apical system —Subcentral, c. 52% TL away from anterior margin; with four circular gonopores, hydropores scattered throughout madreporic plate.

Ambulacra —Petaloid area broad, more than half TL, 59–64% TL, slightly elevated; petals broad, closed distally; petal III slightly longer than others, c. 30% TL (SD=2); anterior paired petals shortest, c. 26% TL (SD=1); posterior paired petals little shorter than petal III, c. 28% TL (SD=1); petal widths and width of interporiferous zones of all petals similar, c. 13% TL and 8% TL, respectively; width of interporiferous zone of petal III c. 9% TL; ratio between petal width and petal length 0.4–0.5; furrow connecting pores deep and sharply limited; food grooves simple and unbranched, short and inconspicuous.

Interambulacra —Slightly inflated adapically between petals; densely packed with small primary tubercles; on oral side, interambulacra forming narrow, straight bands separating broad ambulacra.

Tuberculation —Primary tubercles on oral side slightly larger than aboral ones; on oral side, glassy tubercles distributed equally even near peristome, at margin less densely; on aboral side glassy tubercles found only along margin, and are small relative to those on oral surface.

Peristome —Small, 6–8% TL, rounded to pentagonal, width c. 7% TL; situated slightly anterior of centre, c. 47% TL away from anterior margin.

Periproct —Small, 5% TL; rounded to irregular in outline on oral surface, c. 10% TL away from posterior margin; bounded by second and third postbasicoronal interambulacral plates.

Internal buttressing —Well-developed and complicated, most abundant and branched close to margin, radiating inwards along ambulacrum ( Fig. 43 ).

Geographic range. Indo-West Pacific, from the West India & Pakistan ( Koehler 1922), Maldives area ( Koehler 1922), Sri Lanka ( Koehler 1922), Bay of Bengal ( Brown 1910b), East Indies ( Clark 1925a; Mortensen 1948d), North Australia ( Clark 1938) to Hervey Bay ( Miskelly 2002), China & South Japan ( Mortensen 1948b) and Philippine Islands ( Clark 1914; Mortensen 1948e).

Bathymetric range. Littoral to 70 m ( Mortensen 1948b).

Observed occurrence in Sri Lanka. Denuded tests only were found on the beach of Chaddy Beach, Jaffna northern coast of Sri Lanka ( Fig. 44 ).

Remarks. Sri Lankan P. lesueuri is similar to Peronella lesueuri gadiana Mortensen, 1948 . According to Mortensen (1948b: 270), P. lesueuri gadiana differs from typical P. lesueuri “mainly in the tuberculation of the pore-zones, the series of miliary tubercles being interrupted by some primary tubercles”. However, this character could not be observed in the examined materials as the petaloid area was poorly preserved. Gonopores were absent in a specimen 39.8 mm TL (WUSL/EI/33).

Figures

FIGURE 42. Peronella lesueuri (WUSL/EI/33): A, aboral view; B, oral view; C, lateral view, right side.

FIGURE 43. Internal buttressing of Peronella lesueuri (WUSL/EI/35).

FIGURE 44. Distribution map of Peronella lesueuri recorded in this study.