Fibularia ovulum Lamarck, 1816

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 : 37-38

Fibularia ovulum Lamarck, 1816

Figures 27 , 28–31

1816 Fibularia ovulum Lamarck : p. 17.

1948b Fibularia ovulum Lamarck. —Mortensen: p. 208–212; pl. 46: figs. 48–50, 21–24.

Ambulacra —Petaloid area 61–74% TL, petaloid width 42–51% TL; petals short, with 4–7 pore pairs in each series of petal III and posterior paired petals, 3–5 pore pairs in each series of anterior paired petals; pores small rounded, petals broad, open distally; pore series slightly diverging; interporiferous zones smaller than poriferous zones.

Peristome —Moderate in size, diameter 17–21% TL; rounded pentagonal, width 12–17% TL, situated slightly anterior of centre, 37–42% TL from anterior margin of test.

Periproct —Small, 9–13% TL; squarish in outline; slightly elongate, width, 8–11% TL; situated closer to peristome than posterior edge, 17–26% TL from posterior margin of test.

Geographic range. Indo-West Pacific, from the Red Sea ( Clark 1925a; Mortensen 1948c) to Coral Sea ( Miskelly 2002) and the Philippines ( Mortensen 1948b).

Bathymetric range. Intertidal zone to 385 m ( Mortensen 1948b).

Observed occurrence in Sri Lanka. Denuded tests only were found on the beach of Hiriketiya Bay, southern coast of Sri Lanka ( Fig. 27 ).

Remarks. Fibularia ovulum differs from Fibularia sp. in having a higher test ( Fig. 30 ). Test height of Sri Lankan Fibularia ovulum is relatively low compared to specimens from the Maldives. However, the total petaloid pore pair number overlaps with that of with Fibularia sp. ( Fig. 31 ).

Figures

FIGURE 27. Distribution map of Echinocyamus megapetalus, Fibularia ovulum and Fibularia sp. recorded in this study.

FIGURE 30. Comparison of test height of Fibularia ovulum (A, WUSL/EI/178) and Fibularia sp. (B, WUSL/EI/164).

FIGURE 31. Scatter plot of total pore pairs vs. test length for the material attributed to Fibularia ovulum (n=8) and Fibularia sp. (n=11).