Chromodoris quadricolor ( Rueppell & Leuckart, 1830)

Yonow, Nathalie, 2012, Opisthobranchs from the western Indian Ocean, with descriptions of two new species and ten new records (Mollusca, Gastropoda), ZooKeys 197, pp. 1-130 : 33

Chromodoris quadricolor ( Rueppell & Leuckart, 1830)

Doris quadricolor Rüppell & Leuckart, 1830: 31, pl. 9 (Red Sea).

Chromodoris quadricolor . - Rudman 1977: 370, pl. 1B, figs. 19, 20 (Tanzania); Yonow 1989: 296, pl. 8 (Red Sea); Yonow et al. 2002: 852 (part), fig. 11f only (Chagos); Debelius and Kuiter 2007: 166 (Red Sea); Yonow 2008: 176 (Red Sea).

non Chromodoris quadricolor . - Yonow et al. 2002: 852 (part), figs. 11e, 12A, B (Chagos) [= Chromodoris elisabethina Bergh].

Material.

Socotra: 20 × 9 mm pres. (St-190, F-59), Abd al-Kuri, Khaisat en Naum, western tip, 10 April 1999, leg. U Zajonz.

Description.

There are no photographs accompanying the Socotra specimen, but the preserved specimen is semi-relaxed (examined 2009), with dark orange rhinophores and gills. The mantle is black with two white stripes fading to cream with a faint orange tinge on the dorsum. There is a relatively broad white band between the black dorsum and the orange marginal band (cf. Chromodoris hamiltoni above, which normally does not have this white separation, and Chromodoris elisabethina Bergh, which has a fine white line). The white line at the very edge of the margin can still be seen (cf. Chromodoris africana p. 34 which does not have this white line). There are two black stripes on the sides of the foot, and the foot retains an orange margin. The preserved specimen is identical to specimens collected from the Red Sea in 1990: Chromodoris quadricolor appears to hold its colour extremely well in formaldehyde.

Remarks/Distribution.

Originally described from the Red Sea, its presence in Socotra is not unexpected: Rudman (1977) had specimens from Tanzania and Yonow et al. (2002) subsequently reported specimens from Chagos. Yonow et al (2002) discussed the similarities with Chromodoris elisabethina : five specimens from that collection were correctly attributed to Chromodoris quadricolor (Chag96/42, 96/51, 96/52a, 96/52b, 96/52c, and 96/87, colour figure 11f); however, two specimens are here reassigned to Chromodoris elisabethina (Chag96/16 and 96/87, colour figure 11e, and radular preparation, fig. 12a, b). Re-examination of the specimens and additional colour slides revealed that these animals both had darker patches located centrally as well as behind the rhinophores, clearly visible in the figure of specimen Chag96/87e in Yonow et al. 2002 (fig. 11e) and typical of Chromodoris elisabethina . The yellow margin differs in colour from that of the more orange rhinophores and gills, another characteristic of Chromodoris elisabethina and visible in the illustrations. Chromodoris elisabethina is more likely to have more black lines than quadricolor: Chromodoris quadricolor normally only has three black lines on the dorsum, and the Red Sea specimens with more black lines have been identified as Chromodoris strigata Rudman ( Yonow 2008). Chromodoris quadricolor is restricted to the Red Sea, where it is very common, apart from isolated specimen records from Socotra, Tanzania, and Chagos.