Cyerce pavonina Bergh, 1888

Moreno, Karina, Medrano, Sabrina, Gosliner, Terrence M., Wilson, Nerida G., Krug, Patrick J. & Valdés, Ángel, 2025, Phylogenetic systematics of the genus Cyerce Bergh, 1870 (Mollusca: Heterobranchia: Sacoglossa: Caliphyllidae) from the Pacific and Indian oceans with descriptions of nine new species, Zoological Journal of the Linnean Society 204 (1) : -

Cyerce pavonina Bergh, 1888

( Figs 20A, 21, 22A)

Cyerce pavonina Bergh 1888: 764–769 , pl. 77, figs 3–5, pl. 78, figs 10–18, pl. 79, figs 22–25. Type locality: Mauritius.

Type material

Cyerce pavonina — no type material known to exist, not found at NHMD.

Material examined

‘ The Deep Blue’ , 13.91763ºN 120.6039ºE, Verde Island Passage , Calatagan , Luzon Island , Philippines, 18 May 2014, leg. VIP Team , 1 specimen 11 mm preserved length, dissected (isolate MM42 , CASIZ 202132 ). Diamond Head , Oahu, Hawaiian Islands, USA, 1 Oct 2000, 1 m depth, leg. C. Pittman, 1 specimen ( CASIZ 163778 ) .

Range

Western and Central Pacific, and Indian Ocean (Rudman 2008, Gosliner et al. 2018).

Description

External morphology: Body colour light brown ( Fig. 20A). Pericardium elevated, circularly shaped, lighter than rest of body. Rhinophores light brown, covered with white flecks scattered throughout. Cerata inflated, obovate; outer side dark brown with translucent tubercles and white flecks; inner side lighter brown with cream patch, two dark dorso-medial brown spots, one brown spot located below ceratal margin, another spot located beneath first. Cerata margin outlined with dark yellowish to orange band, with white tubercles appearing to give cerata dentate-like structure. Dorsal side of the foot light brown, foot sole greenish grey.

Internal morphology: Pharynx about 3 mm in length; pharyngeal pouch much larger than buccal bulb. Radula with 10 teeth in an 11-mm preserved length specimen ( CASIZ 202132); 6 on descending limb, 4 on ascending limb ( Fig. 21A). Teeth elongate, with wide bases. Leading tooth about 500 µm in length, with two rows of ~24 triangular denticles along either side ( Fig. 21B). Size of denticles varies along tooth, smaller near base and tip. Ascus not observed. Penis with penial stylet at opening ( Fig. 22A). Penial stylet cylindrical, hollow with oval opening, about 200 µm in length.

Ecology

Associated with the green algae Halimeda spp.

Remarks

Bergh’s (1888) original description of Cyerce pavonina Bergh, 1888 was based on a single preserved specimen from Mauritius and field notes provided by [Karl August] Moebius [Möbius]. The main diagnostic characteristics of this species as described by Bergh (1888) included a yellow-brown head colour, dorsal yellow-brown cerata covered with whitish warts, and a grey foot sole. Bergh (1888) further described the cerata of C. pavonina as being leaf-shaped with both sides covered by tubercles and a brown tip and white base. Bergh (1888) also described the outer side of the cerata as having a brown colour darker than the inner side, which was described as white or lighter in colour. The colour illustration of C. pavonina by Möbius, reproduced by Bergh (1888: pl. 77, fig. 3) and herein ( Fig. 5F) also shows two dorso-medial brown spots, a trait that along with the brown cerata covered with whitish tubercles closely resembles the characteristics of our specimens. The radular morphology of C. pavonina was also described and illustrated by Bergh (1888: pl. 78, figs 16, 17), which closely resembles that of our specimens; both have very narrow and elongate teeth with numerous denticles and wide bases. All these morphological traits described by Bergh (1888) closely resembles the specimens studied herein and therefore we confidently assign our specimens to C. pavonina .

Kay (1979) described a specimen from the Hawaiian Islands as C. nigricans that closely resembles C. pavonina . The description of the cerata colour by Kay (1979) is very similar to our specimen of C. pavonina , as being translucent brown with an orange yellow band along the margin. Kay (1979) also mentioned the cerata as dark brown with white spots on one side of the cerata and white pustules with blue spots on the other, a trait that we did not observe in our specimens. The identity of Kay’s (1979) specimens remains unclear as additional species with similar external morphology are present in the Hawaiian Islands; see description of C. liliuokalaniae sp. nov.

Rudman’s (2008) morphological description of a specimen of Cyerce pavonina from Tanzania closely resembles the specimen studied herein. However, Rudman’s (2008) specimen appeared to have a light brown band across the head of the animal, a trait we could not verify in our specimens. Whether the specimen described by Rudman (2008) and our specimens belongs to the same species would require further investigation. Moreover, examination of online images of C. pavonina from the Philippines indicated that they have a light brown band across the head. Therefore, multiple pseudocryptic species may be currently identified as C. pavonina .

Cyerce pavonina was recovered in the phylogenetic analyses as sister to C. goodheartae sp. nov. ( Fig. 1B), but differed in colour and radular morphology. Compared to C. pavonina , the cerata of C. goodheartae sp. nov. were more translucent, light brown, and lacked tubercles throughout. The radular teeth of C. goodheartae sp. nov. are shorter and wider than those of C. pavonina . The radular and penial morphology of C. pavonina are also similar to those of C. liliuokalaniae sp. nov. in several respects. For example, both species have very elongate, slender radular teeth with triangular denticles, and short, cylindrical penial stylets.

Bergh (1888) mentioned the penial stylet of Cyerce pavonina appeared to be similar morphologically to that of C. nigricans , but shorter in length. The penial stylet of C. nigra is cylindrical with an oval opening, but it has a sharp, pointed tip, clearly differing from Cyerce pavonina .