Chelidonura normani, Ornelas-Gatdula & Dupont & Valdés, 2011

Ornelas-Gatdula, Elysse, Dupont, Anne & Valdés, Ángel, 2011, The tail tells the tale: taxonomy and biogeography of some Atlantic Chelidonura (Gastropoda: Cephalaspidea: Aglajidae) inferred from nuclear and mitochondrial gene data, Zoological Journal of the Linnean Society 163 (4), pp. 1077-1095 : 1090-1091

CHELIDONURA NORMANI SP. NOV.

( FIGS 1C, 1H, 1S , 3N–O , 4H–J , 6 )

Material examined: Holotype: Sand Dollar Beach , Stocking Island, Exumas, Bahamas (23°30′86″N, 75°44′56″W), 1–2 m depth, Dec 26, 2003, 8 mm long, leg. Anne DuPont ( LACM 3125 ).

Paratypes: Sand Dollar Beach , Stocking Island , Exumas, Bahamas (23°30′86″N, 75°44′56″W), 1–2 m depth, 7.i.2004, two specimens 7 mm long, leg. Anne DuPont ( LACM 3126 ). Sand Dollar Beach, Stocking Island, Exumas, Bahamas (23°30′86″N, 75°44′56″W), 1–2 m depth, 25.i.2006, two specimens 6 and 7 mm long, leg. Anne DuPont ( LACM 3127 ) . Monument Beach , Stocking Island, Exumas, Bahamas (23°31′49″N, 75°46′01″W), 1–2 m depth, 9.iii.2005, one specimen 4 mm long, leg. Anne DuPont ( LACM 3128 ) .

External morphology: Body narrow, elongate ( Fig. 6 ). Cephalic shield occupying the anterior half of the body length; visceral hump occupying the posterior half. Posterior end of the cephalic shield narrower and thicker, covering the anterior end of the visceral hump. Foot wide, forming two small lateral expansions that protrude on either side of the anterior end of the cephalic shield. Towards the middle of the body, the foot forms two short parapodia that can partially cover portions of the cephalic shield and the visceral hump. At the end of the visceral hump, the foot becomes covered by the two posterior expansions of the body, or ‘tails’. Posterior end of the visceral hump forming an arch that expands into two posterior expansions or ‘tails’. Left ‘tail’ long, triangular, occupying at least three-quarters of the width of the posterior end of the visceral hump. The right ‘tail’ is often a minute expansion, narrower than the left ‘tail’, almost invisible in some specimens. The shape and length of the ‘tails’ varies with the state of contraction of the animal.

Background colour variable, from pale brown to dark brown or black. Anterior end of the cephalic shield translucent grey, with the eye spots visible as two dark dots. Some specimens with thick yellow lines on the margins of the parapodia, the posterior arch of the visceral hump, the posterior end of the cephalic shield and near the anterior end of the cephalic shield. These lines can be completely absent in some specimens. Some specimens with bright yellow spots on the external surface of the parapodia near or in contact with the marginal yellow line. Some specimens with irregular opaque white or yellow dots and patches irregularly distributed over the dorsal surface of the cephalic shield and visceral hump as well as on the external surface of the parapodia and posterior ‘tails’. White or yellow dots and patches often more concentrated on the posterior end of the cephalic shield.

Anatomy: Penis shorter than the prostate, with a simple, non-bilobed apex ( Fig. 3N–O ). Shell internal, covering the posterior end of the viscera, calcified but extremely fragile and brittle. Shell apex with the protoconch attached. Protoconch about 290 Mm in maximum diameter, with a total of one and a quarter whorls ( Fig. 4H–J ). Nucleus with an irregular pattern of holes and ridges; the rest of the protoconch with a consistent growth pattern of irregular lines, all about the same width and depth.

Etymology: This species is dedicated to Norman DuPont, husband of Anne DuPont, for his help and support during the fieldwork in the Bahamas that produced the type material of this species.

Biology: This species is found only in the Bahamas. Specimens are found crawling on sandy bottoms during the day.

Remarks: Chelidonura normani can be characterized based on both morphological and molecular apomorphies. As discussed above, for all three genes, H 3, 16S, and COI, the Bahamas animals form a distinctive group with several unique substitutions. In all cases, specimens carrying those substitutions also have unique morphological traits, including the shape of the penis, the size and shape of the protoconch, and the morphology of the posterior ‘tails’ (all discussed in the Results section above). However, the external coloration of C. normani is highly variable and this variability is well within the range of C. berolina and these two species cannot be distinguished on the basis of their colour.

Figures

Figure 1. External morphology of some specimens of Chelidonura showing the range of colour variation. Specimens are grouped according to the authors’ interpretation of species boundary hypotheses proposed in the literature. A–G, specimens similar to the original description of Chelidonura berolina Er. Marcus & Ev. Marcus, 1970: A, original drawing of C. berolina (from Marcus & Marcus, 1970); B, specimen from Bahamas (LACM 176429); C, specimen from Bahamas (LACM 3127); D, specimens from Bahamas (LACM 176427); E, specimen from Bahamas (LACM 3127); F, specimen from Yucatan, Mexico; G. specimen from Bahamas (LACM 176425). H–M, specimens similar to the original description of Aglaja hummelincki Er. Marcus & Ev. Marcus, 1970: H, specimen from Bahamas (LACM 3127); I, specimen from Bahamas (LACM 176427); J, specimen from Bahamas (LACM 176425); K, specimen from Bahamas (LACM 176426); L, specimen from Bahamas (LACM 176425); M, original drawing of A. hummelincki (from Marcus & Marcus, 1970). N–P, specimens similar to the original description of Chelidonura juancarlosi Ortea & Espinosa 1998: N, original drawing of C. juancarlosi (from Ortea & Espinosa, 1998); O, specimen from Bermuda (LACM 176434); P, specimen from Bahamas (LACM 173215). Q–S, specimens similar to the original description of Chelidonura mariagordae Ortea et al. 2004: Q, specimen from Bahamas (LACM 176435); R, original photograph of C. mariagordae (from Ortea et al., 2004); S, specimen from Bahamas (LACM 3128).

Figure 3. Drawings of the penis and prostate of several specimens examined. A–K, Chelidonura berolina: A, specimen from Bahamas (LACM 176428); B, specimen from Bahamas (LACM 176428); C, specimen from Bahamas (LACM 176431); D, specimen from Bahamas (LACM 176428); E, specimen from Bahamas (LACM 176432); F, specimen from Bahamas (LACM 176428); G, specimen from Bahamas (LACM 176435); H, specimen from Bahamas (LACM 176428); I, specimen from Bahamas (LACM 176428); J, specimen from Martinique (LACM 176437); K, specimen from Roatán, Honduras (LACM 176433). L–M, Chelidonura africana: L, specimen from Portugal (MNCN 15.05/46493); M, specimen from Portugal (MNCN 15.05/44368). N–O, Chelidonura normani sp. nov.: N, specimen from Bahamas (LACM 3126); O, specimen from Bahamas (LACM 3125). Abbreviations: pe, penis; pr, prostate.

Figure 4. Scanning electron micrographs of the protoconch morphology or apical shell morphology of some specimens examined. Arrows indicate transitions in growth line pattern. A–D, Chelidonura africana: A, specimen from Portugal (MNCN 15.05/46493); B, specimen from Portugal (MNCN 15.05/46488); C, specimen from Portugal (MNCN 15.05/44368); D, juvenile specimen from Azores, Portugal (MNCN 15.05/44367). E–G, Chelidonura berolina: E, specimen from Bahamas (LACM 172272); F, specimen from Bahamas (LACM 176427); G, specimen from Bahamas (LACM 176426). H–J, Chelidonura normani sp. nov.: H, specimen from Bahamas (LACM 3126); I-J, specimen from Bahamas (LACM 3127).

Figure 6. Type specimens of Chelidonura normani sp. nov. A, holotype (LACM 3125). B, paratype (LACM 3127). C, paratypes (LACM 3126). D, paratype (LACM 3128).