Coralliophila curacaoensis sp. nov. Potkamp and Hoeksema
Etymology. Named after the island of Curaçao, the type locality of C. curacaoensis sp. nov.
Type material. Holotype RMNH.5004326 (Figs. 20a-f) and nine paratypes RMNH.5004323-5004325 (only molecular sequences deposited), RMNH.5004327-5004328, RMNH.5004329-5004332 (only soft tissue deposited) (Figs. 20g-y).
Type locality. Leeward coast of Curaçao, Playa Daaibooi, 12°13’N, 69°05’W, 11 m depth (holotype RMNH.5004326 and paratypes RMNH.5004323 and RMNH.5004327-5004332). Playa Kalki, 12°22’N, 69°09’W, 8 m depth (paratype RMNH.5004324) and 10 m depth (paratype RMNH.5004325).
Distribution. Only recorded from the type locality, Curaçao, southern Caribbean. Specimens were found in association with corals of the scleractinian species Madracis auretenra Locke, Weil and Coates, 2007.
Diagnosis. Small size, shell angular, rhomboidal in shape. Aperture oval, elongated. Cone-shaped spire with incised sutures. Teleoconch sculptured with spiral cords, on the body whorl relatively high and widely set. Two high imbricated spiral cords around the shoulder, spiral cords decreasing in size towards the anterior end. Eight to nine varices per whorl, giving the shell a latticed appearance. Umbilical area moderately wide, with imbricate fasciole and narrowly open umbilical furrow. Operculum transparent to pale red.
Description. Small shell size compared to its congeners: largest specimen with a length of 8.9 mm, width 5.8 mm. Shell rhomboidal in shape with teleoconch consisting of 3+ whorls. Protoconch eroded on holotype. Spire cone-shaped, sides angular to almost flat, sutures moderately incised. Body whorl more than half of the total shell length, basal outline sharply curving at the shoulder, anterior to the shoulder straight, in some specimens more inflated. Aperture long, oval. Outer lip fimbriated; inner lip gently arcuate. Siphon canal broadly open, relatively long at around one fifth of the total shell length; umbilical area moderately wide, fasciole imbricate, umbilical furrow narrowly open.
Teleoconch sculptured with widely set spiral cords. Two high spiral cords on the body whorl, the first one located at the shoulder, the second directly anterior, widely spaced. Several, also widely spaced, smaller cords anterior to the two large cords (three on the holotype), decreasing in size. Spiral cords with relatively large imbricated scales, clearest at the intersection between varices and spiral cords. On the holotype, five small cords posterior to the shoulder on the body whorl, more closely set compared to cords anterior to the shoulder. Eight to nine varices per whorl, three of which very large on the body whorl of the holotype.
Shell colour ivory white. Operculum transparent to pale red.
Remarks. Among its Caribbean congeners, C. curacaoensis sp. nov. is the smallest species. It has only been found in association with M. auretenra. The mitochondrial marker 12S rRNA of C. curacaoensis differs at on average 17.1% of positions from C. caribaea and 18.6% of positions from C. galea. For the COI marker, 24.6% of positions are on average different in C. caribaea compared to C. curacaoensis, and 21.9% of positions compared to C. galea.
Coralliophila curacaoensis sp. nov. resembles most C. caribaea, but it differs from that species in that the spiral cords on the body whorl are smaller on C. curacaoensis and more numerous and closely set on C. caribaea. Consequently, C. caribaea lacks the strongly fimbriated outer lip of C. curacaoensis. The colour of the operculum of C. caribaea is a deeper red than the operculum of C. curacaoensis. Sutures are generally less incised in C. caribaea.
Coralliophila galea, differs mainly from C. curacaoensis sp. nov. in having a more globose shell, having more numerous, closely set, spiral cords, lacking the high spiral cords and a fimbriated outer lip. The spire of C. galea is shorter and sutures are not incised as in C. curacaoensis.
Several other species of the genus Coralliophila are known from the western Atlantic, two of which resemble C. curacaoensis sp. nov.: C. pacei Petuch, 1987 and C. richardi (Fischer, 1882). Coralliophila pacei has only been found in shallow water along the southeastern coast of Florida (Petuch and Myers, 2014). It shows two large spiral cords on the body whorl, with two small cords in between, which are absent in C. curacaoensis. The large cords on C. curacaoensis are more widely spaced, decreasing in size anterior to the large cords. Furthermore, varices on C. curacaoensis are not as low as on C. pacei.
Coralliophila richardi is a deep-water species found on cold-water reefs formed by the scleractinians Lophelia pertusa (Linnaeus, 1758) and Madrepora oculata Linnaeus, 1758, across the North Atlantic (Bouchet and Warén 1985; Oliverio and Gofas, 2006; Schembri et al., 2007; Taviani et al., 2008, 2009). Coralliophila richardi lacks the high, imbricate spiral cords and therefore the fimbriated outer lip, which are shown by C. curacaoensis.
Coralliophila fontanangioyae Smriglio and Mariottini, 2000 is known from the Canary Islands in the Eastern Atlantic. It is relatively closely related but genetically distinct from C. curacaoensis sp. nov. (Fig. 15). Oliverio et al. (2009) published a 12S rRNA sequence from C. fontanangioyae, which differs on average at 21.1% of positions from the newly sequenced 12S rRNA sequences of C. curacaoensis. Morphologically, C. fontanangioyae resembles C. curacaoensis in shell ornamentation but its whorls have less sharper edges than those of C. curacaoenis (Gofas, 2005). Coralliophila fontanangioyae occurs in association with the deep-water scleractinian Madracis asperula Milne Edwards and Haime, 1849(Smriglio and Mariottini, 2000; Oliverio et al., 2009), whereas C. curacaoenis and C. galea, have been found in association with colonies of Madracis auretenra.
Coralliophila meyendorffii (Calcara, 1845), the sister species of C. fontanangioyae (Fig. 15), has a much finer ornamentation and its spirals have edges that are less sharp than those of C. curacaoenis sp. nov. (see Oliverio and Gofas, 2006). It has an East Atlantic - Mediterranean distribution over a wide depth range that includes the Adriatic Sea (Oliverio and Mariottini, 2001; Oliverio and Gofas, 2006; Kružić et al., 2013). It predates on the scleractinians Balanophyllia europaea (Risso, 1826) or Cladocora caespitosa (Linnaeus, 1767) (Oliverio and Mariottini, 2001b; Kružić et al., 2013), while it is also known as an associate of sea anemones (Oliverio and Mariottini, 2001b; Oliverio and Gofas, 2006).
Other East Atlantic Coralliophila species are predominantly known from deep water and have not been recorded from the West Atlantic and not as associates of either scleractinians or alcyonaceans (Pons-Moyà et al. 2001; Oliverio and Gofas, 2006; Oliverio et al., 2009).