Two cryptic and sympatric species of Philinopsis (Cephalaspidea: Aglajidae) in the Bahamas distinguished using molecular and anatomical data

Abstract

Sequence data of nuclear and mitochondrial genes obtained from specimens of Philinopsis collected in the Bahamas revealed two genetically distinct groups. Further examination of the shell and male reproductive morphology revealed consistent anatomical differences between them, corroborating that they are distinct species. The two species also display consistent differences in external morphology and colour pattern that became evident only after the molecular information was analysed. A review of the literature suggests that one of the species is Philinopsis petra, a widespread species in the Caribbean and northern Brazil, whereas the other is described here as a new species. Although both are sympatric in the Bahamas, they appear to be ecologically analogous, suggesting that they might have speciated allopatrically. Thirteen specimens initially identified as Philinopsis petra and two specimens of P. pusa (Ev. Marcus & Er. Marcus, 1976) were used in this study (Table 1). Most specimens were collected at Stocking Island, Exumas, Bahamas (Fig. 1). Specimens were photographed alive, narcotized using a 1 M solution of MgCl 2 , and preserved in 70% ethanol. Two additional specimens were collected in Tobago and Martinique and preserved in 10% formalin. All the specimens examined are deposited at the Natural History Museum of Los Angeles County, USA (abbreviated LACM).

New data on the heterobranch gastropods (‘opisthobranchs’) for the Bahamas (tropical western Atlantic Ocean)

“…Taylor & Hellberg (2003, 2005 as a result of studies on reef fish provided the first molecular based support for this biogeographical break. Recent molecular systematics research on heterobranch sea slugs conducted by Ornelas-Gatdula et al (2011), Ornelas-Gatdula & Valdés (2012 and Carmona (2013) confirmed the presence of new cryptic species in the Bahamas not known elsewhere in the Caribbean province.…”

“…When it comes to heterobranch sea slugs (the traditional opisthobranchs sensu Burn & Thompson, 1998), Valdés et al (2006) reported the occurrence of 308 species in the region and since then several others have been cited (e.g. Pola et al, 2008;Caballer & Ortea, 2011;Ornelas-Gatdula et al, 2011;Ornelas-Gatdula & Valdés, 2012;Ortigosa & Valdés, 2012). Likely the most comprehensive treatises about the Bahamian molluscs with focus on the northern island of Abaco are those of Redfern (2001Redfern ( , 2013 where 188 species of heterobranch sea slugs are cited (sensu traditional opisthobranchs; Redfern, 2013).…”

“…Ornelas-Gatdula et al, 2011;Ornelas-Gatdula & Valdés, 2012;Carmona, 2013;Petuch, 2013). Petuch (2013) in his recent work on the biogeography and biodiversity of western Atlantic molluscs refers to a Bahamian sub-province and mentions the existence in these islands of several centres of speciation resulting from isolation caused by extensive open areas of 'sterile' oolitic sands acting as ecological barriers promoting allopatry and the development of unique sets of species.…”

The bubble snails (Gastropoda, Heterobranchia) of Mozambique: an overlooked biodiversity hotspot

“…Several recent works using molecular phylogenetics have showed that species of sea slugs regarded as highly variable in colour were in fact complexes of several species (e.g. Ornelas-Gatdula and Valdés 2012 [Philinopsis]; Carmona et al 2014b [Spurilla]), but there are also opposite examples; for instance, Malaquias et al (2016) have confirmed that distinct colour morphs of Chelidonura fulvipunctata are conspecific.…”

First record of the Bahamian mollusc Spurilla dupontae (Mollusca: Aeolidiidae) in the Caribbean subprovince

“…The micro-speciation phenomenon is particularly evident in groups with non-planktotrophic development (Ornelas-Gatdula et al 2011;OrnelasGatdula and Valdés 2012), especially when studied as a whole in the area . The high rate of endemism observed may be the result of the isolation, caused by extensive open areas of "sterile" sands, which act as ecological barriers (Petuch 2013), or it may be explained by post-recruitment ecological factors, or historic vicariance (Ornelas-Gatdula and Valdés 2012;Carmona et al 2014).…”