Neopomacentrus, Allen, 1975

Tang, Kevin L., Stiassny, Melanie L. J., Mayden, Richard L. & DeSalle, Robert, 2021, Systematics of Damselfishes, Ichthyology & Herpetology 109 (1), pp. 258-318 : 295-296

Neopomacentrus .

— There are currently 16 described species of Neopomacentrus , but Allen et al. (2017d) suspected that several species remain undescribed which they estimated would raise the species count to at least 18, including one identified therein as N. aff. bankieri . These fishes are often called demoiselles, a common name shared with species in other genera, mainly Chrysiptera spp. (Allen, 1991) . All species of Neopomacentrus share an elongate, gracile body shape (body depth 2.2–2.8 in SL) with a forked or lunate caudal fin, filamentous caudal-fin lobes, soft dorsal and anal fins with filamentous extensions posteriorly, and incisiform teeth with notched or flattened tips (Allen, 1975a, 1991; Jenkins and Allen, 2002; Randall and Allen, 2005; Allen et al., 2017d). Their appearance is superficially similar to zooplanktivorous species in other genera, which tend to be small and fusiform with a highly protrusible mouth and forked caudal fin for continuous swimming in the water column (Davis and Birdsong, 1973; Emery, 1983). Species of Neopomacentrus often assemble in midwater feeding aggregations (Allen, 1975a). Two species, N. aquadulcis and N. taeniurus , are among the few pomacentrids known to enter or reside in freshwater and brackish habitats (Allen, 1975a, 1989; Jenkins and Allen, 2002). The genus is native to the Indo-West Pacific, but one species, N. cyanomos , has recently become established in the Atlantic (Gulf of Mexico) by hitchhiking on offshore petroleum platforms transported across ocean basins ( González-Gándara and de la Cruz-Francisco, 2014; Robertson et al., 2016a, 2016b, 2018). A similar dispersal mechanism has been suggested as a possibility for the westward colonization of Brazilian waters by Chromis limbata (Anderson et al., 2017, 2020).

Because the condition of the preopercular margin (smooth vs. serrated) was the main character serving to distinguish between membership in the then-sprawling Abudefduf versus the equally sprawling Pomacentrus of the time, variation in that character among different species of Neopomacentrus led to their uncertain classification prior to the establishment of the genus (Allen, 1975a; Dor and Allen, 1977; Allen et al., 2017d). Since its description by Allen (1975a), the composition of the genus has remained stable even though species identifications have been challenging in some cases (Allen and Randall, 1981; Robertson et al., 2018), including for the presumed type species, N. anabatoides (Randall et al., 2005) . Allen and Randall (1981) divided the genus into two groups based on the conditon of the suborbital (i.e., infraorbital) margin: exposed vs. hidden by scales. They recognized the species with an exposed suborbital margin as the ‘‘ ‘ bankieri ’ complex’’ ( anabatoides , bankieri , fallax [¼ taeniurus ], filamentosus , fuliginosus , taeniurus , violascens , and xanthurus ). Subsequently, Allen et al. (2017d) considered N. aktites a part of this complex because of its exposed suborbital margin. Neopomacentrus aquadulcis was not designated as a member of the bankieri complex, but it was described as having a naked suborbital ( Jenkins and Allen, 2002: 381). Within the bankieri complex, four species ( N. aktites , N. anabatoides , N. filamentosus , and N. taeniurus ) were further differentiated by dark outer margins (or markings) on both lobes of the caudal fin (Allen and Randall, 1981; Allen et al., 2017d). Our dataset included all currently described species except N. anabatoides .

Monophyly of Neopomacentrus was strongly supported (98% bootstrap), a result which concurs with most past studies ( Quenouille et al., 2004; Hofmann et al., 2012; Litsios et al., 2012a, 2012b; Frédérich et al., 2013; DiBattista et al., 2016; Mirande, 2016; Gaboriau et al., 2018; Delrieu-Trottin et al., 2019). We found support (100% bootstrap) for the previously hypothesized sister relationship of N. aktites – N. filamentosus (Allen et al., 2017d) . However, the bankieri complex was not monophyletic. Instead, those species formed two separate clades: one with N. aktites , N. aquadulcis , N. bankieri , N. filamentosus , N. taeniurus , and N. violascens ; the other with N. fuliginosus and N. xanthurus . The latter clade was more closely related to the remaining Neopomancentrus, though the branches in this part of the tree are weakly supported (,50% bootstrap). We examined three of the four putative species comprising the dark-tailed group ( N. aktites , N. filamentosus , and N. taeniurus ), and they were resolved together (99% bootstrap), which supports the existence of a subgroup within the bankieri complex distinguished by dark edges or tips on the caudal fin. However, DiBattista et al. (2016) resolved N. anabatoides , the fourth species, as the sister taxon of N. bankieri . Sequences for that species appear to be unavailable.