Connectivity across the Caribbean Sea: DNA barcoding and morphology unite an enigmatic fish larva from the Florida straits with a new species of sea bass from deep reefs off Curaçao

Abstract

Integrative taxonomy, in which multiple disciplines are combined to address questions related to biological species diversity, is a valuable tool for identifying pelagic marine fish larvae and recognizing the existence of new fish species. Here we combine data from DNA barcoding, comparative morphology, and analysis of color patterns to identify an unusual fish larva from the Florida Straits and demonstrate that it is the pelagic larval phase of a previously undescribed species of Liopropoma sea bass from deep reefs off Curaçao, southern Caribbean. The larva is unique among larvae of the teleost family Serranidae, Tribe Liopropomini, in having seven elongate dorsal-fin spines. Adults of the new species are similar to the golden bass, Liopropoma aberrans, with which they have been confused, but they are distinct genetically and morphologically. The new species differs from all other western Atlantic liopropomins in having IX, 11 dorsal-fin rays and in having a unique color pattern-most notably the predominance of yellow pigment on the dorsal portion of the trunk, a pale to white body ventrally, and yellow spots scattered across both the dorsal and ventral portions of the trunk. Exploration of deep reefs to 300 m using a manned submersible off Curaçao is resulting in the discovery of numerous new fish species, improving our genetic databases, and greatly enhancing our understanding of deep-reef fish diversity in the southern Caribbean. Oh the mother and child reunion is only a moment away. Paul Simon.

Figure 1. Larvae of western Atlantic Liopropomini.

A, Liopropoma olneyi sp. nov, USNM 426868, paratype, DNA #FLST 5001, 14.0 mm SL, Florida Straits, photo by Cedric Guigand. B, L. rubre, reared aquarium larva, photo by Christopher Paparo. C, L. carmabi, reared aquarium larva, photo by Christopher Paparo; D. Bathyanthias sp., Florida Straits, photo by Cedric Guigand.

Figure 2. Photomicrographs of cleared-and-stained larval Liopropoma olneyi, sp. nov. (USNM 426868, paratype, 14.0 mm SL) showing morphological evidence of its placement in the epinepheline serranid tribe Liopropomini.

A, whole specimen showing elongate, filamentous dorsal-fin spines, and inset showing close-up of thin, curved, first dorsal-fin pterygiophore. B, close-up of the spinous dorsal fin and fin supports showing separation of the distal radials of the third through last spinous dorsal-fin pterygiophores from the serially associated proximal-middle radials (right black arrow), and presence of a pterygiophore in the 7^th interneural space (left black arrow). C, close-up of bones of the opercular series showing absence of an elongate spine at the angle of the preopercle (lower black arrow) and presence of tiny spines on the lateral preopercular margin (upper black arrow). Photos by G. David Johnson.

Figure 3. Neighbor-joining tree derived from COI sequences for western Atlantic Liopropoma and related taxa.

The tree was rooted on Scorpaena plumieri, DNA #CUR11401. Divergence represented by scale bar = 7%. Photograph of Liopropoma rubre by Carole Baldwin and Lee Weigt; illustration of L. eukrines by Raymond Simpson; photograph of larva of Liopropoma olneyi, sp. nov., by Cedric Guigand; all other photographs by Ross Robertson and Carole Baldwin.

Figure 4. Liopropoma olneyi, sp. nov., USNM 426805, holotype, DNA #CUR 13200, 84.3 mm SL.

Photo by Ross Robertson and Carole Baldwin.

Figure 5. Liopropoma olneyi, sp. nov., VIMS 13590, paratype, 14.7 mm SL.

Photo by G. David Johnson.

Figure 6. Close-up images of swellings and pigmentation on elongate dorsal-fin spines in cleared larval Liopropoma olneyi, sp. nov., USNM 426868, paratype, 14.0 mm SL.

A, portions of several of the third through eighth dorsal-fin spines. B, distal end of second dorsal-fin spine. Photos by G. David Johnson.

Figure 7. Liopropoma olneyi, sp. nov.

A, in-situ photograph taken from the Curasub submersible at 125 m on the reef slope adjacent to the Curacao Sea Aquarium on 7 Aug 2013. Photo courtesy of Substation Curacao. B, aquarium photograph by Barry Brown.

Figure 8. Comparison of Liopropoma olneyi, sp. nov., and L. aberrans.

A, L. olneyi, Curacao (USNM 426808, paratype, DNA #CUR12225, 73 mm SL). B, L. aberrans, Cuba (illustration from original description [21: Plate 12–2], 115 mm SL). C, L. aberrans, Bahamas (photograph from redescription of L. aberrans [6: Fig. 1], UMML 22324, 112 mm SL). D, L. aberrans, Curacao (USNM 426807, DNA #CUR 12226, 102 mm SL). Photos A and D by Ross Robertson and Carole Baldwin.

Figure 9. The strict consensus tree of a maximum parsimony analysis of the COI region among western Atlantic Liopropoma and related taxa.

Numbers above branches represent bootstrap support values.