Rhinopteridae, Jordan & Evermann, 1896

Elasmobranch, Its Implications For Global, Parasitology, Diversity And, Naylor, G. J. P., Sc, Caira, J. N., Ct, Jensen, K., Ks, Rosana, K. A. M., Fl, White, W. T., Csiro, Tas, Last, P. R., Csiro & Tas, 2012, A Dna Sequence-Based Approach To The Identification Of Shark And Ray Species And Its Implications For Global Elasmobranch Diversity And Parasitology, Bulletin of the American Museum of Natural History 2012 (367), pp. 1-262 : 79-81

Rhinopteridae (cownose rays)

Rhinoptera species

In total, 52 specimens of cownose rays were included in the analysis. The identities of most of these specimens were difficult to determine using either morphological or molecular criteria, because the taxonomy of this genus remains so relatively poorly known. Even key characters such as tooth shape and number appear to be intraspecifically variable. Hence, in assigning names to taxa we have taken a conservative approach. Morphology, molecular differences, and geographic location were used in combination to make these determinations. In general, only in instances in which at least two of these three criteria were congruent, were the specimens comprising a cluster assigned a unique name. In total we believe our specimens represent as many as eight species of Rhinoptera .

The phenotype and geography haplotype maps for the 52 specimens of Rhinoptera included here are illustrated in figure 99A and 99B, respectively. The phenotype map supports the validity of at least seven of these species in that their haplotypes are distinct and, in the cases of species represented by multiple specimens, the haplotypes of their members are tightly clustered. However, it also serves to highlight issues with R. steindachneri and R. bonasus , which are addressed in the sections treating these species below.

Rhinoptera steindachneri (Pacific cownose ray)

complex ( fig. 61)

The analysis yielded a cluster comprised of seven specimens of Rhinoptera steindachneri from the Gulf of California, seven specimens from the Gulf of Mexico, and one from North Carolina all originally identified as Rhinoptera bonasus . The range of pairwise differences among the 15 members of this cluster was 0–9 (with an average of 3.8). However, these specimens differ from one another morphologically in a number of respects. For example, the specimens from the Gulf of California appear to be fully consistent with the eastern Pacific species, Rhinoptera steindachneri , the type locality of which is in the Gulf of California. In contrast, the configuration of the tooth plates of the specimens from the Gulf of Mexico and North Carolina resemble those of Rhinoptera brasiliensis , even more than they do those of R. bonasus . Furthermore, these specimens clustered well outside specimens from the western Atlantic considered to be morphologically consistent with R. bonasus (see below). Unfortunately, no confirmed specimens of the southwestern Atlantic R. brasiliensis were included in the analysis. Until such time as the New World members of this genus can be examined in more detail, despite the mixed nature of this cluster, we have retained the designation Rhinoptera steindachneri for the specimens from the Gulf of California and have adopted Rhinoptera cf. steindachneri for the members of this cluster that occur in the other localities.

However, the haplotype map colored by phenotype ( fig. 99A) does not support this line of reasoning. Not only is one haplotype shared by specimens identified as R. steindachneri and R. cf. steindachneri , but the haplotypes of specimens of these two taxa are very similar and, in fact, comprise a single group. This suggests the alternative interpretation that R. steindachneri occurs not only in the eastern Pacific, but also in the Gulf of Mexico, and possibly also the western Atlantic Ocean, where it is sympatric with Rhinoptera bonasus .

Rhinoptera sp. 1 ( fig. 61)

Clustering along with but outside the specimens in the Rhinoptera steindachneri complex was a specimen collected from Senegal (GN5978). The average of the pairwise differences between this specimen and those in the former cluster of 15 specimens was 20.8. Given its degree of genetic divergence and disparate locality, this specimen has been given a separate designation until such time as additional specimens from the eastern Atlantic can be examined in more detail.

Rhinoptera jayakari ( Oman cownose ray) ( fig. 61)

The analysis also yielded a cluster comprised of 10 specimens collected from a diversity of localities including Borneo, Mozambique, and the Gulf of Oman. The range of pairwise differences among specimens in this cluster was 0–17, with an average of 8.3. While there was some evidence of two subclusters within this cluster, the specimens in these two subclusters overlapped in geography and had an average of the mean pairwise differences of 13.7. At this time, all specimens in this cluster have been referred to as Rhinoptera jayakari following Last et al. (2010c).

Rhinoptera bonasus (cownosed ray) complex

( fig. 61)

The analysis yielded a cluster comprised of 18 specimens from a diversity of localities in the western Atlantic including Virginia, North Carolina, and South Carolina. The range in pairwise differences among members of this cluster was 0–8, with an average of 1. The fact that these specimens grouped away from those comprising the R. cf. steindachneri cluster, which also included a specimen from the western Atlantic, as noted above, suggests that this region may be home to two sympatric species of Rhinoptera . These specimens have been given the designation R. bonasus , based on their morphology and because the type locality of this species is New York. The average of the pairwise differences between R. bonasus and its sympatric congener R. cf. steindachneri was 86.

Grouping along with but outside the members of the former cluster was a second specimen collected from Senegal. The average of the pairwise differences between this specimen and those of the R. bonasus cluster was 19.4. Thus, while this specimen from Senegal exhibited a tooth pattern similar to that of R. bonasus , given its geography and genetic difference, it has been referred to here as R. cf. bonasus . The difference between this specimen and that of the other from Senegal ( Rhinoptera sp. 1 ) was 80. This suggests that Senegal may also be home to two sympatric species of Rhinoptera .

The haplotype map ( fig. 99A) supports the contention that R. cf. bonasus from Senegal is distinct from R. bonasus . However, it also confirms that a second species ( Rhinoptera sp. 1 ) occurs sympatrically with R. cf. bonasus in Senegal.

Rhinoptera neglecta (Australian cownose ray)

( fig. 61)

The analysis also yielded a cluster comprised of five specimens of R. neglecta from northern Australia. One of these specimens came from the Australian National Fish Collection (GN4662 5 ANFC H 3915-01). The range of pairwise differences among these specimens was 0–3, with an average of 1.2.

Rhinoptera javanica (Javanese cownose ray)

( fig. 61)

Two specimens identified as R. javanica (see Last et al., 2010c), one from eastern Malaysian Borneo and one from Vietnam, grouped immediately outside the R. neglecta cluster. These specimens differed from one another by nine bases. The average of the pairwise differences between these specimens and those of R. neglecta was 22.6.