Clarifying the Northern Extent of the Diamond Stingray (Dasyatis dipterura) in Southern California

Abstract

Accurate records of biogeographic distributions (latitude and elevation) are becoming increasingly important as species shift their distribution in response to global climate change (Walther et al. 2002). The Southern California Bight is a transition zone between the Oregonian and San Diegan biogeographic zones (Horn et al. 2006). Therefore, range extensions are commonly documented in the area (Pondella 1997; Lea and Rosenblatt 2000; Miller and Curtis 2008; Moore et al. 2011; among others). On 27 October 2011, a single Diamond Stingray (Dasyatis dipterura) was taken in Marina del Rey harbor (33u 58.9739N 118u 27.2459W) in Marina del Rey, California during an environmental survey using a 7.6-m otter trawl at a depth of 4.3 m. The individual weighed 1.65 kg and measured 247 mm disc width (Figure 1). Key characters used in the identification to differentiate it from other common species, such as Round Stingray (Urobatis halleri) and Bat Ray (Myliobatis californica), include the disc shape and the presence of a keel on the tail. The tail keel is unique to Diamond Stingray in comparison to both Round Stingray and Bat Ray. Being alive and in apparently good health, the animal was photographed and released. Diamond Stingray nomenclature has a multifaceted history. Originally described in a May 1880 publication by Jordan and Gilbert (1880) and again by Jordan and Gilbert (1882) as Dasybatis dipterurus, the current nomenclatural combination first appeared in Jordan and Evermann (1896). Garman (1880) described Tygon brevis in his October 1880 review of collections at the Harvard University Museum of Comparative Zoology. Garman (1913) synonymized all prior names, including T. brevis, under Dasybatus brevis, but lacked any reference to Jordan and Gilbert (1880). Instead, Garman (1913) included Jordan and Gilbert (1881), which introduced the name Dasybatus dipterurus. Nishida and Nakaya (1990) followed Garman (1913) and treated Dasyatis dipterurus (Jordan & Gilbert, 1880) with Dasybatus brevis. Eschmeyer (1998) noted dipterurus predated brevis (May and October 1880, respectively) and therefore synonymized brevis under dipterurus and recognized dipterura as the correct species name. Accordingly, Nelson et al. (2004) removed reference to brevis from North American waters in recognition of Eschmeyer’s clarification of the species’ nomenclature. We utilize the presently accepted Dasyatis dipterura (Page et al. 2013). The Diamond Stingray northern range limit is no less enigmatic than its nomenclature. Current literature (Love et al. 2005) lists the northern range endpoint as central California (Grove and Lavenberg 1997 as Dasyatis brevis), although the true northern extent is unsubstantiated by a voucher specimen collected north of 33.7uN latitude, or Long Beach, California [LACM 48829.001; Fishnet2 (www.fishnet2.net); SIO (http:// collections.ucsd.edu); MCZbase (http://mczbase.mcz.harvard.edu)]. Prior work recorded a range to southern California and ‘‘possibly British Columbia’’ (Hart 1973). The Hart reference was founded on records of a Dasyatis sp. being caught in Kyuquot on Bull. Southern California Acad. Sci. 113(3), 2014, pp. 232–235 E Southern California Academy of Sciences, 2014