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| Trachinotus macrospilus
Smith-Vaniz & Walsh, 2019
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Abstract
Diagnoses, comparisons, photographs and distribution maps are given for three previously described Indo-West Pacific species of Trachinotus that develop spots on their sides as adults. A new species, Trachinotus macrospilus, is described from the Marquesas Islands where it is endemic and the only species of the genus present. It differs from the other spotted Indo-West Pacific species most noticeably in having adults with only one or two large spots on each side, the largest spot larger than the iris diameter, and in having no large spot positioned above the pectoral fin. An identification key is given for all Indo-West Pacific species of Trachinotus and a molecular phylogeny, including 16 of the 20 valid species of Trachinotus is presented. A neotype is designated for Scomber botla Shaw, 1803.
Key words: taxonomy, Carangidae, Trachinotus macrospilus n. sp., endemic, Marquesas Islands
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| FIGURE 4. Trachinotus macrospilus, all from the Marquesas Islands: A, USNM 409238, 292 mm FL, holotype (left side); B, USNM 409238, holotype (right side reversed); C, USNM 409385, 142 mm FL.
Photographs by Jeffrey T. Williams.
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| FIGURE 3. Trachinotus macrospilus, MCZ 29732, 211 mm FL, Marquesas Islands. After Kendall and Goldsborough, 1911, plate 1, as “Trachinotus oblongus.” |
Trachinotus macrospilus new species
Marquesas dart
Diagnosis. A species of Trachinotus in which adults have only 1 or 2 large black spots on their sides; the largest spot larger than iris diameter (usually smaller than iris diameter in T. baillonii and equal to or larger than eye diameter in T. botla and T. coppingeri), and in having no large spot positioned above the pectoral fin (adults of T. botla and T. coppingeri have 1 or 2 large spots above the pectoral fin). Height of largest spot plotted against head length is also larger than in T. baillonii (Fig. 6). Heights of dorsal- and anal-fin lobes of adults are also usually shorter than in the other three species (Fig. 7). Dorsal fin VI-I, 23‒26; anal-fin II-I, 23‒25; vomerine tooth patch usually chevron shaped and palatine tooth patch relatively long (Fig. 2B).
Distribution. (Fig. 11) Endemic to the Marquesas Islands.
Remarks. With a reported shore fish fauna of 495 species and 13.7% endemism (Delrien-Trottin et al., 2015), the Marquesas Islands have the third greatest species-level endemism for insular coral reef fishes in the Indo-Pacific. Easter Island, with a much smaller total fauna of only 169 marine fish species and a similar geographic size, has a 21.7% rate of endemism (Randall and Cea, 2011), exceeded only by Hawaii with about 25% endemism of its marine ichthyofauna (Randall, 2007). The Marquesas Islands are high islands of recent volcanic origin and, as discussed by Randall and Earle (2000), combined with their isolation both geographically and hydrographically (westernly South Equatorial Current and major upwelling events) has led to the high level of endemism of the ichthyofauna.
Etymology. From the Greek makros (long, large) and spilos (spot), in reference to the relative height of the largest and usually single spot on the mid-side of the body of adults.
William F. Smith-Vaniz and Stephen J. Walsh. 2019. Indo-West Pacific Species of Trachinotus with Spots on Their Sides as Adults, with Description of A New Sspecies Endemic to the Marquesas Islands (Teleostei: Carangidae). Zootaxa. 4651(1); 1–37. DOI: 10.11646/zootaxa.4651.1.1
