Tetracha (Tetracha) sobrina caicosensis, Ward 1 & Davidson & Brzoska, 2011

Ward 1, Robert D., Davidson, Robert L. & Brzoska, David, 2011, Tetracha Hope 1838 of the Turks and Caicos Islands (Coleoptera, Carabidae, Cicindelinae), ZooKeys 147, pp. 85-97 : 93-96

Tetracha (Tetracha) sobrina caicosensis subsp. n. Figs 9 -11

Type material.

(45 specimens) Holotype ♂: "TURKS & CAICOS/ ISLANDS, South Caicos-/ Victoria Salina, 1m/ 21°29.6'N, 71°31.5 W / D. Brzoska 5-7-I-2010" (CMNH). Allotype ♀: same data as holotype (SEMC). Paratypes (43) as follows: 30 same data as holotype (12 ♂♂, 7 ♀♀ DBC; 2 ♂♂, 2 ♀♀ CMNH; 1 ♂, 1 ♀ AMNH; 1 ♂, 1 ♀ FSCA; 1 ♂, 1 ♀ RNC; 1 ♂ SEMC); 13 labelled: "TURKS & CAICOS/ ISLANDS, Grand Turk-N./ end Saunders Pond, 1m/ 21°29.1'N, 71°08.9'W / D. Brzoska 11-13-I-2010" (11♂♂, 1♀ DBC; 1 ♂ CMNH).

Type locality.

South Caicos Island in the Turks & Caicos Islands group.

Distribution.

Known only from two islands in the Turks & Caicos Islands group: South Caicos Island and Grand Turk Island.

Etymology.

A geographic name formed from “Caicos,” the islands on which this subspecies has been found, and the Latin suffix "- ensis," meaning of or from that place.

Diagnosis.

This new subspecies is similar to the other six subspecific taxa of Tetracha sobrina , closest to Tetracha sobrina infuscata (Mannerheim), but differs in the reduced size of its apical lunules (narrow, more or less parallel-sided), green (not blue) elytral margins; small, round, basal trans-sutural coppery-red spot; and broad, black medial band.

Description.

( Figs 9-10 ). Length males (n=15) 13.3-15.8 mm; females (n=13) 14.1-16.4 mm. Most similar to Tetracha (Tetracha) sobrina infuscata (Mannerheim). All appendages pale except antennomeres 2-4 which have small distal brown spots opposite eyes and distal tips of femora which are infuscated. Clypeus and frons metallic green; vertex coppery, duller (South Caicos) to redder (Grand Turk), but never the bright red of Tetracha sobrina infuscata . Pronotum red with green highlights, especially the posterior transverse line, but again not the bright red of Tetracha sobrina infuscata . Elytra (excluding green punctures) with base with a small trans-sutural, rounded red spot; lateral margins, between the elytral base and the anterior tip of the apical lunule, clearly metallic green; the remainder of the elytra black, no violet areas toward the elytral apices; apical lunule narrow, parallel-sided, inner margin less distinct with scattered disjunct pale cells. Elytral sculpturing consists of punctation over basal half, pits deep blue-green; pits separated by smooth, shiny metallic surface, with very little trace of imbrications or granules; punctures are weakly aligned transversely; posteriorly, pits decrease in size and density while becoming increasingly imbricated, and merge into shingle-like transverse rows, especially between the apical lunules; pits and imbrications greatly reduced to absent on lunules.

Discussion.

The characters separating this subspecies are somewhat superficial ones of color and texture, but as this is largely all that separates the six described subspecies of this wide-ranging species (see Naviaux 2007), and as these characters seem to be relatively constant over large populations, it seems appropriate enough to describe these isolated island populations from the Turks and Caicos Islands as a new subspecies. The new subspecies is easily separated from five of the six currently recognized subspecies ( Naviaux 2007) by the very black color of the elytra, starting in front of the apical lunules and reaching more or less to the base along the suture, and by the relatively narrow and parallel-sided apical lunules. The other five subspecies all have bright metallic colors along the elytral suture, and broader, rounded apical lunules, in most individuals more comma-shaped or globular (these are three mainland subspecies ( Tetracha sobrina punctata (Laporte), Tetracha sobrina freyi (Mandl) and Tetracha sobrina guyanensis Naviaux), one subspecies both mainland and Lesser Antilles ( Tetracha sobrina sobrina (Dejean)), and one subspecies in the Lesser Antilles ( Tetracha sobrina antiguana Leng and Mutchler)). The most similar subspecies is Tetracha sobrina infuscata (Mannerheim) from Cuba, Hispaniola, Puerto Rico and the Virgin Islands. Our new subspecies differs from this mainly in the extent of the blackened center of the elytra, and in the shape of the apical lunules. Tetracha sobrina caicosensis has the elytra black from the apical lunules to at least the anterior third, and in many individuals more or less all the way to the base, and the green marginal band is very narrow. The apical lunules are narrow and usually parallel to the elytral margin; in some individuals somewhat broader, but still always narrower than in Tetracha sobrina infuscata , with the incision between the two lunules wider and the medial border much more jagged or irregular. Tetracha sobrina infuscata has the elytra blackened just in front of the apical lunules, but only in the apical third or so, becoming gradually more metallic green in the anterior two-thirds, and the green marginal band is broader. The apical lunules are very wide, with a relatively narrow incision between the two lunules, and with the medial border very sharply defined and regular.

Habitat and collecting notes.

At Victoria Salina on South Caicos Island, taken on the edges of dirt roads, mostly at a large open dry sandy area away from the wet salt flats. Cicindela boops and Cicindela trifasciata were taken nearby, but in moist saline areas. The Cicindela were taken mostly during the day, with a few at night; the Tetracha were all taken at night. At Saunders Pond on Grand Turk Island ( Fig. 11 ), taken at the edge of the pond and at damp saline areas, some with green algal mats. This is a much wetter habitat than Victoria Salina. A single Cicindela trifasciata was also taken.

Figures

Figure 11. Habitat of Tetracha sobrina caicosensis, Grand Turk

Figures 9 - 10. Dorsal habitus of Tetracha sobrina caicosensis; male, length 14.5 mm 9 female, length 16.0 mm 10.