Tetracha (Neotetracha) naviauxi, 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 : 87-93

Tetracha (Neotetracha) naviauxi sp. n. Figs 1, 2 4 -8

Type Material.

(38 specimens) Holotype ♂: "TURKS & CAICOS/ ISLANDS, Salt Cay-/ N. Creek Salina/ 21°19.6'N, 71°12.2'W / D. Brzoska 9-I-2010" (CMNH). Allotype ♀: same data as holotype (SEMC). Paratypes (36) as follows: 20 same data as holotype (9 ♂♂, 4 ♀♀ DBC; 1 ♂, 1 ♀ CMNH; 2 ♂♂ FSCA; 2 ♂♂ RNC; 1 ♂ SEMC); 10 labelled: "TURKS & CAICOS/ ISLANDS, Salt Cay-/ Pilchard Hole Salina, 1m/ 21°18.7'N, 71°12.8'W / D. Brzoska 9-I-2010" (7 ♂♂ DBC; 2 ♂♂ AMNH; 1 ♂ CMNH); 6 labelled: "TURKS & CAICOS/ ISLANDS, Salt Cay-/ near airport/ 21°20.0'N, 71°12.3'W / D. Brzoska 9-I-2010" (4 ♂♂, 1 ♀ DBC; 1 ♂ CMNH).

Additional material.

(1 specimen) "Turks & Caicos Isls./ South Caicos Isl./ February 11, 1953/ / Van Vost--A. M. N. H./ Bahama Isls. Exped./ Coll. E. B. Hayden" (1 ♂ AMNH).

Type locality.

Salt Cay, Turks & Caicos Islands group.

Distribution.

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

Etymology.

A Latinized eponym, genitive case, based on the surname of Roger Naviaux.

Diagnosis.

This species is easily distinguished from other Caribbean Tetracha by the relatively broad and squat elytra ( Figs 1-2 ) with somewhat arcuate sides (elytra slenderer and longer with sides parallel in other species); the very weakly projected humeral angle; the reduced metathoracic wings (less than the length of an elytron, without reflexed apex); and the narrowly rounded, subacute elytral apex, whose apical extremity is some distance from the suture (similar only in Tetracha acutipennis (Dejean)( Fig. 3 ) and Tetracha misella Naviaux, in which the elytral apex is drawn out into a spine or sharp point; other species have broadly rounded apices curving shallowly into the suture).

Description.

( Figs 1-2 ). Length (n=15) males 11.9-14.6 mm; females (n=7) 13.4-14.6 mm. Small-sized, robust Neotetracha . Head and pronotum dorsally metallic blue-green, anterior margin of pronotal collar black to ferruginous; elytra bright metallic blue to blue-green for most of length, blackish-green between apical lunules; ventral surface metallic green on head, prothorax and laterally on sterna II-IV; center of sterna III-IV, all of sternum V, most of sternum VI, and medial base of sternum VII brown; posteriolateral corner of sternum VI and broad band along posterior margin of sternum VII pale; antennae, palpi, mandibles, labrum and legs mostly pale (coxae brunneus). Head, thorax and abdomen glabrous except for usual fixed setae, fringes of cleaning setae along anterior and posterior margins of prothorax, and elytra with a subsutural row of minute setigerous punctures and a few basal and humeral setae.

Head. Left mandible of male ( Fig. 4 ) with four teeth, apical tooth and first terebral tooth elongate, subequal in length, apical tooth deflexed ventrally, terebral teeth of decreasing size, third terebral tooth basally anastomosed to second; right mandible of male ( Fig. 4 ) with elongate apical tooth and two broad incisor-like terebral teeth, apical and first terebral tooth deflexed ventrally. Left mandible of female ( Fig. 5 ) with apical tooth elongate, slightly deflexed ventrally, first and third terebral teeth shorter than second, third terebral tooth anastomosed to second; right mandible ( Fig. 5 ) similar to that of male. Basal molars of each mandible with tuft of setae at base. Mandibular scrobes shallow, without setae or setal pores, dorsal edge rounded nearly to base. Labrum with four submarginal setae; labrum short, sides subparallel, anteriolateral angles rounded, posterior margin shallowly V-shaped; labrum of male narrow with four small subequal teeth; female with teeth more sharply defined, medial pair anteriorly produced. Clypeus narrow, chevron-shaped, laterally depressed. Tentorial pits deep, fronto-clypeal suture effaced between pits, evident laterally, bisetose; two supraorbital setae over each eye connected by shallow groove paralleling the eye; frontal suture weakly indicated by pair of elongate depressions. Frons and vertex mostly smooth, vertex sculptured with web of very shallow irregular “cracks.” Microsculpture of frons and vertex irregularly isodiametric (weakest near eyes). Eyes large, convex. Antennae entirely testaceous except for dark spots toward apices of antennomeres 2-4; antennomeres 1-4 without dorsal carina. Mentum with median lobe acute, lateral lobes not strongly acuminate; ligula bisetose.

Thorax. Pronotum strongly convex, cordiform; anterior transverse impression weak medially; median longitudinal impression shallow, extended to anterior margin; posterior transverse impression deep with triangular lateral basal impressions at the posteriolateral corners; anterior collar with shallow impressed transverse submarginal line extended to anteriolateral corner but effaced medially; posterior collar with marginal line effaced medially. Notopleural suture deep; anterior corner of proepisternum separates pronotum from prosternum; proepisternum with a few large shallow punctures in posterioventral corner. Coupling sulcus of female a shallow groove along mesopleural suture from mesocoxa to humerus, with trace of small pit under humerus.

Legs. Pro- and mesotrochanters with small subapical setigerous punctures. Males with protarsomeres 1-3 with full tarsal pads, protarsomeres 2-3 asymmetrical.

Elytra. Elytra relatively short and broad compared to combined length of head and thorax, gently curved laterally from humerus to apex, widest at middle; humerus rounded and weakly projected, less protruded than in related species; apex obtusely angulate with angle evenly rounded, not acuminate, oblique to terminus of sutural line, apical extremity quite some distance from suture; apex without microserrulation. Apical lunules narrow, parallel-sided, attaining elytral suture. Anterior half of elytron with well spaced, large, deep pits (distance between pits 1-3 times diameter of average pit), each with a small reflective spot and minute irregularity at the bottom, pits irregular without tendency to form rows; posterior half with smaller punctures rapidly decreasing in size and becoming impunctate proximal to apical lunules; elytral surface flat and smooth between punctures, lacking imbrications, surface somewhat shiny.

Metathoracic Wings. Wings reduced to a narrow elongate pad about 3/4 length of an elytron.

Abdomen. Sterna IV-VI each with pair of ambulatory setae. Sternum VII broadly and deeply notched medially in male, small shallow medial emargination in female.

Aedeagus. ( Figs 6-7 ). Elongate and slender, broadest at middle, apically drawn out to blunt, rounded tip; apex long and narrow, slightly deflexed.

Variation.

The single specimen from South Caicos Island differs in a few minor details from the series from South Cay, and we have therefore left it out of the type series. Whether these details have any significance will have to wait for a more robust sample and a better understanding of which islands are inhabited by the species. Though there is some variation, all the specimens from South Cay are a greenish-blue, whereas the South Caicos individual is a bright dark blue. The border between the dark elytron and its apical lunule is slightly jagged and diffuse in the South Cay specimens, whereas the border is much smoother and more sharply defined in the South Caicos individual.

Dedication.

We take great pleasure in naming this remarkable and beautiful new species after our friend and colleague Roger Naviaux in recognition of his many years of fine work on tiger beetles, and in particular in recognition of his excellent monograph of Tetracha ( Naviaux 2007).

Discussion.

Tetracha naviauxi fits into the Tetracha acutipennis group as defined by Naviaux (2007: 80). Characters are similar in the conformation of the mandibles, the shape of the labrum, the dorsal coloration (green foveae), the shape of the apical lunule, the deep non-granular punctures with reflective spot at the base of each and smooth surface around each puncture, the third protarsomere slightly asymmetrical, the long slender shape of aedeagus, and the internal sclerites of the aedeagus. Most important, the structure of the elytral apex is similar: the elytral apex is narrowly rounded at some distance from the suture, and thence curved forward to the suture leaving a relatively broad incision between the two elytra. Tetracha naviauxi ( Figs 1-2 ) differs from the other two species in this group ( Tetracha acutipennis ( Fig. 3 ) and Tetracha misella ) most obviously by its gestalt. The latter two species have longer, slenderer, parallel-sided elytra with the apex drawn out into a spine or at least an acute angle, whereas Tetracha naviauxi has shorter, broader elytra with the sides gently arced from humerus to apex, and the apex is at most subacute without a spine. All specimens of Tetracha naviauxi have reduced metathoracic wings, narrow and shorter than the elytron, without reflexed apex, with the accompanying reduction of the length of the metepisternum and a weak, barely projected humerus; in Tetracha acutipennis and Tetracha misella , all known specimens are fully winged, with a slightly longer metepisternum and a much stronger, more projected humerus. Tetracha naviauxi has sparser, deeper, larger elytral punctures, which disappear relatively abruptly in the apical third; elytral punctures in the other two species are denser, shallower, smaller, and reduced in size in the apical third but present nearly to the apex. The coupling sulcus of female Tetracha naviauxi is shallower, less abruptly angled against the mesepisternum, and ends laterally under the humerus in only a trace of a small pit; female Tetracha acutipennis have a deeper and more sharply angled sulcus ended laterally under the humerus in a pronounced pit (we have not seen the sulcus for Tetracha misella , but presumably it is similar to Tetracha acutipennis as Naviaux does not mention any difference). The aedeagi of Tetracha naviauxi and Tetracha acutipennis are similarly shaped, with internal sclerites in the same positions and only minor differences in shape. The external aedeagal tube of Tetracha acutipennis is, however, considerably more elongate than that of Tetracha naviauxi , especially both basally and apically compared with the swollen central bulb; this is most easily seen at the apex, where Tetracha acutipennis tapers to a longer and slenderer point, whereas Tetracha naviauxi is shorter, thicker, and with the tip slightly thickened and curved.

This is so far as we know the only short-winged tiger beetle known from the Caribbean region. The structure of the humeral region, the metathoracic plates and the elytra suggests that the species is always short-winged, and that it is unlikely that fully-winged individuals might occur from time to time. Loss of flight has certainly curtailed its ability to disperse and in part accounts for its limited distribution on these remote islands.

We include here a modified version of Naviaux’s (2007: 80) key to species groups of Neotetracha to accommodate the new species.

2	Mandibles of male not or moderately forked; elytral apex rounded into suture at an obtuse angle	5
-	Mandibles of male deeply and broadly forked, the first terebral tooth approximately of same length as the apical tooth; elytral apex narrowly rounded and subacute or spined distant from the suture OR broadly rounded into suture at a right angle	6
6	Elytral apex narrowly rounded and subacute or acuminate, apical extremity distant from suture	acutipennis group 6'
-	Elytral apex broadly rounded into suture at a right angle, apical extremity much closer to suture	13
6'	Elytral apex narrowly rounded or subacute, but without sharp angle or acuminate spine; elytra broader, shorter, with sides gently curved from humerus to apex; humerus less protruded; elytra punctation coarser, sparser, deeper, weak or absent in apical third; metathoracic wing reduced; Turks and Caicos Islands	Tetracha naviauxi new species
-	Elytral apex forming an acute angle or acuminate spine; elytra slenderer, longer, with sides parallel; humerus more strongly protruded; elytra punctation smaller, denser, shallower, weaker but still obvious and present over most of apical third; Greater Antilles	6 ’’
6 ’’	Elytral apex less rounded, drawn into a long point; length 13-15.5 mm; Hispaniola and Cuba	Tetracha acutipennis (Dejean)
-	Elytral apex more rounded, drawn into a short point; length 10.5-12.6 mm; Haiti	Tetracha misella Naviaux

Habitat and collecting notes.

At North Creek Salina on Salt Cay, taken mostly on moist salt flat covered with a dark algal mat surrounded by Salicornia . At Pilchard Hole Salinas, taken on damp salt flats. At the airport site ( Fig. 8 ), taken at a small salt pond and adjacent flats. All three sites also had Cicindela boops and Cicindela trifasciata . The latter were taken mostly during the day with a few at night, but all Cicindela naviauxi were taken at night.

Figures

Figure 3. Dorsal habitus of Tetracha acutipennis female, length 14.8 mm

Figure 8. Habitat of Tetracha naviauxi, Salt Cay, airport

Figures 1 - 2. Dorsal habitus of Tetracha naviauxi; male, length 13.5 mm 1 female, length 14.1 mm 2

Figures 4 - 5. Mandibles of Tetracha naviauxi, male 4 female 5

Figures 6 - 7. Male genitalia of Tetracha naviauxi, left lateral view 6 right lateral view 7