Dythemis sterilis multipunctata Kirby, 1894

Meurgey, François & Poiron, Celine, 2011, The true Dythemis multipunctata Kirby, 1894, from the West Indies and proposed new taxonomic status (Odonata: Anisoptera: Libellulidae), Zootaxa 3019, pp. 51-62 : 56-58

Dythemis sterilis multipunctata Kirby, 1894 NEW COMBINATION

Figs. 1, 2, 5, 6, 8, 10, 12, 14, 16a, b

Dythemis multipunctata Kirby, 1894a:265 (descr. 3 St. Vincent); ― Clarcke, 1904: (catalog, St. Vincent, Grenada);― Donnelly, 1961:1 ( St. Lucia);― Donnelly, 1970: 5 ( St. Vincent, Grenada); ―Kimmins, 1968: 289 (lectotype 3 designated, BMNH, photos examined)― Woodruff et al., 1998: (catalog, bibliography, Grenada).

Dythemis multipunctata var.? Kirby, 1894a: 228 (mention. 3 Grenada); ―Kimmins, 1968: 289 (lectotype 3 designated, BMNH, photos examined)

Specimens examined. Total 14318Ƥ. ST. VINCENT: 234Ƥ, St. George Parish, Mountain Fairhall, Belair mineral spring, 31.V.2010, Meurgey leg. NHMN; 234Ƥ, St. George Parish, Argyle Beach, 6.VI.2010, Meurgey leg. NHMN; 132Ƥ, Arnos Vale Airport, Greathead Bay, Meurgey leg. NHMN; 1Ƥ, Kingstown Botanical gardens, 4.VI.2010, Meurgey leg. NHMN; 332Ƥ, St. David Parish, Wallibou river, 01.VI.2010, Meurgey leg. NHMN; 1Ƥ, St. David Parish, Troumaca Dam, 01.VI.2010, Meurgey leg. NHMN; 23, St. Andrew Parish, Vermont Nature Trail, 03.VI.2010, Meurgey leg. NHMN; 131Ƥ, St. Patrick Parish, Wallilabou Falls, 01.VI.2010, Meurgey leg. NHMN; 233Ƥ, Charlotte Parish, Mesopotamia valley, Montréal gardens, 7.VI.2010, Meurgey leg. NHMN.

Description. Head of male (Figs. 5, 16a) with eyes in life brilliant orange-red dorsally, with a bluish tinge ventrally. Face mostly white or yellow, densely covered with black hairs. Labium pale with broad black median band. Labrum pale with anterior margin black and two small spots on each side; anteclypeus pale whitish or yellow; postclypeus white or yellowish with black line on posterior margin; antefrons orange; postfrons metallic purple with white on each side; vertex metallic-purple; occipital triangle pale at apex, glossy purple with two yellow spots posteriorly. Rear of head with two yellow spots.

Prothorax obscure dark brown with anterior margin yellow, middle lobe with pair of yellow spots medially. Pterothorax (Figs. 1,16a) yellow and metallic black stripes as follows: a broad mesepisternal; a broad humeral; a narrow mesepimeral joining humeral at its middle; a broad metepisternal, a broad pleural, the latter bifid anteriorly with a small streak on metepimeron, rounded below and joining the metepisternal suture. All lateral thoracic stripes forming approximately a YIY design. Dorsum of thorax between wings always with a broad yellow longitudinal stripe. Venter of thorax yellow with two black spots anteriorly and a black transverse streak posteriorly. Wings hyaline, tinged with amber at base of forewings, apex brown-black. Ax Fw 12–13; Px Fw 7; Ax Hw 8–9; Px Hw 9. Legs black, with coxae yellowish; anterior coxae and femora white or yellowish beneath. Mesofemora with short, peg-like spines increasing in length from base to apex.

Abdomen (Figs. 1,16a) black, obscure dark brown, yellow on the ventral side of S2–8, and pale as follows: S2 mostly yellow with a black spot on dorsum, S3 with two ventrolateral yellow spots along tergal margin, and two yellow dorsolateral yellow spots. S4–7 dorsally with two yellow spots basally, followed by two yellow streaks, those of S6 the smallest (often absent), those of S7 the widest occupying the basal half of the length of the segment. S8–10 black, except for a thin yellow line bordering each segment distally. Abdomen nearly triquetral. Genital lobe rounded with a central impression covered with black hair. Hamules nearly straight and directed downward, at midlength slightly curved posteriad and with a slender, rounded tip (Fig. 8). Cerci (Figs. 10,12) black, ventrally with row of 4–5 denticles, last two longest. Epiproct yellow, black on margins.

Female with head as in male but antefrons mostly orange, postfrons and vertex metallic-blue (Fig. 6). Thorax (Figs. 2,16b) as in male. Wings similar to male; Ax Fw 12–13; Px Fw 8–9; Ax Hw 8–10; Px Hw 8–10. Legs as in male except for mesofemoral spines. Abdomen (Figs. 2, 2b) as in male but S4–7 dorsally with two yellow spots basally, followed by two broad yellow streaks, those of S6 the smallest, those of S7 the widest, occupying basal 2/ 3 of segment. Caudal appendages black, longer than S10. Vulvar lamina black, deeply cleft, with divergent margins (Fig. 14).

FIGURE 16.

Dimensions. Males (n = 14): Total length 29.0–39.0, abdomen 26.0–28.0, Fw 27.0–29.0, Hw 27.0–29.0. Females (n = 18): Total length 31.0–32.0, abdomen 25.9–26.2, Fw 27.8–28.0, Hw 27.8–28.8.

Distribution. Endemic to St. Vincent, Lesser Antilles, intergrading into D. s. sterilis northward through St. Lucia and Martinique.

Remarks. The relationship of D. multipunctata to D. sterilis is unclear, and correct assignment of this taxon is problematic. We have taken a conservative approach and have chosen to treat D. multipunctata as a subspecies of D. sterilis , though we acknowledge that further analysis including molecular studies may show the Lesser Antillean populations to represent a separate species. Lesser Antillean populations of Dythemis sterilis vary more than do their mainland counterparts as follows: D. s. multipunctata ( St. Vincent; 13°13' N) possess metallic coloration on the vertex and, uniquely so, on the postfrons, and the dark body coloration is dark brown as in D. nigra . Populations from St. Lucia (13°53' N), immediately north of St. Vincent, have an all dark body coloration as in D. s. multipunctata but the metallic coloration is confined to the vertex. Specimens from Martinique (14°35' N) have a dark thorax with a red to red-brown vertex sometimes with a pearly sheen of blue. Specimens from Dominica (15°25' N) and Guadeloupe (16°2' N) have no metallic coloration on the frons and vertex, and the body coloration is brown as in typical D. s. sterilis from the mainland. The only difference we have observed for males from these two localities is the dark brown genital lobe; this structure is entirely pale in mainland populations of D. s. sterilis and also in males from St. Vincent and St. Lucia, although the ventral margin of the lobe may be dark brown in some males from the latter island. Thus, D. s. multipunctata seems to intergrade toward typical D. s. sterilis from St. Vincent north through Guadeloupe. Specimens from Barbados (12°6' N) resemble those from St. Lucia and Martinique and tend to approach typical D. s. sterilis as seen in Tobago (11°14' N) and Trinidad (10°27' N). Our reluctance to accord specific status for these populations is due to clinal variation toward typical D. s. sterilis both north and south of St. Vincent.

Ecology. As stated by Kirby (1894), Dythemis s. multipunctata frequents lentic habitats in open areas, such as swamps, seepages, slow-flowing lowland streams, generally with muddy beds, between sea level and approx. 200 meters altitude. Away from water, fully mature and teneral individuals can be found hawking along clearings and mountain tracks or roads. At breeding sites, males generally perch on the tip of plant stems or on top of bushes. Females fly inconspicuously under forest cover near the shoreline. Co-occurring Odonata include Argia telesfordi Meurgey , Erythrodiplax umbrata (Linné) and Orthemis sulphurata Hagen. Kirby (1894) misidentified the following species from St. Vincent and Grenada: Argia insipida = Argia telesfordi ; Argia sp. = probably Argia telesfordi as this species is the only Argia present on both islands; and Micronympha senegalensis = Ischnura ramburii Selys. Kirby also mentioned a Coenagrion sp. from Grenada. This genus is not known from the Lesser Antilles, and we do not know to what species it could refer.