Vanuatubasis bidens ( Kimmins, 1958 ) Ober & Staniczek, 2009

Ober, Stefan V. & Staniczek, Arnold H., 2009, A new genus and species of coenagrionid damselflies (Insecta, Odonata, Zygoptera, Coenagrionidae) from Vanuatu, Zoosystema 31 (3), pp. 485-497 : 490-492

Vanuatubasis bidens ( Kimmins, 1958) n. comb. ( Fig. 4A, D, G, J )

Nesobasis bidens Kimmins, 1958: 239-241 , figs 1, 2a, b.

HOLOTYPE. — Vanuatu. Tafea Province, Aneityum, 3 miles NE of Anelcauhat, Red Crest , 1200 ft, VI.1955, leg. L. E. Cheesman, ♂ ( BMNH).

LABELS. — Holotype: Type ; NEW HEBRIDES:/ Aneityum./ Red Crest. 1,200ft. / 3m. N.E.of Anelgauhat./ vi vii 1955.; L.E.Cheesman. / B.M.1955-217.; NesobasIs / ♂ bIdens KIm/ D.E.Kimmins det.1957/ TYPE.

ADDITIONAL MATERIAL. — Not available.

DISTRIBUTION. — The species is only known from the type locality.

REDESCRIPTION OF THE HOLOTYPE

Preserved dry, pinned. In good condition, but right foreleg and left hind leg missing. Right forewing and abdomen between segments 6, 7 and 8 glued.

Head

Labium pale fulvous; labrum dark fulvous, with a small, central dark brown spot at the basal margin; genae, anteclypeus, and postclypeus dark fulvous, postclypeus with a denoted dark brown T-mark; frons brown; antennae brown, inner side of each scapus blackish; vertex and occiput black except for a small brown spot in front of the median ocellus; rear of head brownish; eyes dark brown.

Thorax

Prothorax dorsally bright black, laterally fulvous; hind lobe of pronotum rounded, prominent, with distinct, fulvous median keel connecting upper and inconspicuous lower pronotal hind ridge. Synthorax: mesanepisternum with shiny black median band reaching the mesopleural suture in its hindmost fourth, but elsewhere separated from it by a narrow, pale fulvous band, dorsal carina brown; mesostigmal lamina slightly triangular, anterior and posterior ridge convergent and ending in a protuberance, posterior rim with small median tubercle; mesokatepisternum fulvous with dark brown spot in its upper half; mesepimeron fulvous; metanepisternum fulvous, posteriorly with two small, elongate, brown spots at the intersegmental and metapleural suture; metakatepisternum fulvous; metepimeron fulvous becoming yellowish posteriorly; poststernum yellowish, posterior margin black; sternum yellowish.Legs yellowish, basal inner surface of protibia brownish; spines dark brown.

Wings

Hyaline; venation dark brown; pterostigma brownish with narrow pale margin, less than one cell long, rhomboidal; 15/14 postnodal crossveins in forewings and 13/12 postnodal crossveins in hind wings.

Abdomen

Segments 1 and 2 yellowish, dorsally brown to dark brown; segments 3-6 yellowish, dorsally light brown to brown, dorsal brown colouration extending downwards at the posterior part of each segment but missing anteriorly, there the yellowish colouration reaches the dorsal carina in a spot of almost triangular shape; on segment 7 the yellowish colouration turns creamy and the brown colour gets darker and extends posteriorly to form a dark triangle as seen in lateral view, brown of segments 1-6 with a slight greenish metallic shimmer getting bronze on segment 7; segment 8 with the exception of a narrow creamy line on the lower lateral border dark brown to blackish with a metallic sheen; the colouration of segment 9 is divided in a ratio of 5:3, being bluish-white in the upper, and brown in the lower part; segment 10 almost entirely bluish-white, only ventrally a bit creamy.Superior anal appendages short, in dorsal view broad and ovate, upper surface slightly concave, dark brown, lateral part paler, the apical margins with two small, acute, shiny black teeth, one at the inner angle, the other just in the centre ( Fig. 4A, D ); in lateral view the inner tooth appears as an elevated knob; lateral part of superior anal appendages bulged ( Fig. 4G, J ); in posterior view the appendages are straightened diagonally, forming a rounded roof. Inferior anal appendages in dorsal view forceps-like, but only slightly incurved, ending in black tips which are directed inwards, about two and a half times as long as the superior appendages ( Fig. 4A, D ), yellowish-white at base, forceps brown to dark brown; in lateral aspect broad at base, abruptly narrowed to an acute apex ( Fig. 4G, J ). In posterior view a small protuberance is visible basally on the inner side of each appendage.

Measurements

Length of abdomen: c. 35 mm (not completely elongated), length of left hind wing: 22.1 mm, length of right hind wing: 21.8 mm.

VARIATION

The species is only known from the holotype.

REMARKS

Due to the colouring it is likely that the specimen is immature. A comparison with the original description ( Kimmins 1958) reveals that the colouration has lost its intensity over the last 53 years. According to Kimmins (1958) it could be quite possible that the yellowish-fuscous areas become bluish or greenish during the maturation process. Males of V. bidens n. comb. can be easily distinguished from males of the other two species of the genus by the bidentate apical margins of the superior anal appendages. These appendages appear in the dried specimen in a very upright position, in life, they may be in a more oblique position. The length of the abdomen was stated by Kimmins (1958) as 25 mm, this seems to be a literal error.

Figures

FIG. 4. — A, D, G, J, Vanuatubasis bidens (Kimmins, 1958) n. comb., holotype,♂ (BMNH), anal appendages in dorsal and lateral view; B, E, H, K, V.malekulana (Kimmins,1936) n. comb.,holotype,♂ (BMNH),anal appendages in dorsal and lateral view;C, F, I, L, V.santoensis n. gen., n. sp., holotype, ♂ (SMNS: ODO 000242 K), anal appendages in dorsal and lateral views. Scale bars: 0.2 mm.