Vanuatubasis bidens (Kimmins, 1958)

Saxton, Natalie A., Marinov, Milen G. & Bybee, Seth M., 2022, Revision of Vanuatubasis Ober & Staniczek, 2009 (Odonata, Coenagrionidae), with description of seven new species, ZooKeys 1128, pp. 129-169 : 129

Vanuatubasis bidens (Kimmins, 1958)

Figs 2 , 20A , 21A

Nesobasis bidens Kimmins, 1958: 239-241 (species description); Ober and Staniczek 2009: 490-492; Marinov et al. 2019: 14.

Material examined.

Holotype. (1 ♂ NHM) “Type” " NEW HEBRIDES:| Aneityum. | Red Crest: 1,200ft. [sic] | 3m. N.E.of Anelcauhat. | vi.1955." " L.E.Cheesman. | B.M.1955-217." "Nesobasis | ♂ bidens Kim | D.E.Kimmins det. 1957 | TYPE.".

Additional material.

(3 ♂♂, 3 ♀♀ BYU) " Vanuatu: Aneityum : | Anijemhag River, 12.v.2017 | 20.2180°S 169.8012°E, coll. | S.M.Bybee, M.Marinov " Vanuatubasis bidens was known by males only. Here we describe the female .

Description of female.

Head: Labium overall pale beige; labrum pale green, darkening posteriorly, with dark brown postero-lateral edges and medially, a black spot at posterior edge; anteclypeus, genae, and mandibles (except for reddish tips) greenish yellow; postclypeus greenish yellow medially, with a black bar that begins medially and extends to the anterior edge, not extending to anterior corners; frons yellow, abruptly changing to black posteriorly; scapes and pedicels black, flagella dark brown and lightening apically; vertex and rear of head black, with bronze shimmer and white pruinescence; three pale ocelli with beige patch apical of the median ocellus; eyes cream-colored, although likely different color in life.

Thorax: Prothorax dorsally black with bronze shimmer; laterally yellowish green; pronotum black medially with greenish yellow edges, postero-lateral corners rounded to obtuse angles and weakly explanate, hind lobe raised and slightly curved outward medially, extending to point that protrudes posteriorly; mesostigmal plate black with green lateral edges, roughly triangular and staying approximately level across the outer surface. Pterothorax with black carina; laterally, mesepisternum with black stripe reaching the dorsal carina and reaching the mesopleural suture posteriorly across ~ 0.5 mm, but only reaching ~ 2/3 of the mesepisternum on the anterior and medial portion; yellow stripe located on anterior 1/3 of mesepisternum, not quite reaching mesinfraepisternum, and extending just past the mesopleural suture; mesepimeron overall pale green with yellow extending down from mesepisternum, short, dark brown line on posterior end of interpleural suture; metepisternum overall pale green with short, black line located on metapleural suture near the base of the wings, extending ~ 1/6 the suture’s length; mesinfraepisternum yellow-green with small, dark-brown spot located medially; metepimeron pale green and turning beige dorsally; coxae, trochanters, and femora dorsally pale brown and ventrally pale beige with black spines; tibiae pale brown with slightly darker, and smaller, spines than that of the femora; tarsi beige with dark brown edges and smaller spines; pale brown tarsal claws that darken apically to reddish tips, claws with a small tooth located on the basal 1/4 of their length.

Wings: Hyaline; venation dark brown; pterostigma elongated rhomboidal dark brown and lightening towards the edges; CuP approximately halfway between antenodals in all wings; arculus originates slightly distal of second antenodal crossvein in all wings; discoidal cells unequal with FW dorsal edge being 1/2 as long as HW. Nodal index: 14/2-2/13 in FW and 13/2-2/12 in HW.

Abdomen: Overall, yellow with black dorsal stripe, that lightens laterally, extending from S1-9, dark brown lines encircling the posterior end of S1-S5, and pale brown setae; S1 with anterior 1/2 beige and latter 1/2 pale green; S2 pale green; S3-S8 laterally yellow; S9 yellow, with dorsal stripe extending ¾ of lateral view posteriorly; S10 laterally blue with brown edges, dorsally with blue patch extending ¾ of its length. Ovipositor overall pale yellow and reddish brown ventrally; stylus rounded, dark brown and lightening apically; gonapophysis reddish brown. Cerci roughly triangular, brown, and narrowing to a slightly rounded apex.

Measurements (mm): total length 35-36 mm, abdomen 29-30 mm, HW 21-22 mm (n = 3).

Diagnosis.

Male. Vanuatubasis bidens can be distinguished from other known species of Vanuatubasis by a black pterostigma, bright blue abdominal S9 and S10, relatively straight black cerci that only curve medially on their apical 1/3, the presence of cercal teeth (although difficult to see in some specimens), and by having the lateral lobes of the genital ligula covering the sclerotized portion of the first genital segment. Female. Vanuatubasis bidens can be distinguished from other females in this genus by green thoracic coloring, and pale colored cerci surpassing the length of the stylus.

Variation.

Male. The sinusoidal shape of the cerci is not as pronounced in some individuals nor are the cerci “teeth” as prominent. Color varies from yellow to green, likely due to the maturity of the specimen. Female. Variation in color due to maturity of specimens, yellow immatures and green mature. Terminal ends of cerci are sometimes more pointed than that of the description above.

Distribution.

Aneityum, Vanuatu.

Notes.

This species was previously only known from one male. Here, we expand the number of known males collected as well as confidently associate the female. Kimmins (1958) noted that the holotype of this species, described as having yellow thoracic coloring, was likely an immature specimen but only had a single specimen and could not confirm this hypothesis. Additional collection efforts have confirmed Kimmins’ hypothesis and found that the mature individuals are green and immature individuals are yellow (see Marinov et al. 2019: fig. 9).

Figures

Figure 2. Vanuatubasis bidens (♂ BYU) A dorsal thorax B lateral terminalia C dorsal terminalia D lateral habitus V. bidens (♀ BYU) E dorsal thorax F lateral terminalia. Scale bars: 0.5 mm.

Figure 20. Male dorso-posterior and dorsal terminalia of A V. bidens B V. evelynae C V. insularivorum D V. kapularum E V. malekulana F V. nunggoli G V. santoensis.

Figure 21. Female face and dorsal terminalia of A V. bidens B V. discontinua C V. evelynae D V. insularivorum E V. kapularum F V. malekulana G V. nunggoli H V. rhomboides I V. santoensis J V. xanthochroa.