Nesobasis malokuensium, Marinov & Rashni, 2025

Marinov, Milen & Rashni, Bindiya, 2025, A contribution to the Odonata fauna of Moala Island, Fiji. Part I: erection of three new species in genera Nesobasis Selys, 1891 and Nikoulabasis Ferguson et al., 2023 (Odonata: Coenagrionidae), Zootaxa 5637 (2), pp. 292-310 : 296-299

Nesobasis malokuensium sp. nov.

( Figs 4–8 )

Holotype. ♂ ( NZAC04231107 ), tributary of Wailevu creek above Maloku village, 18.5890S, 179.8744E, 212 m a.s.l., 6 May 2024, MM leg.

Paratypes. 1 ♀ ( NZAC04231081 ), same data as holotype ; 5♀♀ ( NZAC04231082 , USPac_14004–7), section of Wailevu creek about 500 m above Maloku village up to the Savukaratu waterfall, 18.5876S, 179.8741E to 18.5903S, 179.8744E, 151–260 m a.s.l., 4 May 2024, MM leg .; 2♀♀ ( NZAC04231079 , USPac_14008), Wailevu creek above the Savukaratu waterfall, 18.5910S, 179.8733E, 321 m a.s.l., 6 May 2024, MM leg .; 1♀ (USPsc_14003), Kedrau creek , native forested lowland stream by Keteira village, 18.6209S, 179.8890E, 17 m a.s.l., 23 October 2020, BR leg .

Allotype. ♀ ( NZAC04231078 ), section of Wailevu creek about 500 m above Maloku village up to the Savukaratu waterfall, 18.5876S, 179.8741E to 18.5903S, 179.8744E, 151–260 m a.s.l., 4 May 2024, MM leg.

Additional material: 1♂ ( FSCA), no locality, 13 July 1924, E.H. Bryan leg. (head and last five abdominal segments are missing) ; 1♂ 2♀♀, section of Wailevu creek about 500 m above Maloku village up to the Savukaratu waterfall, 18.5876S, 179.8741E to 18.5903S, 179.8744E, 151 to 260 m a.s.l., 4 May 2024, MM leg .; 1♂, Wailevu creek above the Savukaratu waterfall, 18.5910S, 179.8733E, 321 m a.s.l., 6 May 2024, MM leg .; 2♂♂, tributary of Wailevu creek above Maloku village, 18.5890S, 179.8744E, 212 m a.s.l., 6 May 2024, MM leg .

Etymology. These were the most common damselflies during the field sampling on Moala. The name is a combination of the name of the village Maloku with— ensium, a Latin morpheme (noun in the genitive case) denoting its inhabitants (= of the people of Maloku).

Description of holotype

( Fig. 4 )

Head ( Fig. 4B–C ). Labium pale yellow; frontal part of head green-yellow with weak bluish on genae, with dark restriction as follows: brown spot midway at posterior edge of labrum, same colour on dorso-lateral corners of labrum, black lines going parallel on anterior and posterior ends of postclypeus, connected with black bar at the middle; pale areas on genae going up to the level of the dorsal end of scape, on frons entering the black at level midway along scape outlining crown-like black spot in front of median ocellus; antennal segments as follows: scape same colour as the pale area of frontal part of head, pedicel and flagellum brown; remainder of head black on the dorsum save for yellow spot anteriorly of the median ocellus with the black going down to rear part of a yellow area close to the posterolateral corners of labium, weak pruinescence laterally on the dark area around the foramen; eyes discoloured, green in life with traces of brown dorsally and intensive light green to yellow-green ventrally ( Fig. 5 ).

Thorax ( Fig. 4A–B ). Prothorax pale blue-green on posterior lobe and black dorsally on middle and posterior except for a pale line along the posterior edge of posterior lobe; middle lobe pale blue-green laterally with dark line arching midway with yellow shades along edges. Pterothorax dark with slight green sheen occupying almost entire surface of mesepisternum save for yellow club-shaped marking on the ventro-anterior corner with very faint colour along dorsal carina, rest of thoracic capsule laterally almost entirely yellow with blue-green hue starting on disk of mesepimeron ventrally to level of metapleural suture, becoming pure yellow ventrally with dark spots as follows: transverse line close to the dorsal edge of mesinfraepisternum, black spot sitting on the metapleural suture close to posterior end, dark posteriorly on poststernum, faint spots around the dorso-anterior portion of mesepimeron and on track of interpleural suture. Legs: coxae yellow with faint blue on midlegs; trochanters yellow; femora yellow anteriorly and black on posterior faces following the same pattern—wide at junction with tibiae tapering toward the trochanters ending about 1/9 th before trochanter; tibiae yellow with brown at bases; tarsi and claws yellow with darker areas at the tips of the last segments; all segments of legs with hairs having black bases; mesostigmal plate roughly triangular in shape with terminal ends ventrally and dorso-posteriorly curved up and elevated from body, black on the disk outlined with pale along posterior edge.

Wings ( Fig. 4D ). Venation pale proximally to level of nodus, becoming darker distally; pterostigma dark with tiny pale line along the costal edge; FW: 13 Px, RP 2 at 6.5–7 th Px; HW: 12 Px, RP 2 at 6 th Px; arculus at 2 nd Ax in FW and slightly distal in HW.

Abdomen ( Fig. 4A ). Dark on the dorsum black on S1–2, S3–6 darker brown at the posterior 1/8 th of each segment, S7 black, S8 black with two blue spots, S9–10 almost entirely blue interrupted by a black line on dorsally on S10; terga pale starting half way laterally with colour as follows: S1 yellow anteriorly and blue posteriorly, S2 blue-green with slight yellow hue, S3 blue-green at the base and yellow posteriorly, rest of the segments yellow, same colour on the sterna with some black lines best pronounced on S7–8; pale colour on terga ascending dorsally along the anterior edge of segments of S3–7. Cerci ( Fig. 4E–F ) as long as the width of S10, approximately L-shaped in dorsal view, inner faces pale; paraproct dark brown, about 1/3 rd of the length of cerci with small horn-like projections curved towards each other. Penis ( Fig. 4G–H ) with distal segment T-shaped, lateral sides tapering towards the tip, laterally with a hump and the base and sloping distally.

Measurements: AL 32.5, HW 20.5, HF 2.5, S 0.2, P 0.4, MDBE 1.35.

Description of allotype

( Fig. 6 )

Similar in facies to male with pale colour more vivid blue.

Head ( Fig. 6B–C ). Almost identical to holotype with blue increased in intensity; pruinescence more intensive as well.

Thorax ( Fig. 6A–B, E ). Similar to holotype with blue increased in intensity and faint spots on mesepimeron and on track of interpleural suture lacking.

Wings ( Fig. 6D ). Venation generally identical to holotype; variations: pterostigma brown outlined with tiny line around the whole edge; FW: 13–14 Px, RP 2 at 6–7 th Px; HW: 12 Px, RP 2 at 6 th Px; arculus at 2 nd Ax in FW and slightly distal in right HW only.

Abdomen ( Fig. 6A ). Almost identical to holotype with the dorsum of the terga unicoloured black, sterna with dark longitudinal lines along the whole length and S10 unicoloured blue on the dorsum. Cerci ( Fig. 6F ) black, slightly longer than the tip of the valves of ovipositor, paraproct dark dorsally and pale ventrally; styli dark with pale tips.

Measurements: AL 31.0; HW 22; HF 2.5; S 0.2; P 0.4; MDBE 1.35.

Note. Figure 7 displays the live colouration a female; note the eyes with vivid green anteriorly and blue posteriorly. The juvenile male has a similar pattern as the adult, but with the pale areas on the body replaced by yellow only, and the eyes bicoloured light brown dorsally and green anteriorly and ventrally ( Fig. 8 ). This specimen was preserved in ethanol and not selected as a paratype but added to the additional material.

Variation within paratype series. Paratypes (all females) do not show great variation in the thoracic colour ( Fig. 9 ). The shape and width of the dorsal line on the mesinfraepisternum was found the be the most variable property of the specimens. It is mostly crossing the whole segment as a wavy bar (see also Fig. 7 for live colour), but also is sometimes restricted to an anterior spot. The two blue spots dorso-laterally at the posterior part of S8 are mostly circular, being reduced in size in one specimen and missing in another. Variations in wings—FW: 13–16 Px, RP 2 at 6–7 th Px; HW: 11–13 Px; RP 2 at 5–6 th Px.

Measurements: AL 27.5–32.0, HW 19.5–22.5.

Figures

FIGURE 4. Nesobasis malokuensium, holotype: A) habitus; B) head and thorax, dorsal and lateral view; C) head, frontal view; D) HW; E–F) appendages, dorsal and lateral views; G–H) penis, lateral and ventral views.

FIGURE 5. Nesobasis malokuensium, holotype: coloration of freshly killed specimen.

FIGURE 6. Nesobasis malokuensium, allotype: A) habitus; B) head and thorax, dorsal and lateral view; C) head, frontal view; D) HW; E) posterior end of prothorax and mesostigmal plate; F) ovipositor.

FIGURE 7. Nesobasis malokuensium, adult female in life.

FIGURE 8. Nesobasis malokuensium, juvenile male in life.

FIGURE 9. Nesobasis malokuensium, variations within the paratypes.