Platynectes mbaole, Hájek & Šťastný & Hendrich & Balke, 2023

Hájek, Jiří, Šťastný, Jaroslav, Hendrich, Lars & Balke, Michael, 2023, A review of the genus Platynectes from the Solomon Islands (Coleoptera: Dytiscidae: Agabinae), Acta Entomologica Musei Nationalis Pragae 63 (1), pp. 57-74 : 66-67

Platynectes mbaole sp. nov.

( Figs 5 , 12–13 )

Type locality. Solomon Islands, Guadalcanal, 0.5 km N of Mbaole, ca. 09°37.69′S 160°06.69′E.

Type material. HOLOTYPE: J ( ZSMG), labelled:ʻSalomonen:C-Guadalcanal, / 0.5 km N Mbaole, 2799 feet / S 09°37.69 E 160°06.69E / 2007 K. Mailautoka leg. [p] // HOLOTYPE J / PLATYNECTES / mbaole sp. nov. / J. Hájek et al. det. 2021 [p, red label]’. PARATYPES: 7 JJ 2 ♀♀, same label data as holotype, one specimen with additional label: ‘DNA / M. Balke / 2910’ [p, green label] ( JSCL, NMPC, ZSMG); 4JJ, labelled: ʻSOLOMON IS. / Guadalcanal [p] / 4724 [on side] Sutakiki R./ 5/4.[hw] 196 [p] 3. / 2,000’ [hw] / P.GREENSLADE [p] // SOLOMON IS: [red underlined] / Pres./ P.J.M.Greenslade. / B.M.1966-477 [p]’ ( BMNH, NMPC); 1 J 1 ♀, labelled: ʻSOLOMON IS.: [red underlined] / Guadalcanal Is. / Suta [ca. 9°41.5′S, 160°06.7′E] / 27.vi.1956 [p] // E.S.Brown / B.M.1957- 201 [p]’ ( BMNH).All paratypes with the respective red printed label.

Description. Male holotype. Habitus. Broadest in one third of elytral length; body outline continuous.

Colouration ( Fig. 5 ). Head with orange-brown clypeus and two small spots on vertex; appendages orange-brown. Pronotum with narrowly orange-brown sides and orange anterior corners; basal margin somewhat reddish translucent. Elytron black, disc with distinct yellowish pattern consisting of small basal spot in humeral area, subbasal spot, postmedial spot in two thirds of elytral length, two subapical spots and thin sublateral longitudinal line in apical half of elytra; humeral spot not connected with basal margin; subbasal spot round, situated approximately in two thirds of distance from suture to lateral margin; postmedial spot transverse, in centre narrowed, connected to sublateral line; subapical spots longitudinally elongate; sublateral line badly perceptible/interrupted in apical fifth of elytral length. Legs orange-brown, posterior legs somewhat darker than anterior two pairs. Ventral surface brown-blackish, prosternum and metacoxal processes brown.

Head ca. 0.63× width of pronotum, transversely elliptical. Meshes of reticulation mostly incomplete (not closed).

Pronotum. Reticulation similar to that of head; meshes somewhat larger and elongate, more often incomplete and less impressed on disc, becoming smaller, closed and deeply impressed near sides. Traces of microreticulation perceptible laterally close to sides. Centre of pronotal disc with small longitudinal furrow.

Elytra. Punctation double; coarse punctures present in two discal and two lateral, relatively distinct longitudinal lines; fine punctures occurring mostly on lines of reticulation. Reticulation similar to that of head and pronotum, consisting of heterogeneous polygonal meshes; meshes often elongate and incomplete. Microreticulation absent.

Ventral surface. Medial part of metaventrite with rather dense fine punctation. Ratio WC/WS = 4.7. Metacoxal lines incomplete anteriorly, slightly diverging. Metacoxal plates reticulated with polygonal meshes, punctation consisting of sparse fine punctures; plates with short longitudinal strioles. Abdominal ventrites with bunch of coarse setigerous punctures present in centre of ventrites III–V, additional setigerous punctures arranged sparsely in transverse line in medial part of ventrites.

Male genitalia. Median lobe ( Fig. 12a ) in lateral aspect slender medially, strongly broadened to prominent apex; apex setose on apico-ventrally. Parameres ( Fig. 12b ) narrowly triangular, slender, incised basally; dorsal surface densely setated; apical lobe long.

Female. Identical to male in habitus. Reticulation of dorsal surface more impressed, thus beetle appearing submatt; meshes on elytra less elongate, mostly closed.

Measurements. TL: 6.5–7.2 mm (mean value: 6.85 ± 0.15 mm); holotype: 6.9 mm. TL-h: 5.8–6.4 mm (mean value: 6.10 ± 0.15 mm); holotype: 6.1 mm. MW: 3.7–4.0 mm (mean value: 3.80 ± 0.10 mm); holotype: 3.8 mm.

Variability. The variability among the specimens of the type series can be seen only in shape and size of yellow markings: the humeral spot may absent completely and the subbasal spot is very small in some specimens, whereas additional two short longitudinal lines present posterior to elytral midlength close to suture in other specimen; sublateral longitudinal line in apical half of elytra may be complete.

Differential diagnosis. The new species can be recognized from all other Platynectes from the Solomon Islands by combination of large body size, distinctive dorsal surface pattern ( Fig. 5 ) and the shape of male genitalia with prominent apex of the median lobe ( Figs 12–13 ).

Etymology. The new species is named after its area of occurrence – Mbaole village, in the vicinity of which the new species was collected. The specific epithet is a noun in the nominative singular, standing in apposition.

Collecting circumstances. Unknown.

Distribution. The new species is known from medium altitude area (ca. 840 m) in north-central Guadalcanal ( Fig. 25A ).

Figures

Figs 4–6. Habitus of Platynectes in dorsal (a) and frontolateral (b) view. 4 – P.malaita sp. nov.; 5 – P.mbaole sp. nov.; 6 – P.owaraha sp. nov. Not to scale.

Figs 12–15. Male genitalia of Platynectes. 12 – P. mbaole sp. nov. (holotype); 13 – P. mbaole sp. nov. (paratype, Sutakiki); 14 – P. owaraha sp. nov.; 15 – P. popomanaseu sp. nov. a – median lobe in lateral view; b – parameres. Scale bar = 0.5 mm.

Fig. 25. Distribution of Platynectes species in the Solomon Islands (A) and Vanuatu (B).