Platynectes makira, 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 : 63-65

Platynectes makira sp. nov.

( Figs 3 , 10 )

Type locality. Solomon Islands, Makira, Bweinaniawariki-apu, ca. 10°34.4′S, 161°51.8′E.

Type material. HOLOTYPE: J ( BPBM), labelled: ‘SOLOMON IS. / San Cristoval / Bweinaniawariki- / apu, 11.VIII.1960 [p] // C. W. O’Brian / Collector [p] // HOLOTYPE J / PLATYNECTES / makira sp. nov. / J. Hájek et al. det. 2021 [p, red label]’. PARATYPES: 7 JJ 8 ♀♀, same label data as holotype ( BPBM, NMPC, ZSMG); 2JJ 3♀♀, ‘SOLOMON IS. / San Cristoval / Wugiroga / 9.VIII.1960 [p] // C. W. O’Brian / Collector [p]’ ( BPBM).All paratypes with the respective red printed label.

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

Colouration ( Fig. 3 ). Head with orange-brown clypeus and two small spots on vertex; appendages orange-brown. Pronotum with broadly orange-brown sides and anterior corners; basal margin somewhat orangish translucent. Elytron black with brownish lateral margin and epipleura, disc with fairly distinct yellow-orange pattern consisting of two subbasal spots, one postmedial spot in two thirds of elytral length, two narrow subapical spots and band along lateral margin; first subapical spot small, indistinct, placed very close to base near scutellum; second subbasal spot larger and more distinct, placed sublaterally and more posteriorly than first spot; postmedial spot transverse, medially narrowed with posterior margin distinctly concave; preapical spots in form of two longitudinal, short, narrow bands; lateral longitudinal band continuous, starting as fairly distinct humeral spot, rather indistinct subbasally and apically. Fore and middle legs orange-brown, hind legs darker, brown. Ventral surface with brown head, prosternum and mesoventrite; metaventrite, metacoxal plates and abdominal ventrites darker, brown-blackish; apical ventrite orange-brown medio-posteriorly.

Head ca. 0.64× width of pronotum. Meshes of reticulation mostly incomplete (not closed).

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

Elytra. Punctation double; coarse punctures present in two discal and two lateral longitudinal lines; fine punctures occurring mostly on lines of reticulation. Reticulation similar to that of head and pronotum but slightly less impressed, consisting of heterogeneous polygonal meshes; meshes often incomplete. Traces of microreticulation hardly perceptible in apical third of elytra.

Ventral surface. Medial part of metaventrite with sparse fine punctation. Ratio WC/WS = 4.55. Metacoxal lines incomplete anteriorly, almost parallel-sided. Metacoxal plates reticulated with polygonal meshes; surface with short longitudinal strioles; punctation consisting of sparse fine punctures. 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. 10a ) in lateral aspect almost equally broad throughout its length; apex broadly rounded, distinctly setose on ventral side. Parameres ( Fig. 10b ) narrowly triangular, slender, incised basally; dorsal surface densely setated; apical lobe long.

Female. With elytral reticulation slightly more impressed, traces of microreticulation perceptible also laterally on pronotum and elytra.

Measurements. TL: 6.0– 6.1 mm (mean value: 6.05 ± 0.05 mm); holotype: 6.1 mm. TL-h: 5.3–5.5 mm (mean value: 5.40 ± 0.05 mm); holotype: 5.45 mm. MW: 3.3–3.5 mm (mean value: 3.40 ± 0.05 mm); holotype: 3.45 mm. Variability. Minor variability can be seen in elytral colouration of the type specimens: lateral band distinct throughout its length, postmedian lateral spot connected with lateral band in some specimens; and in extent of area on elytra with the traces of microreticulation perceptible.

Differential diagnosis. Larger (6.0– 6.1 mm) and more ovoid of two Platynectes species currently known from Makira Island. In addition, P. makira sp. nov. differs from the similar P. owaraha sp. nov. in the reticulation of pronotum reduced on centre of disc to punctures connected with short lines; in different elytral colouration which comprising two subbasal spots and long lateral longitudinal band extending to base of elytra (cf. Figs 3 and 6 ); and in male median lobe, which is almost equally broad throughout its length in lateral view ( Fig. 10 ).

Etymology. The new species is named after its area of occurrence – Makira Island, also known as San Cristobal. The specific epithet is a noun in the nominative singular, standing in apposition.

Collecting circumstances. Unknown.

Distribution. The new species is so far known only from two close localities in the mountainous central part of Makira Island ( Fig. 25A ).

Figures

Figs 1–3. Habitus of Platynectes in dorsal (a) and frontolateral (b) view. 1 – P. barana sp. nov.; 2 – P. lunga sp. nov.; 3 – P. makira sp. nov. Not to scale.

Figs 8–11. Male genitalia of Platynectes. 8 – P. barana sp. nov.; 9 – P. lunga sp. nov.; 10 – P. makira sp. nov.; 11 – P. malaita sp. nov. a – median lobe in lateral view; b – parameres. Scale bar = 0.5 mm.

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.

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