Platynectes lunga, 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 : 62-63

publication ID	https://doi.org/ 10.37520/aemnp.2023.002
publication LSID	lsid:zoobank.org:pub:B70AC6B5-C590-483E-ACF8-16FA5985C9A3
persistent identifier	https://treatment.plazi.org/id/86483714-FF8F-FFDC-FC03-FF02FB90FD91
treatment provided by	Felipe
scientific name	Platynectes lunga
status	sp. nov.

Treatment

Platynectes lunga sp. nov.

( Figs 2 View Figs 1–3 , 9 View Figs 8–11 )

Type locality. Solomon Islands, Guadalcanal, 3.5 km SE of Barana village Type material. HOLOTYPE: J ( NMPC), labelled: ‘ SOLOMON ISLANDS, GUADALCANAL / ca. 3.5 km SE of BARANA vill. / (drying up stream in shaded gorge) / 09°29.8′S, 159°59.5′E; 190 m / Jiří Hájek leg., 24.xi.- 14.xii.2013 [p] // HOLOTYPE J / PLATYNECTES / lunga sp. nov. / J. Hájek et al. det. 2021 [p, red label]’. PARATYPES: 25 JJ 16 ♀♀, same label data as holotype; two specimens with additional label: ‘DNA / M. Balke / 6322 [6323 respectively] [p, white label]’ ( BPBM, JSCL, NMPC, ZSMG); 1 J 2 ♀♀, labelled: ‘ SOLOMON ISLANDS, GUADALCANAL / Mt. Austine - BARANA vill. env. / (secondary forest, gardens, stream) / 09°28.0′S, 159°58.4′E; 280 m / Jiří Hájek leg., 23.xi.-8.xii.2013 [p]’; 4 JJ 1♀, labelled: ‘ SOLOMON ISLANDS, GUADALCANAL / ca. 4.5 km S of BARANA vill., forest / nr. „Japanese camp“ & Moka river / 09°30.3′S, 159°58.9′E; 275 m / Jiří Hájek leg., 5.-6.xii.2013 [p]’ ( NMPC); 8 JJ 5 ♀♀, labelled:‘ SOLOMON ISLANDS, GUADALCANAL / LUNGA river env., Honiara reg. / 5-15km S of Barana vill./ 50-100 m, 22.xi.-18.xii.2016 / St. Jákl leg.’ ( NMPC); 31 Jm 47 ♀♀, labelled: ‘ SOLOMON ISLANDS, GUADALCANAL / Koso vill. env./ 15-18km SSE of Honiara / 500-650 m, 1.-18.xii.2016 / St. Jákl leg.’ ( NMPC, SJCP); 26 JJ 14 ♀♀, labelled: ‘ Solomon Islands / GUADALCANAL I., Honiara reg. / Barana vill.env. 100-300 / XI-XII.2018 / St. Jakl leg. / Coll. Hendrich’ ( LHCM, NMPC, ZSMG); 3 JJ 1 ♀, labelled: ‘Solomon Is. GUDALCANAL [sic!] I. / 80-250m, Lunga River env., 5-15 km / S of Barana vill., Honiara Reg. / 20.XI/ 15.XII.2013 [sic!] / St. Jakl leg./ Coll. Hendrich’ ( LHCM); 2 JJ, labelled: ‘South Pacific, Solomon Isl., / Guadalcanal 750-900 m / Karukiki env. 20-25 km SSE / Of Honiara, 1.-18.XII.2016 / St. Jakl leg./ Coll. Hendrich’ ( LHCM); 5JJ 4♀♀, labelled: ‘South Pacific, Solomon Isl. / Guadalcanal 50-200m / LUNGA river env. 5-15 km S of / Barana vill., Honiara reg. / 22.XI.-18.XII.2016 / St. Jakl leg./ Coll. Hendrich’ ( LHCM). 9 JJ 2♀♀, labelled: ʻSalomonen: C-Guadalcanal, / 0.5 km N Mbaole, 2799 feet / S 09°37.69 E 160°06.69E / 2007 K. Mailautoka leg. [p]’; two specimens with additional label:‘DNA / M. Balke / 2909 [3336 respectively] [p, green label]’ ( ZSMG);5JJ 3♀♀, labelled:ʻSOLOMON IS.: [red underlined] / Guadalcanal I. / Tapenanje. c. 1,100 ft. / 21-23. xii.1953. / J.D.Bradley [p] // RENNEL I. / Expedition. / B.M.1954-222 [p]’ ( BMNH); 1 J 1♀, same label data, but with additional label: ʻfrom / small stream [hw]’ ( BMNH); 4JJ 2♀♀, same label data, but first locality label handwritten ( BMNH); 4 JJ 6 ♀♀, labelled: ʻSOLOMON IS.: [orange underlined] / Guadalcanal Is. / Suta / 27.vi.1956 [p] // E.S.Brown / B.M.1957-201 [p]’ ( BMNH); 3 JJ 3 ♀♀, labelled: ʻSOLOMON IS. / Guadalcanal, Suta / VI-27-1956 // J.L. Gressitt collector [p]’ ( BPBM); 1 J 2 ♀♀, labelled: ʻSOLOMON IS. / Guadalcanal / Betikama R. / VIII.1960 // W.W. Brandt collector / Bishop’ [p.] ( BPBM); 1 J 3 ♀♀, labelled: ʻSOLOMON ISLANDS [orange underlined] / Guadalcanal, / Nuhu.26.x.65 / Roy. Soc.Exped./ B.M.1966-1. [p] // slow flowing pool. [p]’ ( BMNH); 2 JJ, labelled: ʻ [on side:] 5316 [hw] / SOLOMON IS. / Guadalcanal [p] / Sorrohio R. / 26.vi. [hw] 195 [p] 6 [hw] / E.S.Brown [p] // Pres. by / Com.Inst.Ent./ B.M.1958-79 [p]’ ( BMNH).All paratypes with the respective red printed label.

Additional material studied. SOLOMON ISLANDS: SAVO: 7.x.1956., E.S.Brown, 11 specimens ( BMNH, NMPC, ZSMG).

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

Colouration ( Fig. 2 View Figs 1–3 ). 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 more or less distinct yellowish pattern consisting of postmedial spot in two thirds of elytral length, and three subapical spots; postmedial spot transverse, in centre narrowed; subapical spots consisting of two narrow longitudinal spots and oblique spot posterolaterally from them. Legs brown, basal part of metafemora brown-blackish. Prosternum and metacoxal processes brown.

Head ca. 0.62× width of pronotum, transversely elliptical. Meshes of reticulation mostly complete (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 perceptible laterally close to sides. Centre of pronotal disc with small fossa.

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 but slightly less impressed, consisting of heterogeneous polygonal meshes; meshes mostly complete. Traces of microreticulation perceptible in apical half and laterally on elytra.

Ventral surface. Medial part of metaventrite with rather dense fine punctation. Ratio WC/WS = 4.3. Metacoxal lines incomplete anteriorly, almost parallel-sided. Metacoxal plates reticulated with polygonal meshes, punctation consisting of sparse fine punctures; plates with short longitudinal strioles, and long, weakly impressed transverse striae.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. 9a View Figs 8–11 ) in lateral aspect only very slightly broadened to rounded apex; apex distinctly setose apico-ventrally. Parameres ( Fig. 9b View Figs 8–11 ) narrowly triangular, slender, incised basally; dorsal surface densely setated; apical lobe long.

Female. Identical to male in habitus. Reticulation of dorsal surface more impressed, traces of microreticulation perceptible over major part of elytra; pro- and mesotarsomeres 1–3 not dilated and without adhesive setae; abdominal ventrite VI with sublateral grooves less developed.

Measurements. TL: 5.6–6.6 mm (mean value: 6.25 ± 0.20 mm); holotype: 6.15 mm. TL-h: 5.0–6.0 mm (mean value: 5.55 ± 0.15 mm); holotype: 5.5 mm. MW: 3.2–3.9 mm (mean value: 3.60 ± 0.10 mm); holotype: 3.55 mm.

Variability. The specimens of the type series vary only in shape and size of yellow markings on dorsal surface, especially in the presence of an additional spot medially on frons, and the presence of subbasal spots on elytra; postmedian orange spot on elytra can be split into two spots.

Differential diagnosis. The new species can be recognized from all other Platynectes from the Solomon Islands by combination of reduced yellow dorsal surface pattern ( Fig. 2 View Figs 1–3 ), closed meshes of dorsal surface reticulation, and the shape of male genitalia with median lobe slender in lateral view ( Fig. 9 View Figs 8–11 ). Based on the shape of the median lobe, P. lunga sp. nov. seems to be the most similar to P. malaita sp. nov., from which it differs in slightly larger body length (mean value = 6.25 ± 0.20 mm in P. lunga sp. nov., but only 5.85 ± 0.15 mm in P. malaita sp. nov.), less impressed dorsal surface reticulation) and much more reduced yellow colouration on elytra (see also under the latter species).

Etymology. The new species is named after its area of occurrence – Lunga river; majority of specimens was collected in its lower basin. The specific epithet is a noun in the nominative singular, standing in apposition.

Collecting circumstances. At the type locality, the species was collected in shaded pools of temporary forest stream ( Fig. 22 View Figs 22–24 ). At night, Platynectes specimens were observed to leave pools and crawl in nearby hygropetric habitats, e.g. wet bank of pools, or a small spring ( Fig. 23 View Figs 22–24 ). At “Japanese camp”, it was found in a forest spring ( Fig. 24 View Figs 22–24 ); at the other places, the specimens were collected in pools with muddy bottom made by forest stream, see also under P. barana sp. nov.

Distribution. The new species is known from low and medium altitude area (ca. 190–650 m) in north-central Guadalcanal, and from Savo Island situated north-westwards from Guadalcanal ( Fig. 25A View Fig ).