Rhyparus malaitaensis Minkina, Skelley, JAkl, KrAl & Li 2025, new species
Creators: name: Minkina, Łukasz
name: Skelley, Paul
name: Jákl, Stanislav
name: Král, David
name: Li, Xiao-Feng
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Scarabaeidae
Rhyparus
Rhyparus malaitaensis

description: Rhyparus malaitaensis Minkina, Skelley, Jákl, Král & Li, new species
(Figs. 3A–C, 4D–E)
Type locality. Solomon Islands, Malaita Island, south coast Hahorarumu Uru, Tribal Area
Type material (29 exx.). Holotype (female): Solomon Islands / South Pacific, Malaita Island / south coast Hahorarumu Uru / Tribal Area (conservation area) / 100–250m., 7.–13.xii.2017 / leg. S. Jakl (ISEA). Paratypes: 11 exx.: same data as holotype (8 exx. SJCP; 3 exx. ISEA); 3 exx.: South Pacific, Solomon Is. / Malaita I., south coast / Hahorarumu Uru Tribal Area / (conservation area) 100–250 m. / 7.–13.xii.2017 leg. S. Jakl (2 exx. SJCP; 1 ex. ISEA); 1ex.: Solomon Islands / South Pacific, Guadalcanal I. / 750–900 m., Karukiki env. / 20–25km SSE of Honiara / 1–18.xii.2016 / leg. St. Jakl (ISEA); 5 exx.: Solomon Islands / Malaita Is. Cca 6km NW / Waisisi vill. env. 340 m. / 09˚20.1’S 16˚07.6’E / J. HorÁk leg. 5.–11.xii.2017 (3 exx. JHCP; 1 ex. ISEA, 1 ex. NMPC); 1ex. (male): Solomon Is. / Vella Lavella / Ulo Crater, 10m / XII.1963 // at kerosene / light (BPBM); 1 ex. (female): Solomon Is. / Choiseul I. / Kitipi R., 80m / 14.III.1964 // P. Shanahan / collector / Bishop // light trap // Bishop (BPBM); 1 ex. (male): Solomon Is. / San Cristoval [Cristobal] / Wugiroba / 7.VIII.1960 // light trap // C. W. O’Brien / Collector (BPBM) 1ex. (female): [PNG] Solomon Is. / Bougainville / Kukugai Vill. / 150 m, XII.1960 // W.W. Brandt / Collector / Bishop (FSCA); 1 ex. (male): [PNG] Bougainville / Trapanas, 200m / 27.2.1968 // Tawi / Collector / Bishop (BPBM); 2 exx.: Solomon Islands, Guadalcanal / Is. Marau area, Puatanarau vill. env., / 9˚45’44’’S 160˚46’44’’E, 09.v.2023 / 20–40 m, mangroves & Pandanus / forest, leg. D. Telnov / BMNH{E}2023-95 (NHMUK); 1ex.: Solomon Islands, Guadalcanal / Is., Honiara S env., Barana vill. S / env., 1 km around 9˚29’5’’S / 159˚58’40’’E, 20 –23.iv.2023, 220– / 350m, disturbed lowland rainforest / on limestone, leg. D. Telnov / BMNH{E}2023-95 (NHMUK).
Description of the holotype (female). Dorsum (Fig. 3A). Body length 7.8 mm; maximum width 2.45 mm. Body large-sized for the genus, distinctly elongate, not distinctly convex, flattened medially; matt; apparently almost glabrous, except head and longitudinal costae on pronotum and eltyra partly clothed with very short and thin, yellowish macrosetae. Dark brownish; antennae, tarsomeres and mouth parts pale brownish.
Head (Fig. 4D) transversely sub-hexagonal; surface very weakly shiny, tops of ridges moderately shiny; clypeus trapezoidal in outline, anteriorly truncate, on each side upturned as obtuse, weak tooth, laterally sinuous; genae distinctly more excavate than eyes; clypeal disc distinctly convex, ringed by a deep groove; convexity with a pair of quite distinct, very short, ridges that converge anteriorly, nearly whole surface with distinct, fine punctures bearing small macrosetae. Frons with four distinct, longitudinal ridges with similar structure as ridges on clypeal convexity. Head covered by regularly spaced, dense, moderately large punctures bearing short macrosetae.
Pronotum very weakly shiny, tops of costae distinctly shiny; with eight distinct costae and seven intercostae, lateral margin with two rounded lobes. Anterior lobe very weakly more prominent laterally and distinctly narrower than median lobe, anterior lobes are the widest part of pronotum. Costae of middle, third and fourth pair entire from posterior to anterior margins; median pair very gently convergent anteriorly, distinctly convergent in the middle of anterior third; second pair of costae distinctly interrupted in anterior half; all costae on each side with very small punctures bearing very small macrosetae. All intercostae anteriorly without additional short costae. Median intercostae with dense punctures, distinctly concentrated medially into a longitudinal line, all intercostae posteriorly with distinct, dense punctation.
Scutellum almost imperceptible.
Elytra matt, tops of costae and preapical glandular area distinctly shiny. Each elytron with six elevated, distinctly convex costae, and five flat intercostae. Costae on each side with very small punctures bearing very small setae. Intercostae 1–4 with two distinct rows of punctures, medially smooth; basally third intercostae with short costal remnant and additional median row of small sparse punctures extending to apical third of elytra; humeral region of fourth intercosta with dense, irregularly spaced additional punctures; fifth intercosta with one row of punctures. Preapical glandular area relatively small. External caudal bulb distinctly reduced, area between external caudal bulb and sides of elytra not divided; external and mediointernal caudal bulbs not divided; medio-internal caudal bulb shortened, transversely rounded, internally stretched.
Macropterous.
Pygidium (Fig. 4E) triangular with acute apex, distinctly bent inwards in lateral view (not perpendicular to body axis), with dense, irregularly spaced punctation, with weak longitudinal carina in the middle and deep excision on each side.
Venter (Fig. 3B) moderately shiny. Metaventral plate flattened in the middle; with distinct, narrow, quite deep longitudinal furrow on posterior half; punctation of plate dense, quite regularly spaced, slightly irregular in size; all punctures bearing short macrosetae. Abdominal ventrites weakly shiny, on sides with rows of punctures; anteriorly with an additional punctured furrow. Last abdominal ventrite shortened medially for reception of pygidium, with dense punctures, which are about one and half time larger than on penultimate ventrite; anterior half with dense, very deep punctures (pits) separated by narrow longitudinal ridges; posterior part in the middle with very deep groove, located very slightly below apex of pygidium. Meso- and metafemora with two very indistinct tubercles on posterior border; all femora shiny, with regular, very distinct, rather small, very dense punctation; all punctures bearing small macrosetae.
Variation. Length 6.2–8.6 mm, width 2.00– 2.65 mm. Punctation of pronotum can be more or less dense. Sexual dimorphism evident in the shape of meso- and metatibiae, which are weakly sinuate on inner edge and are distinctly inwardly hooked at apex; additionally last abdominal ventrite and pygidium in males are not modified.
Etymology. Toponymic; an adjective derived from the name of Malaita Island, where the holotype was collected.
Differential diagnosis. Rhyparus malaitaensis, new species belongs to the group of species with females having a modified pygidium and last abdominal ventrite. Due to this modification, females are always easily distinguishable from other Rhyparus species. Males of this group are not so easily distinguishable and for this reason we selected a female as the holotype. Members of this group can be distinguished from other Rhyparus by the relatively large body (for a representatives of the genus), with a body length in nearly all cases more than 6.0 mm, elongate body, relatively weakly developed, rounded lateral lobes of pronotum, and weakly developed caudal bulbs.
The pygidium of female R. malaitaensis, new species has the apex acute, shaped like a distinct triangle (not truncate). Of all species in the group with a modified female pygidium, only R. bacanensis Minkina, Anichtchenko, Vasiljeva & Skelley 2022 and R. argopuroensis Minkina & Jákl, 2024 have a similar pygidial apex (see figs 26–33 in Minkina et al. 2022 and figs 1–3, 22, 29 in Minkina & Jákl 2024), but they have different last abdominal ventrites. In R. malaitaensis, new species the pits in the anterior furrow are about 1.5–2.5 times longer than wider; in R. bacanensis the pits are about 3.5–5.0 times longer than wider; while R. argopuorensis, has much smaller pits, similar to large punctures. Rhyparus bacanensis have apical part of last abdominal ventrite located distinctly below the pygidial apex; R. malaitaensis, new species and R. argopuroensis have apical part of last abdominal ventrite located very slightly below the pygidial apex. Female pygidia of these three species are not easy to distinguish without having specimens of all species for comparison: proportions and prominence (especially median carina of pygidium) are slightly different. Another feature that distinguishes females of R. malaitaensis, new species and R. argopuroensis from R. bacanensis is the shape of metaventral plate: Rhyparus bacanensis have distinct concavities on each side of the median longitudinal furrow, which are lacking on R. malaitaensis, new species and R. argopuroensis.
Males of this group with modified female pygidia are difficult to distinguish. Males of R. malaitaensis, new species can be recognised by comparing the following combination of characters with those presented in Table 1 and Table 2 of Minkina et al. (2022): all costae shiny, intercostae of pronotum weakly shiny, intercostae of elytra matt; body distinctly elongate, lateral lobes of pronotum weakly developed, sinuation between them not so distinct, anterior lateral lobe of pronotum triangular, very slightly higher than posteriorly; posterior lateral lobe of pronotum widely, regularly rounded; punctation of median intercostae of pronotum dense, regularly spaced, distinctly concentrate in the middle into longitudinal line, punctures coarse here; elytral costae distinctly convex, relatively narrow; some additional fine punctures are observed on all intercostae; third intercostae with three distinct rows of moderately coarse punctures.
Additionally it can be identified from other members of the genus Rhyparus from the Solomon Islands using the key below.
description: Published as part of Minkina, Łukasz, Skelley, Paul, Jákl, Stanislav, Král, David & Li, Xiao-Feng, 2025, Review of the genus Rhyparus Westwood, 1845 (Coleoptera: Scarabaeidae: Aphodiinae) in the Solomon Islands with description of two new species, pp. 563-573 in Zootaxa 5570 (3) on pages 569-572, DOI: 10.11646/zootaxa.5570.3.7, http://zenodo.org/record/14745461