Rhyparus guadalcanalensis 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 guadalcanalensis

description: Rhyparus guadalcanalensis Minkina, Skelley, Jákl, Král & Li, new species
(Figs 2A–C, 4A–B)
Type locality. Solomon Islands, Guadalcanal Island, Karukiki env., 20–25km SSE of Honiara.
Type material (107 exx.). Holotype (male): Solomon Islands —south / Pacific, Guadalcanal I. / 750–900m., Karukiki env., 20– / 25km SSE of Honiara / 1–18.xii.2016 / leg. S. Jakl (ISEA). Paratypes: 3 exx.: same data as holotype (ISEA); 16exx.: South Pacific, Solomon Is. / Guadalcanal I., 50–200m. / Lunga river env., ca 10–15km S / of Barana vill., Honiara reg. / 21.xi.–17.xii.2017, leg. St. Jakl (11 exx. SJCP; 5 exx. ISEA); 16 exx.: South Pacific, Solomon Is. / Guadalcanal I., 500–650m. / Koso vill. Env., ca 15–18km SSE / of Honiara, 1.–18.xii.2016 / leg. St. Jakl (11 exx. SJCP; 5 exx. ISEA); 40 exx.: Solomon Islands / South Pacific, Malaita Island / south coast Hahorarumu Uru / Tribal Area (conservation area) / 100–250m., 7.–13.xii.2017 / leg. S. Jakl (28 exx. SJCP; 12 exx. ISEA); 1ex.: Solomon Isands / Guadalcanal Island, 50–100m. / Lunga river env., 5–15km S of / Barana vill., Honiara reg. / 22.xi.–18.xii.2018, leg. St. Jakl (SJCP); 1 ex.: Solomon Islands: / Guadalcanal Is, Koso vill. Env., / alt. 500-650m, 2016.vii. 1–18 / St. Jakl leg. (EUMJ); 1 ex.: Solomon Is. / Kolombangara / Pepele, 30 m / 6.ii.1964 // P. Shanahan / collector / Bishop (BPBM); 1 ex.: Solomon Is. / Santa Ysabel [Isabel] / Molao, 29.vi.1960 // C. W. O’Brien / collector (BPBM); 2 exx.: Solomon Is., Santa Ysabel [Isabel] / Sakapisu, 900 m / 19.vi.1960 // light trap // C.W.O’Brien / collector (BPBM); 9 exx.: Solomon Is. / Fauro I., Toumoa / Village, 30m. / 3.iv.1964 // P. Shanahan / collector / Bishop // light trap / Bishop (7 BPBM, 2 FSCA); 2 exx.: Solomon Is. / Fauro I., Toumoa / Village, 30 m. / 7.iv.1964 // P. Shanahan / collector / Bishop // light trap / Bishop (FSCA); 4 exx.: Solomon Is. / Fauro I., Toumoa / Village, 30 m. / 12.iv.1964 // P. Shanahan / collector / Bishop // light trap / Bishop (BPBM); 3 exx.: [PNG] Solomon Is. / Bougainville / Kukagai Vill. / 150m, x.1960 / W.W. Brandt / collector / Bishop (BPBM); 1ex.: [PNG] Solomon Is. / Bougainville / Kukagai Vill. / 150 m, xi.1960 / W.W. Brandt / collector / Bishop (BPBM); 3 exx.: [PNG] Solomon Is. / Bougainville / Kukagai Vill. / 150m, xii.1960 / W.W. Brandt / collector / Bishop (1 ex. BPBM; 2 exx. FSCA); 5 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).
Description of the holotype (male). Dorsum (Fig. 2A). Body length 4.7 mm; maximum width 1.55 mm. Body small-sized for the genus, quite distinctly elongate, not distinctly convex, flattened medially; surface matt; apparently glabrous, except head and all longitudinal costae and intercostae on pronotum and elytra with rows of very small, yellowish macrosetae. Dark brownish; antennae, tarsomeres and mouth parts pale brownish.
Head (Fig. 4A) transversely sub-hexagonal; matt, tops of ridges moderately shiny; clypeus trapezoidal in outline, anteriorly truncate, on each side upturned as obtuse tooth, laterally sinuous; genae distinctly more excavate than eyes; clypeal disc distinctly convex, ringed by a deep groove; convexity with a pair of distinct, short ridges that converge anteriorly, nearly entire surface with distinct, fine punctures bearing small setae. 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 matt, tops of costae distinctly shiny; with eight distinct costae and seven intercostae, lateral margin with two rounded lobes. Anterior lobe less prominent laterally and distinctly narrower than median lobe which is the widest part of the pronotum. Costae of middle, third and fourth pair entire from posterior to anterior margins; median pair 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 setae. All intercostae anteriorly without additional short costae. Median intercostae anteriorly with few punctures concentrated at middle; all intercostae lacking distinct punctures posteriorly, but with few irregularly spaced setae from minute punctures.
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 sides with very small punctures bearing very small setae. Intercostae 1–4 with two distinct rows of large punctures, medially surface smooth with one or two rows of small setae from minute 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 very weakly divided; medio-internal bulb transversely rounded, internally stretched.
Macropterous.
Pygidium with dense, irregularly spaced punctation, with distinct longitudinal carina medially and deep excision on each side.
Venter (Fig. 2B) weakly shiny. Metaventral plate flattened in the middle; with distinct, narrow, shallow, median longitudinal furrow; punctation plate dense, shallow, regularly spaced, slightly irregular in size; all punctures bearing short setae. Abdominal ventrites weakly shiny, with dense punctation bearing long and thin setae; with an additional coarsely punctured furrow on anterior margin; last abdominal ventrite medially flattened, lacking median carina (there are just two depressed areas on both sides of a median line that appears like a low carina). Meso- and metafemora without tubercles on posterior border; all femora shiny, with regular, very distinct, moderately large, very dense punctation; all punctures bearing thin macrosetae. Meso- and metatibiae (Fig. 4B) with inner margin regularly rounded entire length to a large inner apical tooth.
Variation. Length 4.4–6.3 mm, width 1.45–2.10 mm. Punctation of pronotum can be slightly more or less coarse; rows of minute punctures on elytra can be more or less dense. Sexual dimorphism evident in the shape of the male meso- and metatibiae, which are weakly sinuate on inner edge and are distinctly inwardly hooked at apex. Additionally, the last abdominal ventrite of males is somewhat elevated and flattened medially, lacking median carina (there are two depressed areas on both sides of a median line that appears like a low carina). In females, the last abdominal ventrite is not elevated, weakly flattened, with no depressed areas like in males.
Etymology. Toponymic; an adjective derived from the name of Guadalcanal Island, where the holotype was collected.
Differential diagnosis. Rhyparus guadalcanalensis, new species is a small to moderately sized member of the genus with punctation of pronotum visible only in anterior third of the median intercostae, lateral lobes of pronotum distinctly developed, and weakly developed caudal bulbs. It can be confused only with R. helophoroides Fairmaire, 1893, with which it is sometimes sympatric. Males of both species are very easily distinguishable from each other. They have differently shaped metatibiae (compare Fig. 4B and Fig. 4C; also see fig. 4A in Anichtchenko et al. 2021 or fig. 31 in Minkina & Jákl 2024), and R. helophoroides males have the last abdominal ventrite with a strong, median carina nearly complete from base to apex. Additionally, males and females of R. helophoroides are somewhat smaller, in most cases have the pronotum with larger punctures on entire surface of median intercostae (especially in basal part) and at most have mintue setae on elytral intercostae, rarely visible.
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 564-566, DOI: 10.11646/zootaxa.5570.3.7, http://zenodo.org/record/14745461