Rhyparus rugatus Arrow, 1935

Rhyparus rugatus Arrow, 1935 View in CoL

Figures 34–39 View FIGURES 34–39

Rhyparus rugatus Arrow, 1935: 159–160 View in CoL . Type locality: “New Hebrides” [ Vanuatu], Malekula Island , Ounua.

Diagnosis. A member of the genus Rhyparus , distinguished by the larger body size, length 6.0– 7.5 mm ( Figs. 34–38 View FIGURES 34–39 ). Pronotum with triangularly prominent lateral anterior and intermediate lobes; costa prominent, carinate; median intercostal punctation coarse. Elytra with intercostae strongly rugose; first elytral intercosta with three rows of punctures (rarely two, often obscured by rugosity); small trichome on prominent caudal bulb which has two sharply defined external lobes ( Figs. 34–35, 37 View FIGURES 34–39 ). Mesotarsus and metatarsus with ventral surface densely pilose, hiding surface. Male genitalia with basal piece about four times longer than parameres ( Fig. 38 View FIGURES 34–39 ). Known only from Vanuatu.

Redescription. Body large, length 6.0– 7.5 mm, width 2.3–2.7 mm; black, dulled. Head with clypeal anterior margin on each side obtusely angled; gena distinct; centroclypeal disc with indistinct punctures, bearing two short, weak longitudinal ridge at middle; frontal costa distinct. Pronotal and elytral costae distinctly raised, sharply defined; in lateral view, slightly undulating. Pronotum with paramedian costae convergent and less distinct at mid-length; median intercostae with large irregular punctures occupying most of surface; more lateral intercostal lacking distinct punctures on posterior half; lateral margin bearing distinct triangular anterior and medial lobes. Elytra with intercostae somewhat flattened, strongly rugose; first intercosta usually with three (rarely two) rows of punctures; second, third and fourth intercostae with two rows of punctures; third (humeral) intercostal lacking costal remnant at base); discomedial costa weakly swollen at caudal end, which has a small patch of short setae; caudal bulb with two distinct, conical prominent lobes, one at posterior end of submarginal costa and one posterior of discomedian costa; caudal trichome small, trichome on anterior margin of caudal bulb notably smaller than bulb; surface posterior to caudal bulb with single row of very large punctures, separate by distinct longitudinal carinae. Venter. Metaventrite smooth, surface with coarse punctures; median longitudinal groove narrow, with weak longitudinal ridges on each side. Abdomen with ventrites coarsely punctate, each with distinct triangular fovea on each side. Abdominal ventrites 2–3 smooth or weakly crenate along anterior groove; ventrite 4 moderately crenate; ventrite 5 with anterior groove very deep, slightly widest medially, strongly crenate deep in groove, surface of male with short weak median carina anteriorly. Pygidium of male and female, with strong median carina and deep triangular fossae on each side. Legs. Profemur with ventral surfaced coarsely deeply punctate, mesofemur and metafemur each less coarsely punctate; mesofemur with two teeth on posterior margin. Mesotibia of male with inner margin distinctly sinuate, with distinct inner apical tooth; tooth lacking in female. Metatibia of male with small inner apical tooth. Mesotarsus and metatarsus with ventral surface densely pilose, hiding surface. Genitalia of male with long tubular basal section, paramere length less than ¼ length of basal section.

Variation. The series available shows a lot of variation in the strength of the elytral surface rugosity. A few have the surface nearly smooth, most have the rugosity obscuring the coarse punctures. Some are so rugose that the coarse punctures are obscured. There is also variation in the number of puncture rows in the first costal interval, the majority having three rows. The lectotype shows an intermediate state between smooth and strongly rugose, and two or three rows of punctures. Other variation is notable in the shape of the lobes on the caudal bulb. Most are somewhat conical, some are more flattened, others (like on the lectotype) they are nearly cylindrical.

Distribution. Vanuatu (Malekula, Pentecost, Tanna islands).

Material examined. The lectotype male ( NHML, here designated): “ New Hebrides: [with orange underline] / Malekula, / Ounua. / Mar. & Apl. 1929. / Miss L. E. Cheesman. / B.M. 1929—343. // ♂ // [handwritten, cursive] Rhyparus / rugatus / Type Arrow // [handwritten] 238 // [QR Code label] NHMUK 013906235 // [circular label with blue outline] SYN- / TYPE // [red label] LECTOTYPE ♂ / Rhyparus rugatus / Arrow, des. Skelley / & Minkina 2024 ” ( Fig. 39 View FIGURES 34–39 ). Paralectotypes, two female specimens ( NHML), both similarly labeled: “ New Hebrides: [with orange underline] / Malekula, / Ounua. / Feb. 1929. / Miss L. E. Cheesman. / B.M. 1929—234. // [handwritten] 232 // [circular label with blue outline] SYN- / TYPE // [yellow label] PARALECTOTYPE / Rhyparus rugatus / Arrow, des. Skelley / & Minkina 2024 ”. They have QR Code labels “NHMUK 016194810” and “NHMUK 016194811”.

Other materials (61 total). Vanuatu [New Hebrides]: Tanna Island , Lenakel, 0–150 m, I.1977, N.L.H. Krauss, Coll., Bishop Museum, Acc. #1977.81 (1 BPBM) ; Tanna Island , Lenakel, 0–200 m, III.1980, N.L.H. Krauss, Coll., Bishop Museum, Acc. #1980.128 (6 BPBM, 2 FSCA) ; Pentecost Island , 4–5.IV.1964, R. Straatman, light trap (37 BPBM, 4 CMNC, 7 FSCA, 4 ISEA) .

Comments. Arrow (1935) stated studying three specimens when he described R. rugatus , but did not designate a holotype. To stabilize nomenclature to a single specimen, we here designate the illustrated syntype ( Figs. 34–38 View FIGURES 34–39 ) as the lectotype of R. rugatus . There are two paralectotypes from the same collection.

Rhyparus rugatus belongs to a complex of species that needs revision. To help with this future work, we redescribe, illustrate, and designate a lectotype for R. rugatus . Stebnicka (1998) stated R. rugatus might by a synonym of R. breviceps from New Guinea and the Solomon Islands ( Minkina et al. 2025). However, she had a limited number of specimens available for study. With the available series of specimens, we see that some individuals have variations where certain characters are similar to R. breviceps . However, none has the combination of all characters at the same time as seen in normal R. breviceps . These consistent differences and their isolated distributions warrant retaining them as distinct species.