Resachus gillianae Matsumoto, 2020

Matsumoto, Keita, 2020, Description of new species of Resachus Delève, 1968 (Coleoptera: Limnichidae), Zootaxa 4852 (5), pp. 578-581 : 578-580

Resachus gillianae Matsumoto sp. nov. [ Figures 1-6 ]

Type locality. Malawi, Kaphula .

Type materials. Holotype male, deposited at BMNH: “ MALAWI south KAPHULA env. December 2003 at light; J.Novák lgt. BMNH{E}2016-44 // NHMUK011225326”. Additional label on red paper added “ Resachus gillianae Matsumoto sp. nov. 2020 HOLOTYPE ♂ ” . Paratypes (2 males, 2 females. BMNH): same locality data as holotype with additional label: “NHMUK011225327”, “NHMUK011225328, “NHMUK011225329” and “NHMUK011225330”. All paratype specimens have been labelled with a red paratype label: “ Resachus gillianae sp. nov. K. Matsumoto 2020 PARATYPE [♂ or ♀]” .

Description of holotype, male. Colour: Dorsal side brown; venter brown to reddish brown, tibia brown, tarsal claws light brown. Dorsal and ventral surface densely covered with long setae. Body: Elongate, oval, dorsum convex, EL: 2.4 mm, EW: 1.8 mm, PL: 0.7 mm, PW: 1.6 mm.

Dorsum. Head: Partially retracted into pronotum; overall surface smooth, relatively large punctation densely spread across surface. Antennae: 11 segmented, filiform, fully pubescent, antennomeres long and slender, 1st AS widest, 2nd AS narrow and long, 3rd AS smallest, 4th to 8th AS long and thin, 9th AS skewed oval, 10th and 11th AS wide and slightly concave posteriorly. Pronotum: Transverse, widest at posterior, narrowest at anterior, narrower than elytra; anterior margin convex, posterior margin tri-sinuate, lateral margin convex; surface covered with dense punctation, surface between punctures smooth and shiny. Scutellum: Subtriangular, large, lateral sides nearly straight. Elytra: Longer than wide; anterior margin very convex, sinuate; anterior lateral angle nearly right angled, rounded; lateral margins gently curved from anterior end to anterior 2/3, increasing in curvature towards the apex; surface with mixtures of small fine and dense punctuation; medium sized punctures forming irregular striae near the elytral suture, elytral striae more clearly visible towards lateral margin; surface between punctures smooth and shiny.

Venter. Prosternum: Concave on anterior margin, outer lateral margin concave; prosternal process longer than wide, lateral margin curved, posterior margin rounded. Mesoventrite: Wider than long, narrows towards posterior; anterior margin concave where prosternal process fits, discrimen not clearly visible; lateral sub-parallel and gently curved, posterior sinuate, anterior tri-sinuate. Metaventrite: Long and wide, flat on the middle; discrimen thin visible across each end. Abdomen: Five clearly visible ventrites. Intercoxal process sinuate with pointed apex. Posterior margin of 1st and 2nd ventrites convex, 3rd to 4th ventrites slightly concave, 5th ventrite curved. Surface covered with long, light yellow, recumbent setae.

Legs. Tibiae: Outer lateral margin almost straight, inner lateral margin straight. Tarsi: Simple, segments increase in length towards the apex, fifth tarsal segment as long as first to fourth tarsal segment combined. Tarsal claws: Long, narrow, symmetrical.

Genitalia. Aedeagus: Elongate, strongly sclerotized. Base: Asymmetrical, widest around basal 0.2 in ventral view and 0.5 in lateral view. Median lobe: Approximately 1/2 the length of genitalia; longer than parameres; consistent width on the basal half, widest at middle and narrows towards the apex in lateral view; longer than parameres in lateral view; narrows gradually towards the apex, apex nearly flat and slightly curved in ventral view. There are two convex emarginations, one near the apex of the median lobe and another smaller one lower down on the median lobe ( Figure 6 ). Parameres: Slightly wider than median lobe in ventral view; inner margin concave and outer margin a smooth convex curve in ventral view; apical emargination close to V-shaped; ventral margin sinuates and dorsal margin concave in lateral view; apex rounded in both ventral and lateral views.

Female: No morphological difference from male except for the 5th abdominal ventrite longer than male. Ovipositor long, gonocoxites strongly tapering to a point.

Distribution: Resachus gillianae Matsumoto sp. nov. is known only from the type locality and it is the new country record from this genus for Malawi.

Etymology: This species is named after Gillian Crossan, long-term volunteer at BMNH who has contributed so much to the improvement of the collection. She was involved with recuration of Buprestidae collection, accessioning Milan Krajčík collection ( Scarabaeidae : Cetoniinae ) and Rainer Schimmel collection ( Elateridae ), etc.

Differential diagnosis: Resachus gillianae Matsumoto sp. nov. is closely related to Resachus schuhi Hernando & Ribera, 2006 from Madagascar, but can be easily distinguished by the following characters of Resachus gillianae . 1, Presence of two convex emarginations on the median lobe near the apex; 2, dorsal margin of parameres concave in lateral view; 3, parameres narrowing towards the apex; 4, apical emargination of parameres close to V-shaped rather than U-shaped as in Resachus schuhi .

Figures

FIGURES 6. Resachus gillianae Matsumoto sp. nov., holotype, male, genitalia lateral close-up.

FIGURES 1–5. Resachus gillianae Matsumoto sp. nov., holotype, male. 1, dorsal habitus; 2, ventral habitus; 3, abdomen; 4, genitalia ventral; 5, genitalia lateral. Not to scale.