Derelomus fasciatus Hartmann, 1904

Derelomus fasciatus Hartmann, 1904

Fig. 19 View Fig

Derelomus fasciatus Hartmann, 1904: 404 .

Derelomus fasciatus – Haran et al. 2022a (phylogenetic relationships); 2023a (life history).

Diagnosis

This species can be distinguished by its narrow body, the pronotum being isodiametric and the elytra elongate (W: L ratio: 0.6), its long and narrow rostrum, longer than the pronotum in lateral view, and simple claws. In most specimens, the dark pattern on the elytra forms a spot at the base of each elytron and a bisinuate transverse strip near the middle of the length. GenBank accession numbers for the corresponding DNA barcodes: OK188823 View Materials / OK283507 View Materials / ON553434 View Materials –35.

Material examined

Lectotype (here designated)

TANZANIA • ♀; “ Usambara [Tanzania]; Kraatz.[Ernst Gustav Kraatz, german entomologist]” “1; 04” “ Derelomus ; fasciatus Htm ” “SYNTYPUS” “Samml K. F. Hartmann; Ankauf 1941.1” “Staatl. Museum für; Tierkunde Dresden” “LECTOTYPE ♀; Derelomus ; fasciatus ; Hartmann, 1904; Haran des. 2025”; MTD.

Paralectotypes

TANZANIA • 1 ♀; Usambara mountains ; 4°44′56″ N, 38°27′00″ E; E.G. Kraatz coll.; MTD GoogleMaps • 2 ♀♀; Usambara mountains ; 4°44′56″ N, 38°27′00″ E; E.G. Kraatz coll.; “Ankauf, 1900, J. Faust coll.”; MTD GoogleMaps .

Other material

REPUBLIC OF SOUTH AFRICA – Western Cape Province • 2 ♂♂, 3 specs (preserved in ethanol); Gansbaai, Grootbos Private Nature Reserve ; 34°32′24″ S, 19°29′25″ E; 10 Aug. 2018; J. Haran coll.; beating flowers of Searsia glauca (Thunb.)Moffett ( Anacardiaceae ); JHAR01252 ; CBGP GoogleMaps • 2 ♂, 1 spec. (preserved in ethanol); Malgas; 34°18′00″ S, 20°34′48″ E; 26 Aug. 2018; J. Haran coll.; beating flowers of Searsia sp. ; JHAR01476 ; CBGP. GoogleMaps

TANZANIA • 1 ♀; same collection data as for lectotype; MTD • 3 ♂♂; Ukerewe Island; 2°02′35″ S, 33°00′18″ E; P.A. Conrade coll.; NHMUK. GoogleMaps

Redescription ( ♂)

MEASUREMENTS. Body length 2.0– 2.2 mm.

COLOR. Body integument pale brown; pattern on dorsum forming transverse and curved dark band near middle of length of elytra reaching sides laterally and dark spot at base of interstriae 4–5 of each elytron; dorsum glabrous.

HEAD. Rostrum longer than pronotum in lateral view (1.3 ×), almost straight in lateral view; in dorsal view about 5.5 × as long as wide, integument densely and finely punctate, forming 5 superficial longitudinal carinae from eyes to antennal insertion, median carina similar to others, split in two before antennal insertion; covered with scattered minute recumbent and non-contiguous whitish setae oriented transversally; antennae inserted near apical 1/5 of length in lateral view; head capsule coarsely punctate in dorsal view; forehead glabrous; eyes convex, strongly exceeding lateral curve of head capsule in dorsal view; antennal funicle with segment 1 as long as 2+3, 1.5× as long as wide, 3–4 isodiametric, 5–7 transverse.

PRONOTUM. Moderately transverse (W:L ratio: 1.15), widest near apical ⅓ of length, slightly narrower there than elytra at humeral angles (0.8 ×); sides convex, widening regularly apicad in basal ⅔ and converging abruptly in apical ⅓, lateral carina smooth, lacking constriction or tooth, apical constriction shallow narrower than width of scape at apex; integument punctate, space between punctures dull, micropunctate and reticulate, narrower or wider than diameter of a puncture.

ELYTRA. Elongate (W: L ratio: 0.45); sides subparallel in basal ½, widest near middle of length; humeri raised; apex rounded, not contiguous; striae with punctures 2–3 × narrower than width of interstriae; interstriae slightly convex, 9 raised into carina; scutellar shield rounded, with short whitish setae not concealing integument.

ABDOMEN. Underside covered with minute recumbent whitish setae, not contiguous. Stridulatory plate with series of 4–5 granules, forming lines converging apicad, as long as 0.75× the length of median area; apex of median area rounded ( Fig. 19E View Fig ).

LEGS. Profemora thickened near middle of length; protibiae with external margin straight, meso- and metatibiae slightly curved outward in apical half, internal margin of protibiae almost straight, curved inward in apical 1/5 only; claws simple.

TERMINALIA. Body of penis elongate (W: L ratio: 0.20), about 2 × as long as apodemes, widest near base in dorsal view; sides straight, converging moderately and regularly apicad, apex forming short and rounded spatula; in lateral view curvature stronger in basal ½ of length, width narrowing apicad from basal apical ¼ of length, apex curved upward ( Fig. 19D View Fig ).

Sexual dimorphism

The rostrum of females is distinctly longer (1.6 × as long as pronotum in lateral view) and more downcurved than in males. The antennae are inserted near the apical ⅓ of the length in females (near 1/ 5 in males; Fig. 19B–C View Fig ).

Life history

This species was found on inflorescences and infructescences of Searsia glauca and an unidentified Searsia ( Anacardiaceae ) in the Western Cape Province of the Republic of South Africa. Searsia in anthesis tends to attract a lot of insects, including weevils, not always associated with this bush at larval stages. However, several observations suggest that this species is restricted to Searsia : it was collected during daytime and at night on this plant only, at several sites and never recorded on flowers of the surrounding vegetation despite intensive search. Also, the specimens collected in Gansbaai consisted of ill-sclerotized and thus recently emerged individuals likely performing a maturation feeding on their host.

Distribution

South coast of the Western Cape Province of the Republic of South Africa, and Tanzania.

Remarks

In the Faust-Hartmann collection housed at MTD, a syntypic series of four female specimens under the name Derelomus fasciatus and bearing the labels “Usambara” and “Kraatz” as reported in the original description was located. One of the specimens of this series was designated as the lectotype for Derelomus fasciatus Hartmann, 1904 [here designated] and was labelled accordingly. Derelomus fasciatus as treated here may be a complex of closely related species or lineages in process of speciation. The Tanzanian and South African populations show slight differences (based on the very few specimens available); in the latter, the rostrum is slightly shorter and less downcurved, the pronotum is more convex laterally and the antennal club is pale brown. Also, a single female from South Africa (JHAR01252) exhibits a contrasting body and rostrum shape with specimens of the same series. This specimen likely corresponds to a distinct species.