Derelomus signatus Gyllenhal, 1836

Derelomus signatus Gyllenhal, 1836

Fig. 2 View Fig

Derelomus signatus Gyllenhal, 1836: 630 .

Derelomus signatus – Haran et al. 2022a (erroneous identification, see D. schoedli ).

Diagnosis

Derelomus signatus can be distinguished by the combination of white scales on the lateral carina of the pronotum, the narrow pronotum (W:L ratio: 1.25), two transverse bands or lines of dark spots on the elytra and black club. It is closest to D. abyssinicus , but in the latter species the rostrum is almost straight in lateral view ( Fig. 5B–C View Fig ) and the elytra only exhibit one transverse dark band ( Fig. 5A View Fig ).

Material examined

Neotype (here designated)

ZAMBIA • ♂; “Zambia 1050m; Lukulu, Barotse Floodplain ; S14°12′42″; E23°19′06″ ” “ 9.xi.13 Light trap; Leg. Smith, R., Takano, H.; & Oram, D. ” “BMNH(E); 2016-251” “ NHMUK 010804484 About NHMUK ” “NEOTYPE; Derelomus signatus ; Gyllenhal, 1836; Haran des. 2025”; NHMUK.

GoogleMaps

Other material

REPUBLIC OF SOUTH AFRICA – KwaZulu-Natal Province • 2 ♀♀; Gingindlovu; 29°1′8″ S, 31°35′14″ E; 22 May 1922; R.E. Turner coll.; NHMUK GoogleMaps • 1 ♀; Gingindlovu; 29°1′8″ S, 31°35′14″ E; 29 Apr. 1926; R.E. Turner coll.; NHMUK GoogleMaps • 1 ♀; Gingindlovu; 29°1′8″ S, 31°35′14″ E; 9 Jun. 1926; R.E. Turner coll.; NHMUK GoogleMaps • 1 ♀; Pondolandia Nature Reserve ; 31°20′31″ S, 29°15′32″ E; 5–30 Apr. 1923; R.E. Turner coll.; NHMUK GoogleMaps • 2 ♀♀; Malvern; 29°53′06″ S, 30°54′48″ E; Aug. 1897; G.A.K. Marshall coll.; NHMUK. GoogleMaps – Eastern Cape Province • 1 ♀; Dwesa forest reserve ; 32°18′15″ S, 28°49′34″ E; 11 Dec. 1979; Endrödy-Younga coll.; flowering Acacia [ Vachellia ] Mill.; E-Y: 1674; TMSA GoogleMaps • 2 ♀♀; Somerset East [ Kwanojoli]; 32°42′57″ S, 25°34′16″ E; 10–22 Dec. 1930; R.E. Turner coll.; NHMUK GoogleMaps • 2 ♀♀; Katberg; 32°29′31″ S, 26°40′45″ E; 1–15 Jan. 1933; R.E. Turner coll.; NHMUK. GoogleMaps

ETHIOPIA • 1 ♀; Mulu, above Muger Valley ; 9°17′06″ N, 40°50′28″ E; 18–23 Nov. 1926; H. Scott coll.; circa 8000 ft; NHMUK GoogleMaps .

KENYA • 2 ♀♀; 90 km from Nairobi (no precise locality); 26 Mar. 1990; D. Hongo coll.; adults collected on Vachellia seyal (Delile) P.J.H.Hurter ; NHMUK • 1 ♀; 90 km from Nairobi (no precise locality); 22 Mar. 1990; D. Hongo coll.; adults collected on Vachellia hockii (De Wild.) Seigler & Ebinger ; NHMUK.

Redescription ( ♂)

MEASUREMENTS. Body length 2.5 mm.

COLOR. Body integument pale brown, head and pronotum darker, club black, elytra with two transverse oblique lines of dark spots on even interstriae; vestiture of dorsum made of white setiform scales, forming one row on each interstria, more visible on odd interstriae.

HEAD. Rostrum as long as pronotum in lateral view, moderately and regularly downcurved; in dorsal view 3 × as long as wide, integument densely punctate, with 5 carinae, covered with short suberect whitish setae oriented transversally; antennae inserted near apical ¼ of length; head capsule coarsely punctate in dorsal view, with contiguous suberect whitish scales forming two tufts near eyes; eyes convex, exceeding lateral curve of head capsule in dorsal view; antennal funicle with first segment 2× as long as wide, equal in length to segments 2–4 together, 3–7 transverse.

PRONOTUM. Wider than long (W: L ratio: 1.25), widest near base, 0.77× as wide there as elytra at humeral angles, lateral carina forming obtuse angle beyond middle of length; sides abruptly converging in apical 1/5, apical constriction deep and visible; integument with large circular punctures, space between punctures dull, narrower than or as wide as diameter of punctures; setae recumbent, cover less dense near basal and apical margins and along median line.

METATHORAX. Metanepisterna with scarce setiform scales.

ELYTRA. Elongate (W: L ratio: 0.62); sides subparallel in basal ⅔, widest near middle of length; humeri raised, with tuft of white setiform scale; apex jointly rounded, notched at apex of suture; striae with punctures narrower than interstriae; odd interstriae raised; scutellar shield rounded, black, glabrous.

ABDOMEN. Underside covered with minute recumbent whitish setae, not contiguous. Stridulatory plate with lines of 6 granules, 0.8× as long as median line from base; central sclerotized area regularly rounded laterally.

LEGS. Profemora moderately thickened near middle of length; protibiae with external margin straight, internal slightly bisinuate; claws appendiculate.

TERMINALIA. Body of penis elongate (W: L ratio: 0.17); sides straight in dorsal view, widest at base, converging regularly apicad from apical 1/5 of length, apex forming a spatula; in lateral view curvature stronger in basal ½ of length, width narrowing regularly from middle of length to apex; apex curved upward; apodemes very short, less than 0.2× the length of penis body ( Fig. 2D View Fig ).

Sexual dimorphism

Females can be distinguished from males by the rostrum which is slightly longer and more downcurved in lateral view ( Fig. 2C View Fig ), and by their more convex elytra.

Variation

Scale cover and patterns on the elytra are variable in this species. In some specimens, the vestiture of the pronotum and elytra is very short and hardly visible. The dark apical band on the elytra may consist of a wide transverse band, only interrupted on the suture or only two dots on interstriae 4 and 7. All specimens examined show two transverse bands on each elytron, the one near the middle of the length, sometimes pale ocher, poorly contrasting with the rest of the integument. The condition of the appendiculate claws is seemingly variable in this species, this feature was not used for the diagnosis of this species.

Life history

Specimens were collected on Vachellia hockii , V. seyal and Vachellia sp. ( Fabaceae ) and using light traps. Adults were recorded from March to June and from November to December.

Distribution

Ethiopia, Kenya, Republic of South Africa ( Eastern Cape and KwaZulu-Natal provinces) and Zambia.

Remarks

Despite intensive searches, we could not locate the type of Derelomus signatus Gyllenhal, 1836 . It is absent from Schoenherr’s and Chevrolat’s collections housed at NHRS, while a label bearing this species name at the bottom of the boxes indicates that a specimen used to be located there. We also searched among the material borrowed by the late G. Kuschel from various institutions, without success. In addition, in a preliminary manuscript left by him, G. Kuschel stated that he did not examine the type of this species, suggesting that the specimen was unavailable when he undertook his work on this genus (circa 2007). The original type is therefore considered as lost. In order to stabilise the nomenclature, and given the homogeneity of the D. signatus species group, a neotype is here designated (ICZN art. 75). The original description given by Gyllenhal provides diagnostic features: “[…] rostrum capite dimidio longius, validum, valde arctuatum [rostrum 1.5× as long as head, stocky and strongly downcurved]. […] Antennae testaceae, clava nigra [antennae reddish brown, club black]. […] sutura interstitiisque alternis paulo elevatioribus, laevibus; […] lineolis nonnullis brevibus, sparsis, brunneis, notata [odd and sutural interstriae slightly raised, smooth; with few scattered brown spots].” In southern Africa where this species was described, these features apply only to one Derelomus morphospecies for which one male from Zambia and 16 females from Southern and Eastern Africa are available in the material examined. The male specimen of this series is designed as the neotype for the species name Derelomus signatus Gyllenhal, 1836 [here designated] and was labelled accordingly [deposited at NHMUK]. A redescription of this species is provided to report the diagnostic features with closely related species. Due to misidentifications in reference collections, the specimen included in Haran et al. (2022b) under the name D. signatus (JHAR01036) is in fact D. schoedli Rheinheimer, 2005 .