Derelomus languidus Fåhraeus, 1844

Derelomus languidus Fåhraeus, 1844

Fig. 20 View Fig

Derelomus languidus Fåhraeus, 1844: 93 .

Derelomus rectirostris Hustache, 1937: 218 . Syn. nov.

Prosoestus rectirostris – Lepesme 1947 (key, biology).

Diagnosis

Derelomus languidus can be distinguished by its very long rostrum, almost ( ♂) or equal ( ♀) to 2× the length of pronotum in lateral view, and the uniform pale brown color of the integuments, or only with darker shadings on the sides and at the apex of the elytra. This species is similar in size and general aspect to D. strangulatus sp. nov., but in the latter the side of the pronotum is deeply strangled apically (only narrowed in D. languidus ).

Material examined

Lectotype of Derelomus languidus Fåhraeus, 1844 (here designated)

REPUBLIC OF SOUTH AFRICA • ♂; “TYPUS [red label]” “cap. b. sp. [cape of good hope]; Drège ” “LECTOTYPE ♂; Derelomus ; languidus ; Fåhraeus, 1844; Haran des. 2025” “ Derelomus ; languidus ; Fåhraeus 1844; Haran des. 2025” “Naturhistorika Riksmuseet; Stockholm; Loan no 136/03”; NHRS.

Holotype of Derelomus rectirostris Hustache, 1937

DEMOCRATIC REPUBLIC OF CONGO • ♂; “♂” “Holotypus [red label]” “Récolté dans; fruits de; Phoenix ” “Musée du Congo; Rutshuru [ 1°11′04″ N 29°27′14″ E]; - I-1937; J. Ghesquière; 3651” “dét.; KK; 3245” “ Derelomus ; rectirostris m.[me]; Hustache det.” “Holotype ♂; Derelomus ; rectirostris ; Hustache, 1937; Haran des. 2025” “ Derelomus ; languidus ; Fåhraeus, 1844; Haran det. 2025”; RMCA.

GoogleMaps

Paralectotypes

REPUBLIC OF SOUTH AFRICA • 1 ♀; Cape of Good Hope; Drège coll.; NHRS • 1 ♀; Cape de Bonne espérance [ Cape of Good Hope]; Schoenherr 1836; cotype D. languidus ; MNHN.

Paratypes ( D. rectirostri s )

DEMOCRATIC REPUBLIC OF CONGO • 1 (sex not determined, head and pronotum missing); Rutshuru; 1°11′04″ N, 29°27′14″ E; Jan. 1937; J. Ghesquière coll.; from fruits of Phoenix sp. ; 3651; RMCA.

GoogleMaps

Other material

DEMOCRATIC REPUBLIC OF CONGO • 3 ♀♀; Rutshuru; 1°11′04″ N, 29°27′14″ E; May 1937; J. Ghesquière coll.; RMCA GoogleMaps • 1 ♂, 1 ♀; South Kivu, Mulungu; 2°54′32″ S, 27°55′34″ E; 30 Sep. 1938; Hendrickx coll.; A.663; RMCA GoogleMaps • 1 ♂, 1 ♀; same data as for preceding; NHMUK. GoogleMaps

REPUBLIC OF SOUTH AFRICA • 2 ♀♀; South Africa [no precise locality]; 1905; Sharp coll.; NHMUK • 2 ♂♂, 1 ♀; [no precise locality]; Péringey coll.; NHMUK • 1 ♀; [no precise locality]; NMB. – Western Cape Province • 1 ♀; 1 (sex not determined); Cap . b. spé. [ Cape of Good Hope], “Kapland”; NMB. – Eastern Cape Province • 2 ♂♂, 3 ♀♀; Kentani; 32°30′29″ S, 28°19′37″ E; 1907; A. Pegler coll.; SAM-COL-A050315 ; SAMC GoogleMaps • 1 ♀; same collection data as for preceding; SAM-COL-A050314 ; SAMC • 3 ♂♂, 3 ♀♀; Mbotyi, 31°27′11″ S, 29°44′49″ E; Dec. 2009; Ş. Procheş coll.; on female inflorescences of Phoenix reclinata ; JHAR04159 ; CBGP. GoogleMaps – KwaZulu-Natal Province • 1 ♂, 3 ♀♀; Mtwalume; 30°29′41″ S, 30°37′27″ E; 18 Jun. 1921; TMSA GoogleMaps • 1 ♀; “natal” [no precise location]; 1930; Sicard coll.; MNHN • 3 ♂♂, 3 ♀♀; Empangeni; 28°46′06″ S, 31°53′07″ E; 2 Apr. 1923; reared from seeds of Phoenix reclinata ; NHMUK GoogleMaps • 1 ♀; Empangeni; 28°46′06″ S, 31°53′07″ E; 12 May 1923; C.P. Lounsbury coll.; reared from seeds of palm, Phoenix ?; NHMUK GoogleMaps • 1 ♂; Umtentweni; 30°43′14″ S, 30°28′16″ E; Jul. 1951; A.L. Capener; NHMUK. GoogleMaps

Redescription ( ♂)

MEASUREMENTS. Body length 3.2–4.0 mm.

COLOR. Body integument pale brown, rostrum, sides and apex of elytra sometimes darker; dorsum glabrous in appearance, bearing minute whitish setae only visible on sides at high magnification.

HEAD. Rostrum distinctly longer than pronotum in lateral view (1.6×), only slightly downcurved in lateral view; in dorsal view about 7× as long as wide, integument densely and finely punctate, forming 5 superficial longitudinal carinae from eyes to antennal insertion, median carina broader than others, split in two before antennal insertion; covered with scattered minute recumbent and non-contiguous whitish setae oriented transversally; antennae inserted near apical ⅓ of length in lateral view; head capsule coarsely punctate in dorsal view, puncture contiguous; forehead glabrous, with slight cuticular depression in middle; eyes convex, exceeding moderately lateral curve of head capsule in dorsal view; antennal funicle with segment 1 as long as 2+3, 3× as long as wide, 3–7 longer than wide.

PRONOTUM. Transverse (W: L ratio: 1.35), widest near base or on basal ⅔ length, slightly narrower there than elytra at humeral angles (0.85 ×); sides slightly convex, subparallel or converging regularly apicad in in basal ⅔, converging abruptly in apical ⅓, lateral carina forming small constriction and tooth beyond middle of length, apical constriction shallow, about as wide as width of scape at apex; integument punctate, space between punctures dull, micropunctate, generally narrower than diameter of a puncture on dorsum; setae shorter than diameter of a puncture, only visible laterally.

ELYTRA. Elongate (W: L ratio: 0.68); sides slightly convex, subparallel in basal ½, widest near middle of length; humeri raised; apex rounded, contiguous or not contiguous; striae with punctures about 2× narrower than width of interstriae; interstriae slightly convex, 9 raised into carina; scutellar shield rounded, glabrous.

ABDOMEN. Underside covered with minute recumbent whitish setae, not contiguous. Stridulatory plate with series of 2–4 ill-defined granules, forming short lines about 0.5 × as long as length of median area; apex of median area rounded ( Fig. 20E View Fig ).

LEGS. Profemora moderately thickened near middle of length; protibiae with external margin straight, meso- and metatibiae slightly curved outward in apical half, internal margin of protibiae bisinuate, claws simple.

TERMINALIA. Body of penis elongate (W: L ratio: 0.23), about 3.5× as long as apodemes, widest near base in dorsal view; sides slightly concave, narrowest beyond middle of length, widening apicad in apical ⅓, apex rounded; in lateral view curvature slightly stronger in basal ½ of length, width narrowing apicad from in apical ⅓ of length ( Fig. 20D View Fig ).

Sexual dimorphism

The rostrum of females is distinctly longer (2 × as long as pronotum in lateral view) and more downcurved than in males. The antennae are inserted near the middle of the length (near the apical ⅓ in males; Fig. 20B–C View Fig ).

Life history

Derelomus languidus develops in the fruits of Phoenix reclinata ( Arecaceae ; Lepesme 1947), adults are found on female inflorescences of this palm. This species is active in December and January, and from April to July.

Distribution

In our current knowledge, this species is known from the Eastern part of the Democratic Republic of Congo and from the coastal regions of the Eastern Cape and KwaZulu-Natal Provinces of the Republic of South Africa. Its host is widely distributed in continental Africa.

Remarks

In the collection housed at NHRS, a male and a female specimen under the name Derelomus languidus “Schr. Fhr ” and bearing a label of the type locality [Cape of Good Hope] were located. The male specimen of this syntypic series (fitted with a red type label) is designated as the lectotype for Derelomus languidus Fåhraeus, 1844 [here designated] and was labelled accordingly. The examination of the series of Derelomus rectirostris Hustache, 1937 ( Democratic Republic of Congo) revealed no significant morphological difference with the series of Derelomus languidus Fåhraeus, 1844 from the Republic of South Africa. The specimens from the Democratic Republic of Congo are slightly smaller (about 3 mm long versus 4 in D. languidus from the Republic of South Africa), the antennae are inserted slightly beyond the apical ⅓ of the length and the pronotum is less transverse. However, these variations are common between populations from central-eastern and southern Africa in Derelomus and the examination of the internal structures revealed no significant differences between the two series. As a result, the species name Derelomus rectirostris Hustache, 1937 is proposed as a junior synonym [new synonymy] of Derelomus languidus Fåhraeus, 1844 . This species shows some affinities with the D. nigrovariegatus group (large size, arrangement of granules on the stridulatory plate and development on inflorescences of P. reclinata ) but it is kept in a distinct group here due to the peculiar shape of the body of the penis, the size of the apodemes, the absence of a comb of seta on the protibiae of the males and the prosternum uniformly pale brown.