Derelomus pallidus Fåhraeus, 1844

Derelomus pallidus Fåhraeus, 1844

Fig. 10 View Fig

Derelomus pallidus Fåhraeus, 1844: 95 .

Derelomus pallidus Hartmann, 1904: 407 . Syn. nov.

Derelomus hartmanni Klima, 1934: 134 (replacement name for D. pallidus Hartmann, 1904 ; preoccupied name). Syn. nov.

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

Diagnosis

Derelomus pallidus can be distinguished in the combination of small body size (up to 2.5 mm), a short rostrum (at most as long as the pronotum in lateral view; Fig. 10B View Fig ), the uniformly pale brown body integument (the darker triangular area as base of the elytra in this species is due to the dark color of the tergites partly masked by the wings in repose condition, some specimens have the head and rostrum slightly darker) and the simple claws. It can be distinguished from other species in the D. pallidus group by its comparatively short rostrum ( Figs 10B View Fig , 11B–F). The general appearance of this species is close to another one in Derelomini : Ebenacobius rectirostris Haran, 2022 , but in the latter, the interocular space bears a groove (absent in Derelomus ) and the body of the penis lacks a thickening near the base (synapomorphy in Derelomus ). In our current knowledge, D. pallidus is the only species of Derelomus associated with the flowers of Euclea L. ( Ebenaceae ). GenBank accession numbers for the corresponding DNA barcodes: ON553416 View Materials / ON553430 View Materials /PV698476–77–78–79.

Material examined

Lectotype of Derelomus pallidus Fåhraeus, 1844 (here designated)

REPUBLIC OF SOUTH AFRICA • ♀; “ Cap . b.; sp. [ Cape of Good hope, South Africa]” “Drége” “3757; E91+” “Naturhistorika Riksmuseet; Stockholm; Loan no 813/06” “Lectotype ♀; Derelomus ; pallidus ; Fåhraeus 1844; Haran des. 2025”; NHRS.

Lectotype of Derelomus pallidus Hartmann, 1904

TANZANIA • ♂; “ ♂ ” “ Usambara; Kraatz ” “47” “ Derelomus ; pallidus Htm ” “Coll. J. Faust; Ankauf 1900” “Staatl. Museum für; Tierkunde Dresden” “Lectotype ♀; Derelomus ; pallidus ; Hartmann, 1904; Haran des. 2025” “ Derelomus ; hartmanni ; Klima, 1934; Haran 2025” “ Derelomus ; pallidus ; Fåhraeus 1844; Haran 2025”; MTD.

Paralectotypes

TANZANIA • 4 ♀♀; same collection data as for lectotype of Derelomus pallidus Hartmann, 1904 ; MTD.

Other material

ANGOLA • 1 ♂, 1 ♀; Tundavala; 14°50′39″ S, 13°24′54″ E; 27–29 Mar. 1972; at lights; NHMUK. GoogleMaps

KENYA • 1 ♀; Mount Kenya , West slope , Amboni Rivir ; 0°20′13″ S, 36°54′10″ E; Jan.–Feb. 1912; Alluaud and Jeannel coll.; MNHN GoogleMaps • 1 ♀; Nairobi 1°20′17″ S, 36°47′28″ E; Jan. 1938; A.F.J. Gedye coll.; NHMUK GoogleMaps .

REPUBLIC OF SOUTH AFRICA – Eastern Cape Province • 2 ♂♂, 30 specs (preserved in ethanol); Byra river mouth ; 33°12′07″ S, 18°04′55″ E; 14 Jul. 2019; J. Haran coll.; beating flowers of Euclea L. sp. ( Ebenaceae ); JHAR02380 ; CBGP GoogleMaps • 1 ♂, 1 ♀; same collection data as for preceding; MCZR GoogleMaps • 2 ♂♂, 2 ♀♀; Kabeljous Nature Reserve; 33°59′42″ S, 24°56′00″ E; Dec. 2009; Ş. Procheş coll.; beating flowers of Diospyros dichrophylla (Gand.) De Winter ( Ebenaceae ); JHAR04163 ; CBGP GoogleMaps • 4 ♂♂; Colchester; 33°42′25″ S, 25°50′38″ E; Ş. Procheş coll.; on Euclea sp. ( Ebenaceae ); JHAR07429 ; CBGP GoogleMaps • 2 ♂♂, 2 ♀♀; Gamtoos; 33°57′29″ S, 25°02′17″ E; Ş. Procheş coll.; beating flowers of Diospyros dichrophylla ( Ebenaceae ); JHAR07428 ; CBGP GoogleMaps • 2 ♂, 7 ♀♀; Kenton-on-Sea ; 33°41′06″ S, 26°40′12″ E; 9 Sep. 1951; E. Mc. Callan coll.; on sand; BM-1963-286 ; NHMUK GoogleMaps • 1 ♀; Port St Johns ; 31°37′46″ S, 29°32′31″ E; 15–31 May 1923; R.E. Turner coll.; NHMUK. GoogleMaps – KwaZulu-Natal Province • 1 ♀; New Germany Nature Reserve , Protea Ridge ; 29°48′43″ S, 30°53′28″ E; Jul. 2011; Ş. Procheş coll.; on flowers of Diospyros L. sp. ( Ebenaceae ); JHAR07431 ; CBGP. GoogleMaps – Northern Cape Province • 1 ♂, 1 ♀, 40 specs (preserved in ethanol); Oorlogskloof Nature Reserve ; 31°27′00″ S, 19°04′05″ E; 4 Aug. 2023; J. Haran; beating flowers of undet. bush; JHAR05784 ; CBGP. GoogleMaps – Western Cape Province • 2 ♂♂, 2 ♀♀; Cape Town; 33°55′12″ S, 18°24′36″ E; Aug. 1893; SAMC GoogleMaps • 2 ♂♂, 1 ♀, 20 specs (preserved in ethanol); West Coast National Park ; 33°12′07″ S, 18°04′55″ E; 3 Mar. 2018; J. Haran coll.; beating flowers of Euclea racemosa L. ( Ebenaceae ); JHAR00820 ; CBGP GoogleMaps • 1 ♀, 4 specs (preserved in ethanol); Stellenbosch; 33°56′28″ S, 18°52′19″ E; 28 Jul. 2018; J. Haran coll.; beating flowers of Searsia ( Anacardiaceae ); JHAR01361 ; CBGP GoogleMaps • 1 spec. (preserved in ethanol); Paradysekloof ; 33°58′09″ S, 18°52′38″ E; 30 Mar. 2019; J. Haran; on white flowering bush; CBGP GoogleMaps • 6 specs (preserved in ethanol); Du Toitskloof Pass ; 33°43′15″ S, 19°04′23″ E; 21 Apr. 2018; J. Haran; beating fynbos; JHAR00920 ; CBGP GoogleMaps • 3 specs (preserved in ethanol); Cape Peninsula, Cape of Good Hope; 34°21′12″ S, 18°28′24″ E; 15 Apr. 2018; J. Haran; beating flowers of Euclea racemosa ( Ebenaceae ); JHAR00921-01 ; CBGP GoogleMaps • 1 spec. (preserved in ethanol); Franschoek Pass ; 33°54′15″ S, 19°09′26″ E; 4 Jun. 2018; J. Haran; beating flowers of Euclea racemosa ( Ebenaceae ); CBGP GoogleMaps • 7 specs (preserved in ethanol); Arniston; 34°40′30″ S, 20°13′52″ E; 21 Mar. 2019; J. Haran; beating flowers of Euclea racemosa ( Ebenaceae ); JHAR02253 ; CBGP GoogleMaps • 1 ♀, 1 spec. (preserved in ethanol); Elandsbay; 32°19′49″ S, 18°18′58″ E; 6 Aug. 2023; J. Haran; beating flowers of Euclea racemosa ( Ebenaceae ); JHAR05798 ; CBGP GoogleMaps • 10 specs (preserved in ethanol); Simonsberg; 33°53′10″ S, 18°55′30″ E; 7 Dec. 2019; J. Haran; beating fynbos; JHAR03096 ; CBGP GoogleMaps • 2 ♀♀; Betty′s Bay ; 34°20′24″ S, 18°55′12″ E; Ş. Procheş coll.; beating flowers of Diospyros lycoides Desf. ( Ebenaceae ); JHAR07427 ; CBGP GoogleMaps • 1 ♀; Standford; 34°26′10″ S, 19°26′49″ E; Dec. 2009; M. Gibson coll.; on Acacia saligna (Labill.) H.L. Wendl. ( Fabaceae ); JHAR07430 ; CBGP GoogleMaps • 2 ♂♂, 2 ♀♀; Mossel Bay ; 34°12′04″ S, 22°05′56″ E; Apr. 1921; R.E. Turner coll.; “165”; NHMUK GoogleMaps • 4 ♂♂, 2 ♀♀; Mossel Bay; 34°12′04″ S, 22°05′56″ E; Jun. 1921; R.E. Turner coll.; NHMUK GoogleMaps • 1 ♀; Mossel Bay ; 34°12′04″ S, 22°05′56″ E; Sep. 1921; R.E. Turner coll.; NHMUK GoogleMaps • 1 ♀; Mossel Bay ; 34°12′04″ S, 22°05′56″ E; Oct. 1921; R.E. Turner coll.; NHMUK GoogleMaps • 2 ♂♂, 4 ♀♀; Breede River , Heidelberg Dist.; 33°32′21″ S, 19°12′04″ E; 6 Feb. 1932; R.E. Turner coll.; NHMUK GoogleMaps • 1 ♀; Cape Town; 33°55′12″ S, 18°24′36″ E; 1 Sep. 1901; Cledoux coll.; USNM GoogleMaps • 1 ♀; Ceres; 33°22′04″ S, 19°18′21″ E; 2–21 Mar. 1921; R.E. Turner coll.; NHMUK GoogleMaps • 1 ♀; Worcester; 33°37′51″ S, 19°27′18″ E; Sep. 1928; R.E. Turner coll.; NHMUK. GoogleMaps

UGANDA • 1 ♂; Kawanda; 0°25′31″ N, 32°32′24″ E; 15 Feb. –6 Mar. 1958; P. Walley; mercury vapor light trap; NHMUK. GoogleMaps

Redescription ( ♂)

MEASUREMENTS. Body length 1.9–2.4 mm.

COLOR. Body integument unifo.rmly pale brown, head and club usually darker; dark color of tergites visible elytra at base, forming darker reversed triangle. Vestiture of dorsum made of minute white, recumbent setae, integument glabrous in appearance.

HEAD. Rostrum as long as pronotum in lateral view, moderately and regularly downcurved; in dorsal view 3 to 4× as long as wide, integument densely punctate, forming 5 carinae, more or less distinct; antennae inserted near apical ¼ of length; head capsule densely punctate in dorsal view; eyes very 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, 2 longer than wide, 3–7 transverse.

PRONOTUM. Isodiametric to moderately wider than long (W: L ratio: 1–1.20), widest near base, 0.78× as wide there as elytra at humeral angles, lateral carina forming small obtuse tooth slightly beyond middle of length; sides subparallel or slightly converging apicad in basal ⅔ of length, converging or converging more distinctly in apical ⅓, apical constriction shallow but visible; integument with large circular punctures, arranged in irregular manner, space between punctures dull, narrower or wider than diameter of punctures.

METATHORAX. Metanepisterna with scattered non-overlapping white setae.

ELYTRA. Longer than wide (W: L ratio: 0.67); sides slightly convex, widest near middle of length; humeri raised; apex jointly rounded; striae with punctures as wide as or slightly narrower than interstriae; interstriae slightly convex, 9 raised into carina; scutellar shield rounded, bearing recumbent setae.

ABDOMEN. Underside covered with minute recumbent whitish setae, not contiguous. Stridulatory plate with lines of about 10 granules, ⅔× as long as median line from base; granules space between granules as wide as or narrower than diameter of granules. Central sclerotized area wide and regularly rounded apically.

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

TERMINALIA. Body of penis moderately elongate (W: L ratio: 0.28), slightly less than 2 × as long as apodemes; sides regularly and moderately convex in dorsal view, widest near middle of length; converging more strongly in apical ¼, apex rounded; in lateral view curvature stronger in basal 2/5 of length, width narrowing from apical 1/5 middle of length to apex; apex curved upward ( Fig. 10C View Fig ).

Sexual dimorphism

Females can be distinguished from males by the rostrum which is slightly longer in lateral view.

Variation

The rostrum of this species shows a sizable variability of size and curvature, but this variation is not associated with genetic divergence ( Fig. 33 View Fig ).

Life history

Adults of this species are found in prodigious numbers on inflorescences in anthesis of Euclea racemosa ( Ebenaceae ), which likely constitutes its host plant. They accidentally visit the flowers of other plants and were sporadically recorded on Fabaceae and Anacardiaceae . A specimen was also intercepted in the port of Los Angeles ( USA) on imported Phylica L. sp. ( Rhamnaceae ) in 2002 (USNM). The records on flowers of Diospyros L. species would deserve further observations in order to verify if this species can develop on Ebenaceae out of Euclea . Derelomus pallidus was found in sympatry with Ebenacobius san Haran, 2022 on Euclea racemosa and with Ebenacobius hessei Haran, 2022 on an unidentified Euclea ( Haran et al. 2022b) . Note that multi species assemblage of weevils on white and pendulous inflorescences of dioecious plants like Euclea agree with the typical patterns of brood-site pollination mutualism ( Haran et al. 2023a). Adults were recorded from January to March in East Africa ( Kenya) and almost all year round in southern Africa ( Angola and Republic of South Africa, not recorded in January, May and October–November).

Distribution

This species is distributed in southern and East Africa ( Angola, Kenya, Republic of South Africa, Tanzania and Uganda). The putative host plant, Euclea racemosa ( Ebenaceae ), ranges from the Western Cape Province of the Republic South Africa up to the southern part of the Arabian Peninsula.

Remarks

In the Fåhraeus collection housed at NHRS, a female specimen under the name Derelomus pallidus and fitted with the labels “ Cap . b.; sp.[cape of good hope]” and “Drége” (as reported in the original description) was located. This specimen is the lectotype [here designated] for Derelomus pallidus Fåhraeus, 1844 and was labelled accordingly. In the Faust-Hartmann collection housed at MTD, a syntypic series of specimens ( 1 ♂, 4 ♀♀) under the name Derelomus pallidus and bearing the labels “Usambara” and “Kraatz” as reported in the original description was located. The male specimen of this series was designated as the lectotype for Derelomus pallidus Hartmann, 1904 [here designated] and was labelled accordingly. The name Derelomus pallidus Hartmann, 1904 was replaced by Derelomus hartmanni Klima, 1934 in the Catalogus Coleopterorum ( Klima 1934) , the former combination being preoccupied by Derelomus pallidus Fåhraeus, 1844 . Detailed examinations of external and internal morphology of the type material of Derelomus pallidus Fåhraeus, 1844 and Derelomus hartmanni Klima, 1934 as well as specimens related to these species from various localities showed no significant differences. The rostrums in the lectotype and the paralectotypes of D. hartmanni are slightly longer and more downcurved than in the lectotype of D. pallidus , but the examination of long series of specimens of D. pallidus shows that the shape of the rostrum is quite variable at population level, a feature not associated with genetic differences (specimens included in Haran et al. 2022a were variable for that feature). In addition, the host plant of D. pallidus ( Euclea racemosa L.) is widely distributed in austral and eastern Africa, and occurs where D. hartmanni was recorded ( Tanzania). As a result of this, the names Derelomus pallidus Hartmann, 1904 and Derelomus hartmanni Klima, 1934 are proposed as junior synonyms of Derelomus pallidus Fåhraeus, 1844 [new synonymies].