Derelomus piriformis ( Hoffmann, 1938 )

Derelomus piriformis ( Hoffmann, 1938)

Fig. 25 View Fig

Pseudoderelomus piriformis Hoffmann, 1938a: 107 .

Derelomus kocheri Hoffmann, 1957: 83 . Syn. nov.

Neoderelomus piriformis – Hoffmann 1938b (genus name preoccupied). — Abbazi & Osella 1992 (distribution). — Piry & Gompel 2002 (description of larva, biology, distribution). — Alonso-Zarazaga & Lyal 1999 (distribution). — Meekijjaroenroj & Anstett 2003 (biology).

Derelomus piriformis – Franz 2006: 275 (new combination). — Haran et al. 2022a (phylogenetic relationship).

Diagnosis

In the D. ephippiger group, this species can be distinguished by the combination of a uniformly pale brown integument, and males with the elytra widest beyond the middle of the length, protibiae with an internal comb of elongate setae and a comparatively moderately long rostrum (4.5–5× as long as wide in dorsal view). Females can be distinguished by the distinct narrowing at the base of the rostrum. Derelomus piriformis is closely related and sometimes sympatric with D. chamaeropis , but in the latter species, males have the elytra slightly convex in dorsal view and the protibiae lacking an internal comb (very convex elytra and protibiae with a comb of setae in D. piriformis ) and females have a shorter and wider rostrum ( Fig. 24D View Fig ). Uncorrected p -distances between these species range from 8.0 to 8.8%. GenBank accession number for the corresponding DNA barcode: OK188814 View Materials .

Material examined

Lectotype of Pseudoderelomus piriformis (here designated)

MADEIRA • ♂; “ Funchal; Madère; 15.8.1936; Balachowsky [Alferd Balachowsky, french entomologist]” “ Pseudoderelomus ; piriformis ; Hoffm.” “genotype; TYPE” “TYPE[red label]” “Museum Paris; 1968; Col. A. Hoffmann ” “Lectotype ♂; Derelomus piriformis ; ( Hoffmann, 1938); J. Haran des. 2025”; MNHN.

Holotype of Derelomus kocheri Hoffmann, 1957

MOROCCO • ♀; “ Rabat (Maroc); ( Kocher) 10. 52 ( Oct. 1952]” “ Derelomus ; kocheri m.[me, handwritten by Hoffmann]; A. Hoffmann det.” “Typus [red label]” “Museum Paris; 1968; Col. A. Hoffmann ” “Holotype ♀; Derelomus ; kocheri ; Hoffmann, 1957; J. Haran 2025” “ Derelomus ; piriformis (Hoff.) ; Haran det. 2024”; MNHN.

Paralectotype

MOROCCO • 1 ♂; Rabat ; 34°02′47.0″ N, 6°50′25.0″ W; 1 Feb. 1930; Bremond coll.; MNHN.

GoogleMaps

Other material

FRANCE • 4 ♂♂, 12 ♀♀; Hérault, Aéroport de Maugio ; 43°33′57″ N, 3°57′00″ E; 5 Nov. 2000; S. Piry coll.; male inflorescences of Phoenix canariensis ; MNHN GoogleMaps • 2 ♂♂, 1 ♀; Montpellier, Hopital Gui de Chauliac ; 43°37′56″ N, 3°51′18″ E; 1 Nov. 2000; S. Piry coll.; male inflorescences of Phoenix canariensis ; CBGP GoogleMaps • 2 ♂♂, 1 spec. (preserved in ethanol); Corsica, Macinaggio; 42°57′32″ N, 9°27′10″ E; 8 Oct. 2015; J. Haran coll.; male inflorescences of P. canariensis ; CBGP GoogleMaps • 1 ♀; Le Cannet; 43°34′41″ N, 7°00′26″ E; 8 Aug. 1954; P. Bonadona coll.; PW GoogleMaps • 1 ♂; La Garde; 43°07′30″ N, 6°01′19″ E; 9 Jul. 1953; P. Veyret; PW GoogleMaps • 1 ♀; La Garde; 43°07′30″ N, 6°01′19″ E; 7 Nov. 1952; P. Veyret; PW GoogleMaps • 1 ♂, 2 ♀♀; Toulon; 43°08′13″ N, 5°55′26″ E; Dec. 1936; P. Veyret; PW GoogleMaps • 1 ♂; Toulon; 43°08′13″ N, 5°55′26″ E; Nov. 1936; P. Veyret; PW GoogleMaps • 1 ♀; Nice, Jardin Alsace Lorraine ; 43°41′52″ N, 7°15′26″ E; 28 Feb. 1999; S. Piry coll.; ex. flowers of Phoenix sp. ; CBGP. GoogleMaps

ITALY • 3 ♂♂, 3 ♀♀; Western Liguria, Varigotti; 44°10′52″ N, 8°23′54″ E; 4 Oct. 1966; G. Bartoli coll.; Phoenix sp. ; JHAR07418 ; CBGP GoogleMaps • 1 ♂; Roma, Tuscolano ; 41°52′12″ N, 12°32′18″ E; 17 Sep. 1946; L. Magnano coll.; at light; NHMUK. GoogleMaps

MOROCCO • 1 ♀; Oujda; 34°40′23″ N, 1°54′18″ W; 13 Dec. 1998; G. Chavanon coll.; on the ground; JHAR7419 ; CBGP. GoogleMaps

PORTUGAL • 1 ♂, 1 ♀; Porto Santo Island [ Madeira archipelago]; 33°03′50″ N, 16°19′26″ W; 3 Apr. 2015; J-D. Chapelin Viscardi coll.; male inflorescences of P. canariensis ; JHAR2983 ; CBGP. GoogleMaps

SPAIN • 1 ♀; Las Palmas de Gran Canaria, Santa Catalina area ; 28°08′21″ N, 15°26′11″ W; 10 Mar. 1903; P. Lesne coll.; emerged from plant debris collected at base of Tamarix L. sp.; MNHN GoogleMaps • 1 ♂; Melilla [located on the northern coast of Morocco]; 35°18′04″ N, 2°56′13″ W; May 1951; F. Codina coll.; MNHN GoogleMaps • 1 ♀; Melilla; 35°18′04″ N, 2°56′13″ W; Dec. 1951; Prado Alcaide coll.; MNHN. GoogleMaps

UNITED STATES OF AMERICA • 1 ♂; California, Roseville; 38°45′41.3″ N, 121°17′22.2″ W; 31 Aug. 2020; G. Forister coll.; (https://bugguide.net/). GoogleMaps

Redescription ( ♂)

MEASUREMENTS. Body length 3.0– 3.5 mm.

COLOR. Body integument uniformly pale brown, apex of rostrum slightly darker; elytra and pronotum with minute recumbent whitish setae, glabrous in appearance.

HEAD. Rostrum slightly longer than pronotum in lateral view (1.1 ×), regularly and moderately downcurved; in dorsal view 4.5–5× as long as wide, integument densely punctate, forming 5 longitudinal carinae; base of rostrum slightly constricted laterally; antennae inserted near apical ¼ of length in lateral view; head capsule densely punctate in dorsal view, forehead flat; eyes convex, exceeding lateral curve of head capsule in dorsal view; antennal funicle with first segment 2.8× as long as wide, slightly longer than segments 2–3 together, 2 about 2× as long as wide, 3–7 transverse.

PRONOTUM. Wider than long (W: L ratio: 1.50–1.63), widest at base, 0.95 × as wide there as elytra at humeral angles, sides slightly convex, converging regularly from base to apex; apical constriction distinct, about as deep as width of scape at base; integument dull, punctures superficial, hardly visible among granules.

METATHORAX. Metanepisterna with recumbent white setae, non-contiguous.

ELYTRA. Longer than wide (W: L ratio: 0.85); sides strongly convex, widest beyond middle of length; humeri raised; apex jointly rounded or notched at level of suture; striae with punctures about ¼–1/5 as wide as width of interstriae; interstriae flat, interstriae 5 raised, more so between basal and apical 1/6 of length, 9 flat, enlarged and merged with 10th at base; scutellar shield rounded, coated with few small recumbent scales, not concealing integument.

ABDOMEN. Underside with ventrites uniformly pale brown, with overlapping whitish setae, usually longer in middle of each ventrite. Stridulatory plate with lines of 8 granules ½ × as long as median line, slightly convex. Central sclerotized area longer than wide, rounded at base ( Fig. 25F View Fig ).

LEGS. Profemora moderately thickened near middle of length; protibiae with external margin straight, internal slightly bisinuate, bearing a comb of setae on apical ¾ of length, setae about as long as 4 th tarsomere; claws simple.

TERMINALIA. Body of penis elongate (W: L ratio: 0.27), about 1.5 × as long as apodemes; sides slightly convex in dorsal view, widening from base to apical ⅓, from there converging apicad, converging abruptly in apical 1/6, apex rounded; in lateral view curvature stronger in basal 2/5 of length, width narrowing regularly from near ½ of length, apex acute, straight ( Fig. 25E View Fig ).

Sexual dimorphism

Females can be distinguished from males by the rostrum which is more shiny and distinctly narrowed near base. In lateral view, rostrum is distinctly longer (1.25×) than pronotum in females (1.1 × in males; Fig. 25C–D View Fig ). The antennae are inserted near the apical ⅓ in females (¼ in males).

Life history

This species is the specific brood-site pollinator of Phoenix canariensis ( Arecaceae ), the Canary Island date palm. Adults visit male inflorescences at anthesis stage. Development of larvae and pupae takes place in the enclosed flowers. The development continues on the ground after flower abscission, the declining flower forming a cell protecting the pupa. Each flower hosts only one larva ( Piry & Gompel 2002). In this pollination by deceit system, adults carrying pollen and searching for male inflorescences are inadvertently attracted by female inflorescences (producing similar olfactory clues) where they transfer pollen to stigma ( Meekijjaroenroj & Anstett 2003). Derelomus piriformis was also recorded on male inflorescences of Chamaerops humilis in the South of France ( Veyret 1940, identified as D. subcostatus in the latter paper), but there is no evidence that it can use this palm for larval development. Adult specimens may be found active on its hosts as long as male inflorescences in anthesis are available. This flowering phenology seems to vary across areas of introduction, from late summer to late autumn in the south of France ( Piry & Gompel 2002), all year round in Israel ( Friedman 2006). Adults are attracted by UV lights ( Piry & Gompel 2002).

Distribution

This species is native to the Canary Island where Phoenix canariensis originates. This palm is widely traded and planted for ornamental purposes, and D. piriformis has probably been transported simultaneously. It is now widely distributed in the Mediterranean region and Madeira Island (sorted by date of first record): Morocco, 1930 ( Hoffmann, 1938); Madeira ( Portugal) & France, 1936 ( Hoffmann 1938; Veyret, 1940; PW collection); Italy, 1966 (CBGP coll.; Abbazzi & Osella 1992); Israel, 1976 ( Friedman 2006); Greece, 1990 ( Kakiopoulos et al. 2022); Corsica Island ( France), 2015 (CBGP coll.). Further records: Canary Islands and Spanish mainland (Caladara 2013). Introduced to South America ( Chile) with its host plant ( Elgueta & Marvaldi 2006) and to North America (California).

Remarks

In A. Hoffmann’s collection housed at MNHN, three specimens corresponding in all aspects to the material listed in the original description of D. piriformis and bearing a red type label were located. As no specific specimen was designed in the type series, a specimen (Funchal, Madeira) was designated as the lectotype for this species [here designated] and was relabelled accordingly. The two other specimens from the series (Rabat, Morocco) were labelled as paralectotypes. Due to the uncommon sexual dimorphism in this species (males have the elytra more convex than females, a condition rare in weevils), the specimens considered by A. Hoffmann as males are in reality females, and conversely ( Piry & Gompel 2002). The sex of specimens reported above corresponds to verified specimens, based on dissection when necessary. In the same collection, a female specimen labelled “ Derelomus kocheri ” by the hand of Hoffmann and bearing a red type label was located. For the reasons described above, this specimen is not a male as reported in the original description but a female one. This specimen is the holotype of Derelomus kocheri Hoffmann, 1957 and was labelled accordingly. Detailed examination of external and internal morphological features of this specimen and comparison with type and non-type material of D. piriformis from various regions revealed no relevant differences. In addition, the type locality of D. kocheri (Rabat, Morocco) is the same as the paralectotype of D. piriformis . As a result of this, the species name Derelomus kocheri Hoffmann, 1957 is proposed as a junior synonym of Derelomus piriformis ( Hoffmann, 1938) [new synonymy].

Due to the early introduction of D. piriformis around the Mediterranean Sea and to the unclear taxonomic definition of D. subcostatus Boheman, 1844 (= D. chamaeropis ( Fabricius, 1798) , see Remarks section under that species), many specimens referred to as D. subcostatus in early collections and publications correspond to D. piriformis in reality. This is relevant to the publication of Veyret (1940).