Derelomus chamaeropis ( Fabricius, 1798 )

Derelomus chamaeropis ( Fabricius, 1798)

Fig. 24 View Fig

Curculio chamaeropis Fabricius, 1798: 167 .

Ochrinulus antigae Reitter, 1887: 18 .

Derelomus subcostatus Boheman, 1844: 92 . Syn. nov.

Derelomus chamaeropis – Schoenherr 1825 (systematics). — Lepesme 1947 (key). — Veyret 1940 (biology).

Derelomus chamaeropis var. Β – Gyllenhal 1836.

Derelomus chamaeropsis [misspelling] – Anstett 1999. — Dufaÿ et al. 2002. — Dufaÿ & Anstett 2004 (life history). — Haran et al. 2022a (phylogenetic relationships).

Diagnosis

This species can be distinguished from others of the D. ephippiger group by the combination of the pronotum almost as wide as the elytra near the middle of the length and the elytra comparatively elongate (W: L ratio: 0.68–0.77), lacking a contrasting dark pattern and with interstriae 9 flat in females, not enlarged in males. This species is closely related and sometimes sympatric with D. piriformis , but in the latter species, males have very convex elytra and a comb of setae on the protibiae (side of elytra only slightly convex and protibiae lacking comb in D. chamaeropis ) and the females have a longer and narrower rostrum ( Fig. 25B–D View Fig ). Uncorrected p -distances between these species range from 8.0 to 8.8%. GenBank accession numbers for the corresponding DNA barcodes: OK188812 View Materials –13/PV698448–49–51– 54–55–57–60–61–63–68–73/ (not an exhaustive list).

Material examined

Holotypes

MOROCCO • ♀; “ Tanger.; Schousboe. [ Peder K. A. Schousboe, Danish diplomat and botanist based in Morocco]; Mus: S: & T.L: [collection Sehestedt & Tonder Lund; former Copenhagen collection of Fabricius types]” “TYPE” “ ZMUC00037405 ” “Holotype ♀; Curculio ; chamaeropis ; Fabr. 1798; des. J. Haran 2025” “ Derelomus ; chamaeropis ; (Fabr. 1798); J. Haran 2025”; ZMK.

COUNTRY (?) • ♀; “ Barbaria [ Northern coast of Africa, from Morocco to Lybia ]; Mus: T: Lund. [collection Sehestedt & Tonder Lund; former Copenhagen collection of Fabricius types]” “TYPUS [red label]” “Holotype ♀; Derelomus ; chamaeropis ; var. β (beta); Gyllenhal 1836 [G. Kuschel’s label]” “ Derelomus ; chamaeropis ; (Fabr. 1798); Kuschel 2005 [G. Kuschel’s label]” “Naturhistorika; Riksmuseet; Stockholm; NHRS .

ITALY • ♂; “Ménétr. [Edouard Ménétries, french entomologist at St. Petersburg Academy of Science]” “Géné.; Sardinia [Carlo Giuseppe Gené, italian entomologist at the Royal Zoological Museum, Turin]” “TYPUS [red label]” “647” “ Derelomus ; chamaeropis ; Sardinia; Mannerheim. [Carl Gustaf Mannerheim, finish governor and entomologist]” “Holotype ♂; Derelomus ; subcostatus ; Boheman, 1844; Haran des. 2025” “ Derelomus ; chamaeropis ; (Fabr. 1789); Haran des. 2025” “Naturhistorika; Riksmuseet; Stockholm”; NHRS.

Other material

ALGERIA • 2 ♀♀; Souk Tlata, “ Dradek ”; 35°03′43″ N, 2°00′00″ E; collector and date unknown; CBGP GoogleMaps • 4 ♂♂, 6 ♀♀; Algiers; 36°48′11″ N, 3°00′32″ E; collector and date unknown; NHRS GoogleMaps • 1 ♂; Mascara; 35°23′39″ N, 0°09′39″ E; H. Lucas coll.; MNHN GoogleMaps • 1 ♂; Oran; 35°41′52.8″ N 0°40′08.4″ W; 1906; C.H. Coquerel coll.; MNHN GoogleMaps • 1 ♂; Oran; 35°41′53″ N, 0°40′08″ W; G. Allard coll.; MNHN GoogleMaps • 1 ♂; [locality?]; NMB • 1 ♀; [locality?]; NHMUK • 1 ♀; no precise locality; 1905; Sharp coll.; NHMUK • 1 ♀; Misserghin; 5°36′54″ N, 0°44′46″ W; NHMUK. GoogleMaps

FRANCE • 1 ♂; Banyuls sur Mer; 42°28′23″ N, 3°06′57″ E; 28 Mar. 2013; C. Chauvelier coll.; JHAR07412 ; CBGP GoogleMaps • 1 ♂; Palavas les Flots; 43°31′34″ N, 3°55′54″ E; 15 Apr. 2022; J. Haran coll.; inflorescences of ornemental Chamaerops humilis ; JHAR04762 ; CBGP GoogleMaps • 1 ♂; Montpellier, Jardin des plantes ; 10 May 1997; 43°36′50″ N, 3°52′20″ E; S. Piry coll.; Chamaerops humilis ; SPc.6031; CBGP GoogleMaps • 4 ♂♂, 1 ♀; Toulon, jardin d’acclimatation ; 43°31′45″ N, 6°56′18″ E; May 1928; De Boissy coll.; male flowers of Chamaerops ; MNHN GoogleMaps • 6 ♂♂, 8 ♀♀; Alpes Maritimes, Mandelieu; 43°31′52″ N, 6°56′14″ E; May 1940; on Chamaerops humilis ; MNHN GoogleMaps • 1 ♂, 3 ♀♀; Var, la Garde ; 43°07′38″ N, 6°01′26″ E; 11 May 1929; P. Veyret coll.; PW GoogleMaps • 1 ♂, 3 ♀♀; Var, la Garde ; 43°07′38″ N, 6°01′26″ E; May 1932; P. Veyret coll.; PW GoogleMaps • 1 ♀; Corse, Ile-Rousse; 42°37′56″ N, 8°56′21″ E; 6 Apr. 2016; J. Haran coll.; male inflorescence of C. humilis ; JHAR02984 ; CBGP GoogleMaps • 10 specs (preserved in ethanol); Sète; 43°24′29″ N, 3°42′11″ E; 18 May 2024; J. Haran coll.; larvae in rachis of male inflorescence of C. humilis ; JHAR07980 ; CBGP. GoogleMaps

ITALY • 3 ♂♂, 4 ♀♀, 8 specs (preserved in ethanol); Sicily, Palermo; 38°11′35″ N, 13°16′38″ E; 2022; M. Hossaert coll.; male inflorescence of C. humilis ; JHAR04886 ; CBGP GoogleMaps • 1 ♂; Sicily [no precise locality]; 37°17′46″ N, 14°09′54″ E 1847; L. Benoit coll.; MNHN GoogleMaps • 1 ♂; Sicily [no precise locality]; 37°17′46″ N, 14°09′54″ E; Sharp coll.; NHMUK GoogleMaps • 1 ♂, 3 ♀♀, 11 specs (preserved in ethanol); Sicily, Borgo Casellazzo; 38°02′46″ N, 12°51′30″ E; 11 Apr. 2024; M. Dufaÿ coll.; male inflorescence of C. humilis ; JHAR08306 ; CBGP GoogleMaps • 50 specs (preserved in ethanol); Sicily, Cornino; 38°05′54″ N, 12°39′40″ E; 14– 16 Apr. 2024; M. Dufaÿ coll.; male inflorescence of C. humilis ; JHAR08307 ; CBGP GoogleMaps • 1 ♀, 1 spec. (preserved in ethanol); Pantelleria Island; 36°46′30″ N, 11°57′51″ E; 22 Apr. 2023; T. Auffray coll.; male inflorescence of C. humilis ; JHAR05699 ; CBGP GoogleMaps • 1 ♂, 3 ♀♀; Genova, Pegli ; 44°25′30″ N, 8°48′36″ E; 15 May [year?]; S. Solari coll.; NHMUK GoogleMaps • 1 ♂, 1 ♀; Genova, Pegli ; 44°25′30″ N, 8°48′36″ E; 5 May 1915; S. Solari coll.; NHMUK GoogleMaps • 2 ♂♂, 1 ♀; Gallipoli; 40°03′14″ N, 17°59′24″ E; 1905; Sharp coll.; NHMUK GoogleMaps • 3 ♂♂, 2 ♀♀, 10 specs (preserved in ethanol); Bari; 41°07′45″ N, 16°51′58″ E; 27 Apr. 2024; J. Haran coll.; male inflorescence of C. humilis ; JHAR07851 ; CBGP. GoogleMaps

MOROCCO • 1 ♀; Larache; 35°10′16″ N, 6°10′05″ W; 1885; De La Roche coll.; 265; MNHN GoogleMaps • 1 ♂, 3 ♀♀; South Asni; 31°12′51″ N, 7°58′01″ W; 18 May 2007; J. Pelletier coll.; “friche” [wasteland] Chamaerops ; JHAR07413 ; CBGP GoogleMaps • 1 ♀; Haut Atlas, 18 km S of Demnat; 31°35′46″ N, 6°59′52″ W; 1600 m a.s.l.; 21 May 2007; J. Pelletier coll.; JHAR07414 ; CBGP GoogleMaps • 4 ♂♂, 4 ♀♀; Mgoun, Azizal; 31°27′36″ N, 6°33′00″ W; 21 May 2007; J. Pelletier coll.; JHAR07415 ; CBGP GoogleMaps • 1 ♂; Khénifra, Azrou; 33°25′55″ N, 5°11′29″ W; A. Thery coll.; CBGP GoogleMaps • 1 ♂; Korifla [?]; A. Thery coll.; CBGP • 4 ♂♂, 2 ♀; Tanger area ; 35°47′39″ N, 5°51′21″ W; 1857; Favier coll.; MNHN GoogleMaps • 1 ♂, 2 ♀♀; Tangier; 35°47′39″ N, 5°51′21″ W; 1915; NHMUK GoogleMaps • 2 ♂♂, 2 ♀♀; Tangier; 35°47′39″ N, 5°51′21″ W; Sharp coll.; NHMUK GoogleMaps • 1 ♂; Tangier; 35°47′39″ N, 5°51′21″ W; Schill coll.; NHMUK GoogleMaps • 1 ♂, 3 ♀♀; Tangier; 35°47′39″ N, 5°51′21″ W; J.J. Walker coll.; NHMUK GoogleMaps • 2 ♂♂, 1 ♀; Khénifra; 32°57′00″ N, 5°40′38″ W; 19 Apr. 2006; J. Pelletier coll.; male inflorescence of C. humilis ; JHAR03220 ; CBGP GoogleMaps • 1 ♀; no precise locality; 1905; Sharp coll.; NHMUK • 1 spec. (sex undetermined); S of Berkane, N of Aïn-es-Sfa, Beni Snassen Mts ; 34°49′52″ N, 2°08′46″ W; 13 May 2011; P. Stuben coll.; beating Chamaerops humilis ; (identification by genetic assignation, GenBank acc. KC783895 View Materials ); ZFMK GoogleMaps • 1 ♂, 1 ♀; Ras Foughal [ Jbel Foughal ]; 34°49′59″ N, 2°12′00″ W; 20 May 1932; Vidal coll.; NHMUK GoogleMaps • 1 ♂; Maâmora Forest ; 34°08′53″ N, 6°36′07″ W; Theory coll.; NMB. GoogleMaps

PORTUGAL • 2 ♂♂, 3 ♀♀; Serra de Espinnaço do cao ; 37°16′55″ N, 8°44′00″ W; 8 Jun. 1989; J. Pelletier coll.; 300 m a.s.l.; RB GoogleMaps • 1 ♀; Lisboa; 38°41′53″ N, 9°13′23″ W; Flach. coll.; NHMUK GoogleMaps • 1 ♂; Madeira; Ribeiro Frio; 32°43′56″ N, 16°53′10″ W; Balachowsky coll.; MNHN. GoogleMaps

SPAIN • 4 ♂♂, 1 ♀; Cabo de Palos ; 37°37′09″ N, 0°42′51″ W; 2 Mar. 2001; J. Pelletier coll.; male inflorescence of C. humilis ; JHAR04643 ; CBGP GoogleMaps • 5 ♂♂, 3 ♀♀, 20 specs (preserved in ethanol); Garraf; 41°15′26″ N, 1°54′29″ E; 20 Apr. 2022; M. Dufaÿ coll.; male inflorescence of C. humilis ; JHAR04764 ; CBGP GoogleMaps • 3 ♂♂, 1 ♀; same locality as for preceding; 11 Apr. 1998; S. Piry coll.; Chamaerops humilis ; SPc.6535-36/66-67; CBGP GoogleMaps • 3 ♂♂, 1 ♀; Barcelona; 41°21′32″ N, 2°09′43″ E; 17 Apr. 2013; M. Dufaÿ coll.; male inflorescence of C. humilis ; JHAR04784 ; CBGP GoogleMaps • 1 ♀; Barcelona; 41°21′32″ N, 2°09′43″ E; Odier coll.; NHMUK GoogleMaps • 2 ♂♂; Valencia; 39°25′09″ N, 0°20′13″ W; 17 Apr. 2022; M. Dufaÿ coll.; male inflorescence of C. humilis ; JHAR04786 ; CBGP GoogleMaps • 2 ♀♀; Andalusia, Motril; 36°44′24″ N, 3°31′45″ W; 11 Apr. 1971; J. Péricart coll.; RB GoogleMaps • 1 spec. (sex undetermined); Malaga, NW of Otivar , Sierra del Chapparal ; 36°49′30″ N, 3°42′29″ W; 8 May 2013; P. Stüben and A. Schütte coll.; Quercus ilex L. sieving; ZFMK (identification by genetic assignation, GenBank acc. MK891322 View Materials ) GoogleMaps • 1 ♂; Mallorca Island, Alcúdia ; 39°51′07″ N, 3°07′38″ E; 13 Apr. 1964; W. Leibmann coll.; NHMUK GoogleMaps • 1 ♀; same locality as for preceding; 4 May 2000; R. Rober coll.; NHMUK. GoogleMaps

UNITED KINGDOM • 1 ♂, 2 ♀♀; Gibraltar; 36°07′55″ N, 5°21′03″ W; NHMUK GoogleMaps • 13 ♂♂, 23 ♀♀; Gibraltar; 36°07′55″ N, 5°21′03″ W; J.J. Walker coll.; NHMUK. GoogleMaps

Redescription ( ♂)

MEASUREMENTS. Body length 2.5–3.7 mm.

COLOR. Body integument pale brown, scutellar shield, pronotum and head including rostrum generally darker, in some individuals interstriae 1, sometimes 2 darker as well; elytra and pronotum with minute recumbent whitish setae, glabrous in appearance.

HEAD. Rostrum slightly longer than pronotum in lateral view (1.1–1.15×), regularly downcurved; in dorsal view 4 to 5.5× as long as wide, integument densely punctate, forming 5 longitudinal carinae; antennae inserted near apical ¼ of length in lateral view; head capsule densely and coarsely punctate in dorsal view, forehead flat or slightly concave; eyes convex, exceeding lateral curve of head capsule in dorsal view; antennal funicle with first segment 2–2.2 × as long as wide, slightly longer than segments 2–3 together, 2 longer than wide, 3–7 transverse.

PRONOTUM. Wider than long (W: L ratio: 1.34–1.45), widest at basal ⅓ of length, 0.95–1 × as wide there as elytra at humeral angles, sides slightly convex, converging regularly from basal ⅓ to apex, lateral carina forming notch near middle of length; apical constriction distinct, about as deep as width of scape in middle of length; integument with punctures rounded, space between punctures dull, micropunctate, wider or narrower than diameter of punctures in middle, narrower anteriorly and laterally.

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

ELYTRA. Longer than wide (W: L ratio: 0.68–0.77); sides slightly convex, widest near middle of length; humeri raised; apex jointly rounded or notched at level of suture; striae with punctures about ⅓–¼ as wide as width of interstriae; interstriae slightly convex, interstriae 5 sometimes raised in basal ⅔, 9 flat; scutellar shield rounded, coated with few small recumbent scales, not concealing integument.

ABDOMEN. Underside with ventrites 1–2 darker than 3–5, with minute recumbent whitish setae, not contiguous. Stridulatory plate with lines of 10–11 granules ⅔ × as long as median line, slightly convex. Central sclerotized area longer than wide, truncate at base ( Fig. 24F View Fig ).

LEGS. Profemora moderately thickened near middle of length; protibiae with external margin straight, internal slightly bisinuate, setae on apical half of internal margin recumbent, at most as long as claws; claws simple.

TERMINALIA. Body of penis elongate (W:L ratio: 0.25), about 1.3 × as long as apodemes; sides subparallel in dorsal view, widest in basal ⅔, converging apicad from apical ⅓, apex acuminate; in lateral view curvature stronger in basal ⅓ of length, width narrowing regularly from near ½ of length, apex slightly curved upward ( Fig. 24E View Fig ).

Sexual dimorphism

Females can be distinguished from males by the rostrum which is narrower and longer in dorsal view. In lateral view, the rostrum is distinctly longer than the pronotum in females (slightly longer than pronotum in males; Fig. 24B–D View Fig ). The antennae are inserted at apical ⅓ in females (¼ in males).

Variation

This species is quite polymorphic. Morphological variation occurs at two levels. First, D. chamaeropis consists of genetically isolated lineages distributed around the western part of the Mediterranean region (see Remarks section below). These populations show slight morphological divergences. For example, the rostrum of males is on average slightly longer and narrower in populations from Spain (mean W: L ratio: 0.24 (0.21 – 0.25); width measured at antennal insertion) than those from Sicily (mean W: L ratio: 0.18 (0.15 – 0.22)). Within the eastern clade, rostrum length and width also vary slightly between the French, Italian and Moroccan specimens examined. In addition to these geographic variations, the phenotype of adults in a given population is also variable. Variation includes ‘major’ males, with a comparatively wide pronotum and 5 th elytral interstriae raised and ‘minor’ males with a comparatively narrow pronotum and 5 th elytral interstriae flat. Color variation ranges from specimens uniformly pale brown, to specimens with brown elytra and a dark brown pronotum, head and rostrum ( Fig. 24A–D View Fig ), more rarely with the body (head, pronotum and elytra) uniformly dark brown.

Life history

Derelomus chamaeropis is the specific brood-site pollinator of the Mediterranean dwarf palm: Chamaerops humilis ( Arecaceae ; Anstett 1999). Adults fly and reach inflorescences of both male and female plants, attracted by scents emitted by leaves ( Dufaÿ et al. 2002), thus transferring pollen to the stigma of female inflorescences. They mate and oviposit in the rachis of the inflorescences ( Anstett 1999; Fig. 24I–K View Fig ) and larvae develop in the stem of inflorescences, mainly on male plants. Successful larval development has also been described in female plants, but with markedly lower frequency and densities than on male plants ( Dufaÿ & Anstett 2004; Jácome-Flores et al. 2018). Adults are active during the flowering season of C. humilis , from March to June. Larval development takes place in the decaying woody tissues of rachises from early summer to late winter. Pupation takes place within the rachises. As for many brood-site pollination systems involving weevils, C. humilis is co-pollinated by the sap beetle Meligethinus pallidulus (Erichson, 1843) also developing on male inflorescences (JH obs.) and visiting females ones (M. Dufaÿ pers. com.). Both species are efficient pollinators, even for isolated populations of palms resprouting after fire ( García et al. 2018). The report of D. chamaeropis on P. canariensis (Lepseme 1941) is likely accidental.

Distribution

Coastal regions of the Western Mediterranean area: Algeria, Croatia, France, Italy, Morocco, Spain, including islands ( Corsica, Sardinia, Sicily, Malta; Caldara 2013).

Remarks

In Fabricius’ collection housed at ZMK, a unique female specimen under the identification name “ Curculio (= Rhynchaenus ) chamaeropsis F., 1798” and fitted with a red type label was located. This specimen is the holotype of Curculio chamaeropis Fabricius, 1798 and was labelled accordingly. In Shoenherr’s collection, housed at NHRS, the holotype of Derelomus chamaeropis var. β Gyllenhal, 1836 was located and labelled accordingly. In the same collection, a male specimen bearing a red type label and corresponding in all aspects to the description of Derelomus subcostatus Boheman, 1844 was located. This specimen is the holotype of Derelomus subcostatus Fåhraeus, 1844 and was labelled accordingly. Based on a detailed examination of these types and a molecular analysis of specimens newly sampled in the region of the type localities, it is stated here that the specimens used to describe Derelomus chamaeropis var. α and β and D. subcostatus all belong to the same species. As a result, the names Derelomus subcostatus Fåhraeus, 1844 and Derelomus chamaeropis var. β Gyllenhal, 1836 are proposed as junior synonyms [new synonymy] of Derelomus chamaeropis ( Fabricius, 1798) . The elements used to reach this conclusion are detailed hereafter.

Derelomus chamaeropis was described on a female from N Morocco. This species is specific to Chamaerops humilis (see Life history section below) and follows the distribution range of this palm in the western Mediterranean region ( Caldara et al. 2013). Derelomus subcostatus was described from a male specimen from Sardinia Island ( Italy), the specimens related to this species being also associated with C. humilis ( Veyret 1940) . The limited details in the original descriptions and the substantial intraspecific variation found in D. chamaeropis have resulted in confusions in the interpretation of both species. For some authors, D. subcostatus is a valid species occurring in sympatry with D. chamaeropis ( Tempère & Péricart 1989; Caldara et al. 2013) while others treat it as a morphological variant of D. chamaeropis ( Hoffmann 1958) . In order to clarify this situation, fourteen populations (1– 4 specimens per population) were sampled across the distribution range of C. humilis ( France, mainland and Corsica Island; Italy, Sicily and Pantelleria Island; Morocco and Spain; see detail in Other material section) and sequenced for the standard barcode fragment (see Material and methods section for protocol). This sampling included specimens identified by direct comparison with the holotypes: a female specimen of D. chamaeropis from Morocco (JHAR03220-02) and a male specimen of D. subcostatus from Italy ( Sicily; JHAR04886-08). The populations from Spain also included specimens related to the varieties α and β of D. chamaeropis (male with or without costate elytra, with or without dark head and pronotum; Fig. 24A–C View Fig ). Derelomus chamaeropis was recovered as a single species for all the species delimitation methods used ( Fig. 34 View Fig ), despite intraspecific distances ranking up to 3.4% between specimens from Morocco ( KC783895 View Materials ) and Spain (JHAR07851-02). Also, the variations observed at population level in the male are not associated with genetic divergences in mitochondrial sequences ( Fig. 33 View Fig ). As such, all specimens previously referred to as D. chamaeropis and D. subcostatus are in fact a unique species forming a ring of more or less isolated populations distributed in the western mediterranean area. This phylogeographic pattern is typical of Mediterranean species and results from the isolation of populations in southern European refugia during glacial maxima (Hewitt 2000). This pattern is also in agreement to some extent with the genetic structure of Chamaerops humilis that shows substantial differentiation among populations across its distribution range ( De Cauwer et al. 2025). This may suggest that both this palm and its associated pollinator experienced similar fragmentation of distribution range during glacial maxima. At population level, specimens show substantial morphological variation, in particular in males, a condition widely encountered in weevils engaged in brood-site pollination ( Haran et al. 2020, 2023a) and not associated with genetic divergence.

The Sardinian specimen used by Boheman to describe Derelomus subcostatus combines the two factors of morphological variability in D. chamaeropis : it is slightly morphologically divergent from populations from Morocco used to describe D. chamaeropis (rostrum comparatively short) and exhibits the costate elytra of a ‘major’ male, thus showing a substantial apparent divergence with the female holotype of D. chamaeropis . But as detailed above, all these specimens belong to the same species. The species name Ochrinulus antigae Reitter, 1887 was set in synonymy with Derelomus chamaeropis ( Fabricius 1798) by Reitter himself ( Reitter 1887), the specimen used to describe this species was collected in Barcelona ( Spain) [not verified in the context of this study].