Mascarapion Wanat & Poussereau, 2019

Wanat, Marek & Poussereau, Jacques, 2019, Mascarapion, a new genus of the Apioninae (Coleoptera, Curculionoidea) from the Mascarene Islands, Zootaxa 4615 (2), pp. 343-350 : 344-347

Genus Mascarapion Wanat & Poussereau , n. gen.

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Type species: Apion roudieri Richard, 1957 .

Diagnosis. The new genus belongs to the “Aspidapiitae group” of derived apionine (sub)tribes and it is distinct from all described genera in the following unique combination of characters: scutellar shield elongate and tri-tuberculate, scales on front margin of pronotum adpressed instead of projecting forward (centripetal type of vestiture), first stria abbreviated and approximating elytral suture behind scutellar apex, male tibiae without mucrones and with all basal tarsomeres provided with ventral spine, spiculum gastrale with both fork and rounded expansion, tegminal plate largely expanded latero-ventrally and having minute to indistinct fenestrae.

Description. Body length less than 3 mm (without rostrum), all parts light to dark testaceous. Vestiture distinct, composed of long hair-like or piliform scales, on pronotum and elytra bi- or tri-colored and forming a pattern of light bands and darker flecks, at base of 3 rd elytral interval with spots of condensed scales, on ventral side with dense whitish scales not forming contrasting spots.

Rostrum cylindrical, stout and nearly straight, sexually dimorphic, more than 2.5 × as long as wide and not shorter than pronotum; ventral sulci complete, with punctures and piliform scales, separated by complete narrow median keel; latero-ventral sulci complete and distinct, with scaliferous punctures; scrobes weakly impressed, on head venter with lateral edges and complete median carina ( Fig. 11 ).

Antennae inserted at about basal third of rostrum, thin; setosity inconspicuous, weakly protruding; scape longer than three basal funicular segments combined; funicle with pedicel longer than 2 nd segment, terminal segments small, isodiametric to weakly transverse; club compact, with evident sutures.

Head hemispherical; eyes large and not prominent, with dense circum-ocular scales similar in sexes and not forming evident subocular fringe (Figs 1, 2); epifrons between eyes clearly narrower than rostrum base, flat, finely punctured and not striolate; temples short, less than one-third of eye length, with fine sculpture and scales present only very close to posterior margin of eye.

Pronotum campaniform; vestiture clearly centripetal ( Fig. 9 ), basal flange narrow and with weakly prominent angles, with scales arranged obliquely, not parallel to median axis; scales along front margin adpressed; punctation of pronotal disc fine and superficial; prescutellar fovea missing; pronotal sides without foveae; prosternum twice as long as hypomeron; prosternal process between procoxae depressed, analogous hypomeral process raised, fully united with hypomeron (prosternellum absent).

Scutellar shield long, with two pointed basal tubercles and raised tip.

Elytra oblong, widest slightly behind middle, 1.5–1.6 × as long as wide, convex, without prominent apical part; striae impressed, catenulate-punctate, without edges, septa of punctures narrow and depressed; stria 1 abbreviated at base, approximating suture and tip of scutellum; apical junction of striae typically 1+2+9, stria 10 reduced, outer stria weakly angled at junction with 2; intervals convex, interval 1 narrowed basally; sutural apex with typical api- onine locking device; specialized setae two separate, subapically on 9th interval Mesocoxae separated by ca. 0.2 of their diameter; metaventral process strongly raised; coxal cavities without rim. Metathoracic wings functional, with no trace of radial window; 1A vein as paired rudiments; main 2A vein slightly angled at sub-median spur, which is extended into long, bent a1–a2 rudiment, no other spurs; 3A vestigial; anal notch deep and narrow ( Fig. 18 ). Tarsal claws with low and broad triangular teeth ( Fig. 2) Male. Basal tarsite of all legs with a small ventral spine. Abdominal ventrite 5 broadly rounded, simply convex. Pygidium with only extreme margin exposed, separated by narrow transverse incomplete sulcus ( Figs 12–14 ). Sternite 8 bilobed, without carinae ( Fig. 15 ). Sternite 9 Y-shaped, with a large, rounded expansion associated with the fork ( Figs 24, 25 ). Tegminal plate connate with basal piece, with large lateral lobes enveloping penis ( Figs 22, 23 ); membranous lobes short and broad, microsetose; parameroid lobes transverse, desclerotised internally, without macrochetae; fenestrae small and widely separated or indefinite; prostegium short, shallowly emarginate medially ( Figs 19–22 ). Penis flattened; tectum plate-like, weakly sclerotized; apodemes shorter than pedon, without a bridge; endophallus microspinose, without sclerites, largely enclosed within penis in repose ( Figs 26–29 ).

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FIGURES 1–8. Habitus and rostrum shape: 1–3. Mascarapion roudieri:1) male, lateral view; 2) female head, lateral view; 3) female, dorsal view. 4–7. M. richardi: 4) male, dorsal view; 5) male head, dorsal view; 6) female head, dorsal view; 7) female head, lateral view. 8) M. roudieri, female head, dorsal view.

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Female. Rostrum longer, but of similar shape as in male. Ventrite 5 more narrowly rounded, simply convex. Tergites 7 and 8 broad, evenly sclerotized, without median clearings ( Fig. 30 ). Spiculum ventrale with small, forked sternal plate. Ovipositor short; coxites subtruncate; styli robust, 1.5 × as long as wide, inserted apically to coxites, with apical setae. Spermatheca c-shaped, short, robust, thin-walled and finely wrinkled; entrances of duct and gland not prominent.

Distribution. Réunion Is., Mauritius Is.

Etymology. The name of new genus is derived from the Mascarene Archipelago, the area of its occurrence, and combined with the Greek Apion . Gender neuter.

Biology. No confirmed biological data are known, but at least the species from Réunion I. are most likely associated with malvaceous plants, apparently with trees of the genus Dombeya (fomerly Sterculiaceae , now included in Malvaceae (APG II, 2003)).

Comments. With its metathoracic wing devoid of radial window, elongate and tri-tuberculate scutellum, and concealed male pygidium, the new genus clearly falls into the group once defined by Alonso-Zarazaga (1990) as supertribe Aspidapiitae. However, as with most of Palaeotropical genera of this Aspidapiitae lineage, it is difficult to place Mascarapion unambiguously in any recognized tribe, or rather subtribe in the current system adopted e.g. by Bouchard et al (2011) and Alonso-Zarazaga et al (2017). It shares the structure of male pygidium with Malvapiina , elongate tri-tuberculate scutellar shield with Aspidapiina , centripetal arrangement of pronotal vestiture despite of presence of basal flange again with some Malvapiina and Harpapion Voss , missing male tibial mucrones, structure of tegminal plate and expanded spiculum gastrale with Kalcapiina , while toothed all basal tarsites in male and largely abbreviated sutural stria are unique characters among aspidapiitae tribes. The division of the group currently ranked as Apionini has been proposed for a limited set of only Palaearctic genera, and it does not work properly when non-Palaearctic taxa are considered. The problem is primarily with a distinction between the subtribes Aspidapiina , Malvapiina and Kalcapiina , which was already indicated by Alonso-Zarazaga & Wanat (2014). Problematic monophyly of Aspidapiina and Kalcapiina has been recently corroborated in a comprehensive molecular phylogenetic analysis of Palaearctic apionines by Winter et al. (2016). Considering largely overlapping and mosaic morphological characteristics of Palaeotropical genera of all three subtribes, it seems that their unification into one group of (sub)tribal rank after analyses based on extended taxon sampling is expected.

Figures

FIGURES 9–18. Pronotum and elytral base: 9) Mascarapion roudieri; 10) M. richardi. 11) M. roudieri, female, underside of rostrum, SEM micrograph (scale bar 0.2 mm). 12–14. Male pygidium: 12) M. richardi, dorsal view; 13) same, lateral view; 14) M. roudieri, posterodorsal view. 15) M. richardi, sternite 8. 16–17. M. roudieri, female: 16) ovipositor; 17) spermatheca. 18) M. roudieri, male, metathoracic wing.

FIGURES 19–30. Terminalia: 19–23. Tegmen: 19) M. roudieri, dorsal view; 20) same, lateral view; 21) M. richardi, dorsal view; 22) same, lateral view; 23) same, anterior view. 24, 25. Spiculum gastrale (sternite 9): 24) M. roudieri; 25) M. richardi. 26–29. Penis: 26) M. roudieri, dorsal view; 27) same, lateral view; 28) M. richardi, dorsal view; 29) same, lateral view. 30) M. roudieri, female, tergite 7.