Elaphidion antiguensis, Vlasak, 2019

Vlasak, Josef, 2019, A new species of Elaphidion Audinet-Serville, 1834, from Antigua and comparison with E. excelsum Gahan, 1895, from Guadeloupe (Coleoptera: Cerambycidae: Elaphidiini), Zootaxa 4688 (3), pp. 442-446 : 442-446

Elaphidion antiguensis sp. nov.

( Figs. 1–2 )

Diagnosis. Large species, similar in appearance to E. excelsum from which it can be distinguished by the following characteristics: patches of pubescence more dispersed across elytral disc (mostly restricted to along suture in E. excelsum ), triangular patches of pubescence on vertex absent (well defined in E. excelsum ); elytral apices dentate (bispinose in E. excelsum ), sutural angle surpassing lateral angle (reversed in E. excelsum ), outer spine on antennomeres III–V straight (arcuate, pointing outward in E. excelsum ), meso- and metafemoral apices dentate, lacking short, acute spines present in E. excelsum ; tegument reddish-brown (dark brown in E. excelsum ).

Description. Male ( Figs. 1–2 ). Large, elongate, subparallel. Integument shining, reddish-brown, humeri with dense patches of tawny, appressed pubescence, less dense pubescence along suture, epipleural margin, and in small patches throughout elytra, fewer laterally.

Head. Frons coarsely irregularly punctate, with golden setae not obscuring integument. Dense golden pubescence around eyes (except posteriorly) and around fronto-clypeal margin. Eyes large, emarginate. Interantennal impression weak, antennal tubercles not strongly elevated. Area between antennal tubercles coarsely, irregularly punctate with sparse setae, vertex glabrous with sparse punctures and setae. Antennae short, reaching ventrite IV, apex of antennomere IV reaching elytral base. Antennomere III subequal to scape, with narrow brush of golden setae medioventrally, antennomeres IV–X gradually decreasing in length, antennomere XI distinctly longer than preceding segment. Scape coarsely punctate, gradually expanded from base to apex, antennomeres III–VI weakly bispinose apically, spine size gradually decreasing, antennomeres IV–VII weakly carinate, antennomere XI arcuate.

Thorax. Pronotum inflated, distinctly broader than long, arcuate laterally, only slightly narrower than elytral base, with shallow, broad impressions, more pronounced on sides. Basal constriction slightly more developed. Densely, finely, confluently punctate, covered with short, tawny appressed pubescence, mostly not obscuring integument. Glabrous medial longitudinal callus, narrowed in apical third, glabrous lateral calli in form of numeral “7”, small lateral glabrous area on each side. Prosternum densely, finely, confluently punctate with short appressed pubescence. Prosternal process acutely declivous, weakly expanded at apex, densely, finely, confluently punctate in middle, glabrous areas on sides expanding towards apex. Mesosternal notch developed. Elytra. With moderately dense, large punctures, each with distinct seta; dense patch of appressed setae covering humeri; less dense pubescence along epipleural margin and suture; small, irregular patches of pubescence on elytral disc, gradually fewer laterally. Apices bidentate, sutural angle more strongly produced, nearly spiniform. Scutellum. Densely clothed with tawny appressed pubescence. Legs. Short, hind femora reaching middle of ventrite III, with sparse, tawny pubescence. Meso- and metafemoral apices dentiform.

Abdomen. With tawny, sparse, appressed pubescence, denser on sides. Ventrite V truncate at apex.

Female ( Figs. 3–4 ). Differs from male by having shorter antennae (reaching base of ventrite II), antennomere XI subequal to antennomere X and not curved; narrower pronotum with denser pubescence, mostly obscuring integument, pronotal calli more developed, pronotum less inflated and more gibbose on sides; prosternum glabrous with sparse large and small punctures, covered with sparse long pubescence. Ventrite V narrower and rounded at apex.

Dimensions in mm (holotype male/ paratypes (8 males and 8 females )). Total length, 32.5/26.2–33.9; elytral length, 22.8/18.4–24.4; humeral width, 8.6/6.6–9.3; pronotal length, 6.5/4.8–6.6; pronotal width, 8.1/5.8–8.5.

Type Material. Holotype male: Antigua, 1 km east of Darkwood Beach , Jul 2018, J. Vlasak col., in Haematoxylon campechianum ( CMNH) ; 16 paratypes (8 males and 8 females), Antigua, 7 from: same locality as holotype, 8 from: English Harbour, 1 from: trail from Rendezvous Bay Beach to Wallings Reservoir, all July 2018, J. Vlasak col. ( CMNH, JVC, and WIBF).

Etymology. The name refers to the type locality.

Biology. The biology of E. antiguensis ( Figs. 5–6 ) is similar to that of E. excelsum ( Figs. 7–8 ). Both species develop in a living host, which is relatively uncommon for the genus, whose members typically utilize recently dead woody plants for development. The larva excavates a large, up to 1 m long tunnel that is kept empty by expelling large quantities of fine, granular frass. The frass can be seen in large piles, often several centimeters tall, on the ground ( Fig. 6 ). In the case of E. excelsum , the fine frass floats around the infested roots ( Chalumeau & Touroult 2005). The pile of frass is quite conspicuous and it greatly facilitates finding trees with larvae. The mature larva prepares the emergence hole either entirely through the bark or leaves only a paper-thin layer of intact bark ( Fig. 5 ). The tunnel is sealed with a wad of fibrous frass.

Although E. excelsum is apparently restricted to one host species ( Rhizophora mangle ), E. antiguensis was found in three rather different species of woody plants. Larval workings were seen frequently in a mid-size tree Haematoxylon campechianum L. ( Fabaceae ) ( Fig. 5 ) and a small shrub Picramnia pentandra Sw. (Picramniaceae) ( Fig. 6 ). Less frequently, the workings were also seen in a vine Senegalia westiana (DC.) Britton & Rose ( Fabaceae ). All host plants were found in xeric areas on the island, which is in contrast to the mangrove swamps that are home to E. excelsum .

Figures

FIGURES 1–2. Elaphidion antiguensis, holotype male. 1, Dorsal view; 2, Ventral view.

FIGURES 3–4. Elaphidion antiguensis, paratype female. 3, Dorsal view; 4, Ventral view.

FIGURES 5–8. Larval habits of E. antiguensis (5–6) and E. excelsum (7–8). 5, Haematoxylon campechianum with a pile of frass (arrow), exposed long empty tunnel (arrow) and an old emergence hole (arrow), inset: prepared emergence hole cut all the way through bark or with a thin layer of bark left intact. The fibrous frass sealing the tunnel is apparent; 6, Picramnia pentandra with a conspicuous pile of granular frass around its base; 7, Root of Rhizophora mangle with an inconspicuous future emergence hole of E. excelsum (enlarged in inset), at Plage Du Souffleur, Grande-Terre, Guadeloupe; 8, The same root after chopping off a layer of wood. The long tunnel with a pupal cell and a pupa can be seen (inset: future emergence hole from Fig. 7 inset after removal of bark).