Rhynchitapion, Wanat, 2021

Wanat, Marek, 2021, New basal taxa of South African Apioninae (Coleoptera: Curculionoidea: Brentidae), Zootaxa 5035 (1), pp. 1-60: 6-7

publication ID

https://doi.org/10.11646/zootaxa.5035.1.1

publication LSID

lsid:zoobank.org:pub:95CC79A1-8A2D-4532-8E59-A3DA1A437A62

DOI

http://doi.org/10.5281/zenodo.5499030

persistent identifier

http://treatment.plazi.org/id/A40A5638-E845-CD5F-FF6B-2B6EFF116B45

treatment provided by

Plazi

scientific name

Rhynchitapion
status

gen. n.

Rhynchitapion   gen. n.

Type species: Rhynchitapion variiforme   sp. n.

Diagnosis. Small to medium sized species, body length 1.4–3.7 mm. Head with rostrum base, pronotum, elytra and legs bearing long, erect hair-like setae, on head and pronotum directed obliquely forward; any fully appressed pilosity or scales missing even from the underside of body. Rostrum thin, widest at the thickening basad metarostrum, not less than 2.7 × as long as wide at antennal insertion; antennal pits long-oval; scrobes lateroventral, shallow, vanishing well before head venter. Head markedly transverse. Antennae relatively the longest among Apioninae   , at least 0.8 × as long as elytra and more than twice as long as pronotum; all antennomeres elongate; club loosely segmented, 5–6 × as long as wide. Pronotum in dorsal view trilobate; its disc convex from anterior margin or nearly so, but flattened in basal fifth, punctate, without median fovea and basal flange. Elytral suture apically straight and simple, i.e., without pocket-like lock; basal margin of elytra with low rim vanishing at level of stria 5; five striae present between suture and humeral callus, stria 1 shortened, commencing well behind scutellar shield; both subhumeral and subapical remains of separate stria 10 present; stria 3 apically joining 8. Procoxae pear-shaped, like mesocoxae, with a low, obtuse dentiform process limiting rotation of trochanter ( Fig. 21 View FIGURES 16–27 ); in septum of mesocoxae the mesoventral process is clearly longer than metaventral process. Legs thin, all subequally long. Trochanters elongate, well separating femur and coxa. Femora unarmed, without coarse wrinkles.

In male, all tibiae mucronate; pygidium concealed, lacking anterior apodemes, with well sclerotized internal tongue-like process; membrane between sternites VIII and IX with pair of additional sclerites; endophallus with paired frena, elongate and atypical in shape. Female tergite VII with raised carina along arched apical margin; tergite VIII subdivided.

See also the key to South African genera below.

Description. Body narrow. Integument smooth, at most finely microreticulate, microsculpture net-like, not in form of transverse wrinkles. Coloration variable, black, testaceous or mixed, elytra never with longitudinal stripes. Erect setae dense or sparse, irregularly arched, on head and pronotum all directed anterad, variably long and arising from punctures of variable size; on pronotum setation dual, long and erect on convex anterior part of disc, much shorter and semi-recumbent on flattened basal part.

Rostrum arising from upper half of head in profile, in cross-section flattened in distal part, in dorsal view subparallel-sided, confusedly punctate dorsally and ventrally, lacking regular sulci and rows of punctures; sexual dimorphism in length and shape weak or indiscernible; scrobes vanishing ventrally before thickened rostrum base, their septum broad, not prominent.

Mouthparts of typically apionid type, with 2-segmented maxillary- and 1-segmented labial palps ( Fig. 19 View FIGURES 16–27 ).

Antennae with protruding setae; their insertion on rostrum submedian (0.43–0.55); scape only exceptionally shorter than breadth of mesorostrum, usually distinctly longer, always clearly shorter than combined length of funicular segments 1 and 2, the latter of about the same length; club not less than 5 × as long as wide, with well separated segments, all distinctly elongate.

Head transverse; eyes relatively small and convex, shortly elongate to nearly round; temples punctate and rugose for a short distance behind eye, mostly smooth and finely wrinkled at posterior part of head capsule; subocular setae sparse, protruding; gular area between eyes convex, with minute setiferous punctures, eventual wrinkles transverse, not U-shaped ( Figs. 18 View FIGURES 16–27 , 92 View FIGURES 92–95 ).

Pronotum elongate, with shallow subapical and sub-basal constrictions, in dorsal outline each distant 0.25–0.30 × pronotal length from the respective apical and basal margins, in side view convex except flattened basal part of disc, with rectangular hind corners, lacking basal flange, with fine line along basal margin ( Fig. 17 View FIGURES 16–27 ); the margin behind eyes not thickened, without dense wrinkling; disc and sides irregularly punctate; posterior lateral groove absent; notosternal suture running anterad closely to margin of coxal cavity and not ending in a deeper pit ( Fig. 16 View FIGURES 16–27 ); prosternum at least 2 × shorter than hypomeron, declining posterad; procoxae contiguous, procoxal cavities with low posterior rim; prosternellum fully fused to hypomeron, prominent ( Figs. 21 View FIGURES 16–27 , 94 View FIGURES 92–95 ).

Scutellar shield small, isodiametric, triangular.

Elytra weakly, regularly convex, elongate suboval in dorsal outline, at least 1.65 × as long as wide; basal sutural lock composed of 3–4 oblique elongate laminae and pits ( Fig. 24 View FIGURES 16–27 ); striae shallowly impressed, without sharp edges, punctate, apically joining (1+10)+(2+9), 3+8, whilst striae 4–7 mostly disconnected ( Fig. 16 View FIGURES 16–27 ); on non-black integument strial punctures surrounded by catenulate short-oval chambers visible through integument; intervals smooth, at most with sparse minute punctures; specialized setae not discernible among erect elytral setation.

Wings functional; radial window distinct; cubito-anal vein remnants paired, weakly distinguished, simple; main anal vein (2A in Wanat 2001, AA3+ 4 in Oberprieler et al. 2014) straight to slightly sinuous, without spurs; subsequent 3A vein short, straight; anal notch broad, shallow ( Fig. 31 View FIGURES 28–43 ).

Pterothorax: mesoventrite with anapleural sutures visible or not; mesepimeral sulcus shallow, without clear edges, punctate; intermesocoxal process of mesoventrite long. Mesocoxal cavities with low posterior rim ( Figs. 22 View FIGURES 16–27 , 95 View FIGURES 92–95 ). Abdominal ventrites 1+2 finely punctate, without transverse wrinkles; ventrites 3–5 more strongly microreticulate; ventrite 5 unmodified in both sexes.

Legs very slender. Femora all subequally thick, thickest in about distal two-thirds, untoothed, with protruding setae; inflated median parts polished, not wrinkled. Tibiae straight, without sharp edges, with long erect setae only on outer margin ( Figs. 29 View FIGURES 28–43 , 69 View FIGURES 57–74 ); apical tuft inconspicuous, without a pair of distinct setae. Tarsi narrow, with poorly developed ventral adhesive sole; tarsomere 1 subtruncate or rounded apically, tarsomere 2 emarginate dorsally; bi-lobed tarsomere 3 narrow, inconspicuous ( Figs. 68 View FIGURES 57–74 , 107 View FIGURES 96–111 ); onychium distinctly surpassing length of tarsomere 3, without special apical setae; claws toothed.

Male. Abdominal ventrite 5 broadly rounded or roundly truncate apically. Membrane of tergite VII without median invagination. Pygidium strongly convex, with narrow exposed marginal ridge. Sternite VIII undivided, with broadly separated short lobes. Spiculum gastrale Y-shaped, symmetrical. Tegmen subarticulate; basal piece Y-shaped with short apodeme; tegminal plate generally typical for the most basal apionine lineages: largely nonsclerotized, not developed latero-ventrally, with short and broadly rounded paired parameral lobes ending with crescentic marginal sclerotization bearing long macrochaetae, lacking membranous apical extensions or they are vestigial; fenestral sector spread on entire width of the plate, devoid of delimited “windows” and confluent with transparent bases of parameral lobes; postfenestral plate short, undivided; prostegium broadly membranous medially, with long lateral extensions ( Figs. 40 View FIGURES 28–43 , 77, 90 View FIGURES 75–91 ). Penis with pedon and tectum separated by broad membrane; tectum broad, weakly evenly sclerotized; penile apodemes flattened, indistinctly dichotomous basally; sclerotized connection of the apodemes with tectum full, with pedon subarticulated by a thin sclerotized filament; pedon with canaliculate apex; endophallus large, laying largely outside penile body in repose, with inflatable paired lobes; additional endophallic sclerites present or absent; entrance of ejaculatory duct (gonopore) dorsal, near the base of exposed part of endophallus, not on its apex ( Figs. 44 View FIGURES 44–56 , 79 View FIGURES 75–91 ).

Female. Abdominal ventrite 5 nearly as in male, more regularly rounded. Tergite VIII strongly transverse, with a narrow marginal sclerotization subdivided in middle. Gonocoxites with setose styli. Bursa large, simply membranous. Spermatheca thin, smooth, irregularly c-shaped, without distinct prominences on a narrow corpus.

Biology. Associated with the plant family Celastraceae   . For known details see description of the type species, Rh. variiforme   sp. n.; in the remaining genus members the biology remains unknown.

Distribution. South Africa (R.S.A.), East Africa ( Tanzania).

Etymology. The name expresses great overall similarity of these apionines to the attelabid subfamily Rhynchitinae   , to which they have been frequently assigned in some provisionally sorted museum collections. Gender neuter.