Rhynchitapion usambarense, Wanat, 2021

Wanat, Marek, 2021, New basal taxa of South African Apioninae (Coleoptera: Curculionoidea: Brentidae), Zootaxa 5035 (1), pp. 1-60: 19-23

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Rhynchitapion usambarense

sp. n.

Rhynchitapion usambarense   sp. n.

( Figs. 89–111 View FIGURES 75–91 View FIGURES 92–95 View FIGURES 96–111 , 291 View FIGURES 289–296 )

Type material. Holotype ♂ (labels as in Fig. 111 View FIGURES 96–111 ): a) Usambara / Kraatz; b) Coll. J. Faust / Ankauf 1900; c) Paraty- pus; d) Staatl. Museum für/ Tierkunde Dresden; e) type label by M.Wanat ( SMTD). Abdominal ventrites stuck to a separate card; genitalia in a drop of Canada balsam, on a transparent card pinned under specimen.  

Remarks. On the 13 th of May 2020, the type specimen was incidentally crushed by the author and lost, after taking its measurements and photographs (including SEM micrographs) for the purpose of this description. The only parts left on the card are antennae (one nearly complete) and two tarsi. Only one elytron was finally found on the carpet floor, it has been glued to the original card. The abdominal ventrites and genital preparation remained safely mounted on other cards.

This unlucky specimen was originally put among the type series of Apion kwaiense Hartmann, 1904   in the historical collection of J. Faust at SMTD and apparently mislabelled as a paratype of this completely dissimilar and unrelated species, though without any specific name   .

Diagnosis. The only species of Rhynchitapion   occurring in East Africa, known from a single male, but clearly distinct from its variable South African congeners. The most evident differences concern uniformly brown entire body, poorest erect setation (although its state in the holotype is partly due to abrasion during its subsequent preparations), rostrum shorter than pronotum and only 2.6 × as long as wide, relatively shorter scape and some other antennal segments, sparse and superficial punctures on the base of pronotal disc, accompanied with distinct microreticulation, penile pedon only 3 × as long a broad, apically broadly rounded and not sinuate in profile, and endophallus with several irregular sclerites.

See also the key to Rhynchitapion species   below.

Description. Body 2.30 mm long, entire uniformly brown-testaceous, with slightly lighter antennae and legs ( Fig. 96 View FIGURES 96–111 ). Erect hair-like setae all light, much shorter and sparser than in preceding species (on pronotum and elytra of the holotype partly abraded), on head retained only behind eyes, on legs even shorter and semi-erect.

Morphological indices of ♂ holotype (n=1): rl/pl: 0.91; rl/mxrw: 2.60; scl/msrw: 0.79; msrw/mtrw: 1.09; msrw/arw: 1.05; msrw/minrw: 1.09; msrw/eyl: 0.95; brl/eyl: 1.20; eyl/hl: 0.9; frw/mtrw: 0.86; hl/hw: 0.82; mpw/hw: 1.16; bpw/apw: 1.03; pl/mpw: 1.19; mew/mpw: 1.79; el/pl: 2.67; el/mew: 1.77; mew/bew: 1.39; bew/ mpw: 1.29; pft/msrw: 1.01; ptbl/pl: 1.05; ptbl/ptbmw: 5.33.

Rostrum flattened, nearly straight ( Fig. 102 View FIGURES 96–111 ), narrowest at middle of metarostrum ( Fig. 100 View FIGURES 96–111 ); prorostrum nearly impunctate along middle line of its dorsal side ( Fig. 99 View FIGURES 96–111 ), densely confusedly punctate laterally and ventrally, without ventral median rib but with a narrow median impunctate line; antennal pits distinctly elongate; scrobes broad and shallow, with obtuse upper edges, their septum microreticulate, flat, impunctate, with a confused double row of minute setae; the extreme base of rostrum ventrally with shallow punctures ( Fig. 92 View FIGURES 92–95 ).

Antennae 0.85 × as long as elytra, unicoloured, with protruding setae ( Figs. 93 View FIGURES 92–95 , 99 View FIGURES 96–111 ); antennal insertion 0.46; length/width ratio: scape 3.0, fun1 2.7, fun2 2.8, fun6 2.0, fun7 1.5, club 5.6; length of scape/fun1 1.3, fun1/fun2 0.9; fun3–fun6 all similar, about 0.9 × as long as fun1; fun7 shorter, 0.65 × as long as fun1; club longer than combined length of four most distal funicular joints, its two basal segments somewhat fusiform.

Head transverse; eyes regularly convex; epifrons between eyes flat, impunctate, microreticulate, with very shallow and irregular longitudinal furrows; vertex flat, behind eyes on half its length with small setiferous punctures and microreticulation ( Fig. 100 View FIGURES 96–111 ); temples with only few small setiferous punctures close to eye margin, very indistinctly wrinkled behind ( Fig. 102 View FIGURES 96–111 ); gular sector convex, with sparse short semi-recumbent setae, without evident transverse wrinkles; subocular protruding setae missing ( Fig. 92 View FIGURES 92–95 ).

Pronotum weakly rounded in middle; anterior 0.6 part smooth, nearly impunctate, in front of subapical constriction finely microreticulate; posterior 0.4 part distinctly microreticulate, with sparse superficial setiferous punctures separated from each other by a few puncture diameters ( Fig. 101 View FIGURES 96–111 ); prosternum about 2 × shorter than hypomeron, not distinctly declining posterad; prosternellum small, button-like, not obviously protruding; hypomeron with obsolescent procoxal rim and punctuation ( Fig. 94 View FIGURES 92–95 ).

Scutellar shield flat, concolorous with pronotum and elytra.

Elytra elongate, gently convex, with indistinct separate caudal part, widest slightly behind middle ( Figs. 96, 97 View FIGURES 96–111 ); striae narrow, weakly impressed, without sharp edges, their anterior portions seemingly enlarged with the visible internal integumental chambers, posterior portions linear; apical junctions of striae 1+10, 2+9, and 3+8 distinctly enlarged ( Fig. 98 View FIGURES 96–111 ); intervals weakly convex, impunctate, interval 1 weakly raised along suture in middle third part of its course.

Wings not examined.

Mesoventrite with several coarse punctures on each side partly covered with hind pronotum margin, largely impunctate in middle; anapleural sutures invisible. Metaventrite almost impunctate even on sides, with the rim of mesocoxae not separated with a line ( Fig. 95 View FIGURES 92–95 ). Abdomen 1.3 × as long as wide ( Fig. 109 View FIGURES 96–111 ); ventrites 1–2 impunctate, finely shagreened; ventrites 3–4 impunctate, heavily microreticulate; ventrite 5 microreticulate on sides, shiny in middle, along apical margin additionally with several irregular, thin transverse asperities; ventrites 3–5 with laterotergites distinctly higher than in two congeners, on ventrite 5 ending far from its apical margin ( Fig. 110 View FIGURES 96–111 ).

Legs slightly shorter and thicker than in Rh. pallidum   sp. n. Femora clavate, smooth except for both shagreened ends, with semi-recumbent or half-erect setae shorter than in other species of Rhynchitapion   ; profemur 2.5 × as long as high. Tibiae without outer and inner edges, with long semi-erect setae present on metatibia, lacking on protibia probably due to abrasion; protibia weakly curved inwards apically, with a narrow stripe of dense white setae along inner margin ( Fig. 108 View FIGURES 96–111 ). Protarsus 4.1 × as long as wide ( Fig. 107 View FIGURES 96–111 ); two basal tarsomeres weakly widening distad, both with a dark median dot on apical margin as in Rh. pallidum   sp. n.; length/width ratio of tarsomeres: 1st—3.0, 2nd—1.8, 3rd—0.8; onychium protruding beyond tarsomere 3 by 0.5 × its length; claws with small triangular teeth.

Male. Tibial mucrones as in other Rhynchitapion species   ; protibial mucro relatively long ( Figs. 106, 108 View FIGURES 96–111 ). Ventrite 5 gently convex, broadly and almost regularly rounded apically, on inner side with transverse subapical carina running some distance from apical margin of ventrite, visible dorsally as darker line blurred in middle ( Fig. 109 View FIGURES 96–111 ). Pygidium in posterior view and sternite VIII, with paired oval additional sclerites in its membrane, as in Fig. 105 View FIGURES 96–111 . Spiculum gastrale with apodeme 2.5 × longer than fork, bent apically; forked arms straight, one with small triangular expansion near base ( Fig. 89 View FIGURES 75–91 ). Tegminal plate as in Figs. 90 & 91 View FIGURES 75–91 ; parameral lobes with suprafenestral sclerites asymmetrically arched; macrochaetae up to 8 on each lobe; lateral extensions of prostegial sclerotizations passing through entire fenestral sector and reaching suprafenestral sclerites; postfenestral plate weakly sclerotized, with defined both its anterior and posterior margin; prostegium with long lateral sclerotized tails. Penile apodemes as long as pedon; pedon 3.0 × as long as wide, parallel-sided and broadly rounded apically, in profile straight in apical half; endophallus in repose projecting far beyond the apices of apodemes, with 8 subequally sized sclerites, 6 of them aggregated at the level of pedon base in repose, separate pair thin and c-shaped, laying evidently outside of pedon ( Figs. 103, 104 View FIGURES 96–111 ).

Female unknown.

Biology. Unknown.

Distribution. Tanzania: Usambara Mts. ( Fig. 291 View FIGURES 289–296 ).

Etymology. Locotypical, after the Usambara Mountains.

Key to species of Rhynchitapion  

1 All body parts testaceous or brown. Erect setae sparse, all light. Aedeagus rounded apically.......................... 2

- At least head with rostrum, legs, and antennal club blackish. Erect setae dense, most of them dark. Aedeagus broadly truncate apically............................................................................. Rh. variiforme   sp. n.

2 Elytra pale testaceous with darker suture and median flecks. Rostrum parallel-sided, at least 3.4 × as long as wide, longer than pronotum. Endophallus with a pair of frenal sclerites........................................... Rh. pallidum   sp. n.

- Elytra uniformly brown. Rostrum expanding distad, 2.6 × as long as wide, shorter than pronotum. Endophallus with eight sclerites.............................................................................. Rh. usambarense   sp. n.