Minyomerus politus [JF2015] Jansen & Franz sec. Jansen & Franz (2015)

Jansen, M. Andrew & Franz, Nico M., 2015, Phylogenetic revision of Minyomerus Horn, 1876 sec. Jansen & Franz, 2015 (Coleoptera, Curculionidae) using taxonomic concept annotations and alignments, ZooKeys 528, pp. 1-133 : 68-74

Taxon classification Animalia Coleoptera Curculionidae

Minyomerus politus [JF2015] Jansen & Franz sec. Jansen & Franz (2015) sp. n. Figs 38, 39, 40

Diagnosis.

Minyomerus politus [JF2015] can be distinguished by the protuberant frons, impressed nasal plate, smooth, unsculpted elytra, and minute, white, elytral setae. The spermatheca is distinct, with the ramus elongate and apically swollen, and the corpus possessing an annulate, cylindrical projection nearly 1/2 × length of the ramus. The aedeagal flagellum is unique in possessing a spiriform apical sclerite that spirals clockwise and is as long as the aedeagal pedon.

Description - female.

Habitus. Length 3.77-4.13 mm, width 1.53-1.70 mm, length/width ratio 2.35-2.47, widest at anterior 1/4 of elytra. Integument dark reddish-brown to black. Scales opaque white with semi-metallic golden scales interspersed throughout, occasionally semi-translucent, appearing black, with opalescent reflections. Linear setiform scales ( ‘setae’) sparse throughout, minute, sub-erect to sub-recumbent, translucent, white, arranged in rows on elytral intervals, longer on humeri and venter.

Mandibles. Covered with white scales, with 3 long setae.

Rostrum. Length 0.44-0.55 mm, anterior portion 1.75-2 × broader than long, slightly narrower than head, rostrum/pronotum length ratio 0.50-0.58, rostrum length/width ratio 1.08-1.20. Dorsal outline of rostrum sub-rectangular, anterior half of dorsal surface mesally concave and impressed, posterior half strongly convex and rugose. Rostrum in lateral view sub-trapezoidal; anterior half of dorsolateral margins slightly diverging; apical margin roughly bisinuate, with 2 large vibrissae. Nasal plate defined by V-shaped, impressed lines, medially slightly concave, integument covered with white scales. Margins of mandibular incision curved, directed 30° outward dorsally in frontal view, bounded by same type of scales as those on remainder of body surface. Ventrolateral sulci strongly defined, beginning as a narrow sulcus dorsad of insertion point of mandibles, running parallel to scrobe, disappearing ventrally. Ventrolateral margins narrowly converging. Rostrum ventrally lacking foveae in line with insertion point of mandibles.

Antennae. Dorsal margin of scrobe overhanging slightly and forming a minute tooth, ventrad of anterior margin of eye. Club 2.5 × as long as wide.

Head. Eyes separated in dorsal view by 3-4 × their anterior-posterior length, set off from anterior prothoracic margin by 2/5-1/2 of their anterior-posterior length. Head between eyes rugose and strongly bulging.

Pronotum. Wider than long, length/width ratio 0.83-0.88, sub-cylindrical to slightly globular; median sulcus absent. Anterior margin arcuate and somewhat produced dorsally, lateral margins evenly curved and widening into a bulge near midpoint; posterior margin straight. Pronotum in lateral view with setae inserted 2 × their length from anterior margin. Anterolateral margin with a reduced tuft of post-ocular vibrissae present, consisting of 3-5 setae, emerging near ventral 1/4 of eye, stopping just beyond ventral margin of eye; vibrissae achieving a maximum length 1/2-3/5 × anterior-posterior length of eye.

Scutellum. Not exposed.

Pleurites. Metepisternum covered by elytron near posterior margin of metasternum.

Thoracic sterna. Mesocoxal cavities separated by distance 1/2 × width of mesocoxal cavity. Metasternum with transverse sulcus somewhat obscure; metacoxal cavities separated by 2.5-3.0 × their width.

Legs. Tibiae and trochanters of all legs with a single, hair-like, brown seta positioned on mesal surface, approximately 1.5-2 × length of adjacent setae. Profemur/pronotum length ratio 0.99-1.15; profemur with distal 1/5 produced ventrally as a rounded projection covering tibial joint; condyle of tibial articulation occupying 2/3 of distal surface and 1/5 length of femur. Protibia/profemur length ratio 0.84-0.97; mucro present as a laterally projected tooth sub-equal in length and nearly 2 × as wide as nearby setae, triangular. Metatibial apexwith almond shaped convex ity ringed by 9-11 short, spiniform setae.

Elytra. Length/width ratio 2.96-3.04; widest at anterior 1/4; anterior margins jointly 1.5-1.75 × wider than posterior margin of pronotum; lateral margins slightly converging after anterior 1/4, more strongly rounded and converging in posterior 1/2. Posterior declivity angled at 45-50° to main body axis. Elytral striae minutely punctate; punctures separated by 6-10 × their diameter; intervals not noticeably elevated.

Abdominal sterna. Ventrite III elevated and set off from IV along lateral 1/3 of its length, somewhat concave anteriorly. Sternum VII mesally 1/2 as long as wide; anterior margin straight.

Tergum. Pygidium (tergum VIII) sub-cylindrical; medial 1/3 of anterior 2/3 of pygidium less sclerotized.

Sternum VIII. Lamina sub-trapezoidal; anterior edges each incurved forming a 105° angle with lateral margin; sclerotized region with pores anteriorly. Ovipositor. Coxites 1/3 as broad as long in dorsal view and with sclerotized regions porose; styli with a patch of pores near base.

Spermatheca. Comma-shaped; collum short, apically with a tongue-shaped projection perpendicular to ante-apical projection, nearly equal in length and contiously aligned with curvature of ante-apical projection; spermatheca ante-apically with a long, elongate-conical projection, angled at ca. 25° to ramus, slightly longer than collum and 1/2 length of ramus; collum short, cylindrical, sub-contiguous with, and angled at 90° to ramus; ramus elongate, length 2 × width of corpus, basal 1/2 equal in width to corpus, apical 1/2 slightly bulbous; corpus swollen, slightly thicker than collum, wider than cornu; cornu elongate, apically, gradually narrowed, strongly recurved near mesal 1/3, forming an inner angle of ca. 90° to collum and corpus, slightly incurved near apical 1/3.

Male.

Similar to female, except where noted. Length 2.61-3.40 mm, width 1.01-1.32 mm, length/width ratio 2.54-2.57. Rostrum length 0.41-0.53 mm, rostrum/pronotum length ratio 0.65-0.71, rostrum length/width ratio 1.16-1.38. Pronotum length/width ratio 0.82-0.88. Profemur/pronotum length ratio 1.12-1.33, protibia/profemur length ratio 0.82-0.90. Elytra length/width ratio 2.72-3.12.

Elytra. Elytral declivity slightly more angulate, forming a 65° angle to main body axis, but otherwise as female. Abdomen - sternum IV relatively shorter, mesally slightly longer and laterally shorter than V and VI jointly. Sternum VII 2/5-1/2 × as long as wide. Pygidium (tergum VIII) posterior 2/3 punctate; anterior 1/3 rugose.

Sternum VIII. Dorsal surface with a patch of short, fine setae laterally. Aedeagal pedon. Length/width ratio 3.37. Ventral margins in region of ostium straight. Flagellum with a large, narrowly elongate, tortuous, spiriform sclerite, sclerite anteriorly gradually widened and more sclerotized, constricted slightly in anterior 1/3 and slightly widening anteriorly to form a small bulb and long counterclockwise-spiraling projection, situated in anterior portion of flagellum, and as long as pedon.

Comments.

Due to the limited number of specimens of this species, dissections of mouthparts could not be performed.

Etymology.

Named in reference to the smooth body surface and imperceptibly minute setae; politus = polished; Latin adjective ( Brown 1956).

Material examined.

Holotype - female "NV: Clark Co. Jcn., I-15 & Hwy. 169, 24-IV-2005, C.W. O’Brien / on Franseria dumosa Gray [non-focal]" (CWOB). Paratypes, same label information as female holotype (CWOB: 1 female, 1 male); "NV: Clark Co. Jcn., I-15 & Hwy. 93, exit 64, east, small dunes, IV-8-2005/ C.W. O’Brien, Collector" (CWOB: 2 females, 2 males).

Distribution.

This species is known from a single locality in Clark County, Nevada (Fig. 52).

Natural history.

Associated with burro-weed ( Ambrosia dumosa [A. Gray] W.W. Payne [non-focal]; Asteraceae [non-focal]).