Minyomerus trisetosus [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 : 56-58

Taxon classification Animalia Coleoptera Curculionidae

Minyomerus trisetosus [JF2015] Jansen & Franz sec. Jansen & Franz (2015) sp. n. Figs 31, 32

Diagnosis.

Minyomerus trisetosus [JF2015] can be differentiated from other congenerics by the presence of long, erect, white setae interspersed among the regular rows of shorter, sub-recumbent, brown setae. Additionaly the procoxae are apparently contiguous, and the margins of the oral cavity are straight and slightly divergent. The anterior margin of the pronotum bears a reduced tuft of post-ocular vibrissae as well as a row of setae inserted 1/2 their length from the anterior margin. The spermatheca has the ramus basally constricted.

Description - female.

Habitus. Length 3.01-3.87 mm, width 1.24-1.70 mm, length/width ratio 2.28-2.44, widest at anterior 1/4-1/3 of elytra. Integument black on tagmata and elytra, light to dark orange-brown on other appendages. Scales with variously interspersed colors ranging from white to manila/tan to dark coffee brown, occasionally opalescent or with undertones of red or yellow, in some specimens appearing semi-translucent (in others opaque). Three kinds of linear setiform scales ( ‘setae’) sparse throughout; first kind short, erect to sub-erect, brown, arranged in rows on elytral intervals, present on dorsum of thorax and head; second sparser and up to 4 × length and ca. 2 × girth of former, longer and thicker on lateral surfaces, erect to sub-erect, white, interspersed among brown setae on dorsum; venter with setae thinner and more setiform than others, of similar length to brown setae, sub-recumbent, translucent white, becoming longer posteriorly and somewhat darker on terminal abdominal segment.

Mandibles. Covered with white to golden scales, with 3 longer setae, and 1 shorter seta ventrad of these.

Maxillae. Cardo 1.5 × as long as distance from base of palpomere I to base of palpiger, bifurcate at base with an inner angle of ca. 90°, inner (mesal) arm longer than outer arm, inner arm of equal width to outer arm, inner arm of bifurcation 2 × length of apically outcurved arm. Stipes sub-quadrate, 0.5 × longer than wide, roughly equal in width to inner arm of bifurcation of cardo, with 1 lateral seta. Galeo-lacinial complexapically incurved (mesally); complex membranous; setose in basal half; dorsally with 8 apicomesal lacinial teeth; ventrally with 4 reduced lacinial teeth. Palpiger with a 1 lateral seta and 1 mesal seta, sclerotized on basal 2/3.

Maxillary palps. I and II both apically oblique, apical ends facing mesally and forming a 45° angle with base, I and II each with 2 apical setae. Labium. Prementum roughly trapezoidal; apical margins sinuate, angulate; lateral margins weakly incurved; basal margin arcuate. Labial palps 3-segmented, I with apical 1/2 projecting beyond margin of prementum, reaching apexof ligula; III slightly longer than II.

Rostrum. Length 0.38-0.52 mm, anterior portion 2.5-3.0 × broader than long, rostrum/pronotum length ratio 0.46-0.53, rostrum length/width ratio 0.91-1.10. Dorsal outline of rostrum sub-rectangular, anterior half of dorsal surface strongly impressed, posterior half strongly rugose. Rostrum in lateral view rectangular; apical margin with 2 large vibrissae. Nasal plate strongly defined by Y-shaped, impressed lines, convex, integument covered with white scales. Margins of mandibular incision curved, directed 30° outward dorsally in frontal view; ventrolateral sulci usually weakly defined as a somewhat shallow to moderately deep, but broad, impression dorsad of insertion point of mandibles. Dorsal surface of rostrum with median sulcus running from fovea at posterior end of nasal plate to midpoint of posterior half of rostrum. Rostrum ventrally lacking foveae in line with insertion point of mandibles.

Antennae. Dorsal margin of scrobe overhangs slightly (broadly, not forming a sharp tooth) ventrad of anterior margin of eye. Funicular antennomeres evenly progressing from elongate to broader than long; terminal funicular segment lacking appressed scales, having instead a covering of apically-directed pubescence with interspersed sub-erect setae. Club nearly 3 × as long as wide.

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

Pronotum. Length/width ratio 0.84-0.91, sub-cylindrical to globular; widest near anterior 2/5; surface rugoso-punctate, though punctures somewhat obscured by scales. Anterior margin slightly arcuate, lateral margins feebly curved and widening into a bulge near anterior 2/5 of pronotum, thence straight to posterior margin, posterior margin incurved mesally. Pronotum in lateral view with sub-erect to erect setae that reach just beyond anterior margin in lateral view, but are inserted less than half their length from anterior margin; these setae becoming evenly longer laterally, attaining a maximum length 3/5 × anterior-posterior length of eye. Anterolateral margin with a reduced tuft of post-ocular vibrissae present, consisting of 3-5 setae, emerging dorsad ventral margin of eye, becoming longer ventrally, stopping just beneath ventral margin of eye; vibrissae achieving a maximum length 2/5-3/5 × anterior-posterior length of eye.

Scutellum. Hidden in some specimens, narrowly exposed in others (visible area less than 2 × length of appressed scales), margins straight.

Pleurites. Metepisternum covered by elytron near posterior 1/6 of metasternum.

Thoracic sterna. Mesocoxal cavities separated by distance1/3-1/2 × width of mesocoxal cavity. Metasternum without apprent transverse sulcus; metacoxal cavities widely separated by 3-4 × their width.

Legs. Profemur/pronotum length ratio 0.87-0.96; proximal 5/6 of profemur gradually widening, then abruptly constricted with distal 1/6 produced ventrally as a short, nearly semicircular projection covering tibial joint; condyle of tibial articulation occupying 1/6 length of femur. Protibia/profemur length ratio 0.84-0.90; protibia with ventral setal comb situated on a curved edge; mucro reduced to a very small laterally projected tooth. Protarsus with tarsomere I slightly longer than II; I and III similar in length, III equilateral. Metatibial apexwith thin, almond shaped convex ity narrowly ringed by 6-8 short, widely separated, spiniform setae.

Elytra. Length/width ratio 2.79-3.23; widest at anterior 1/3; anterior margins jointly 1.5-1.75 × wider than posterior margin of pronotum; lateral margins sub-parallel after anterior 1/4, more strongly rounded and converging in posterior 1/2. Elytra in lateral view sculpted with a depression at anterior 1/4; posterior declivity angled at nearly 80° to main body axis. Elytral striae not well defined, punctures not visible beneath scales, separated by 3-4 × their diameter; elytral suture sometimes slightly elevated; each interval medially with a row of erect to sub-erect setae.

Abdominal sterna. Ventrite III with posterior margin slightly elevated and set off from IV along lateral 1/3s of its length; anterior margin of V incurved. Sternum VII mesally 1/2 × as long as wide, sub-trapezoidal; anterior margin weakly curved; poste rior margin mesally nearly straight, laterally arcuate. Tergum. Pygidium (tergum VIII) sub-conical; medial 1/3 of anterior 2/3 of pygidium less sclerotized.

Sternum VIII. Lamina sub-rectangular; anterior edges each incurved forming a 90° angle with lateral margin, not produced to a point anteromedially at connection to spiculum ventrale; less sclerotized medially.

Ovipositor. Coxites in dorsal view 2 × as long as broad; styli 3/4 × length of coxites, with 3-5 long setae near base.

Spermatheca. Comma-shaped; collum short, not readily distinguished, apically with hood-shaped projection sub-parallel to ramus, 2/3 × length of ramus and contiously aligned with curvature of bulb of ramus; collum sub-contiguous with, and angled at 90° to ramus; ramus bulbous, sharply constricted beneath, as long as 1.5 × length of corpus and collum, as wide as length of corpus and collum; corpus not swollen, of equal thickness to cornu; cornu elongate, apically slightly narrowed, strongly recurved in basal 1/4, nearly straight thereafter, forming a nearly 45° angle with corpus and collum.

Male.

Not available or known.

Etymology.

Named in reference to the three distinct types of setae present on the body; tri- = three, setosus = bristly, hence trisetosus = with three kinds of bristles; Latin adjective ( Brown 1956).

Material examined.

Holotype - female "TEX. Lamb Co. 9 mi. W Littlefield, IV-21-1971, C.W. O’Brien” (CWOB). Paratypes, same label information as female holotype (CWOB: 4 females); "TEX. Lubbock, 12-18-1970, pitfall trap, C.W. O’Brien” (CWOB: 6 females); "TEX. Howard Co., 4 mi. S. Big Spring, V-2-1971 night, O’Brien & Marshall" (CWOB: 20 females) [8 females deposited at CMNC]; "TEX. Howard Co., 5 mi. S. Big Spring, V-2-1971 night, O’Brien & Marshall" (CWOB: 9 females); "NM: Lea Co., 19 m Denver City Hwy., 20-X-1980, 2:45 pm, Tony Martin, warm, cloudy, snkweed" (NMSU: 19 females); "TEX. Hangford Co., 8 mi. W. Spearman, VI-3-1971, C.W. O’Brien” (TTUZ: 17 females).

Distribution.

This species has been found in the desert and arid regions of New Mexico and Texas (USA). It is likely that its range also includes northern Chihuahua and Coahuila (Mexico), based on similarity in habitat to the currently known distribution (Fig. 50).

Natural history.

Associated with broomweed ( Xanthocephalum [non-focal] sp.; Asteraceae [non-focal]), creosote bush ( Larrea tridentata (DC.) Coville [non-focal]; Zygophyllaceae [non-focal]), and snakeweed ( Gutierrezia [non-focal] sp.; Asteraceae [non-focal]). This species is putatively considered parthenogenetic, given the lack of male specimens across a range of sampling events.