Minyomerus conicollis [JF2015] Green, 1920 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 : 25-31

Taxon classification Animalia Coleoptera Curculionidae

Minyomerus conicollis [JF2015] Green, 1920 sec. Jansen & Franz (2015) Figs 12, 13, 14, 15

== Minyomerus conicollis Green, 1920: 194 sec. Green (1920)

Diagnosis.

Minyomerus conicollis [JF2015] is readily distinguished from other congenerics by the highly convex elytra, and by the pronotum, in which the posterior margin is distinctly shorter than the anterior margin. The spermatheca is uniquely comma-shaped, with the ramus reduced, apically flattened and sub-contiguous with the collum. The aedeagus is unique in being membranous ventrally, and not fully sclerotized.

Redescription - female.

Habitus. Length 2.80-3.42 mm, width 1.02-1.27 mm, length/width ratio 2.64-2.76, widest at anterior 1/5-1/4 of elytra. Integument orange-brown to black. Scales with variously interspersed colors ranging from white to manila/tan to dark coffee brown, in some specimens appearing semi-translucent (in others opaque) or with metallic reflections. Setae sub-recumbent.

Mandibles. Covered with opalescent scales, with 6 longer setae.

Maxillae. Cardo bifurcate at base with an inner angle of ca. 100°, inner (mesal) arm 2 × longer than outer arm, inner arm of equal width to outer arm, inner arm of bifurcation equal in length to apically outcurved arm. Stipes square, roughly equal in length to inner arm of bifurcation of cardo, with a single lateral seta. Galeo-lacinial complex apically incurved (mesally); complex membranous; setose in basal 2/3; dorsally with 8 apicomesal lacinial teeth; ventrally with 3 reduced lacinial teeth. Palpiger with a transverse row of 3 setae, sclerotized on basal 2/3.

Maxillary palps. Palpomeres I and II with apical ends facing mesally and forming a 45° angle with base, each with 1 apical seta; II with 1 mesoventral seta in addition to apical seta.

Labium. Prementum roughly trapezoidal, ventrally sub-planar throughout; apical margins sinuate, strongly angulate; lateral margins incurved; basal margin mesally nearly straight. Labial palps 3-segmented, I with apical 1/2 projecting beyond margin of prementum, reaching past apex of ligula; III slightly longer than II.

Rostrum. Length 0.40-0.48 mm, anterior portion 2-2.25 × broader than long, rostrum/pronotum length ratio 0.56-0.69, rostrum length/width ratio 1.01-1.24. Dorsal outline of rostrum sub-rectangular, anterior half of dorsal surface strongly impressed, posterior half sometimes weakly rugose. Rostrum in lateral view rectangular; apical margin with 2 large vibrissae. Nasal plate strongly defined by V-shaped, impressed lines, convex, integument completely covered with scales similar to those of body. Margins of mandibular incision directed 30° outward dorsally in frontal view; ventrolateral sulci usually undefined or weakly defined, beginning as a broad, shallow sulcus dorsad of insertion point of mandibles, running parallel to scrobe, becoming fainter posteriorly and disappearing ventrally; occasionally with a short, well defined sulcus dursad of insertion point of mandibles. Dorsal surface of rostrum with median sulcus present as a short, linear fovea posteriad of base of nasal plate; ventrolateral margins slightly converging anteriorly. Rostrum ventrally lacking sulci at corners of oral cavity. Oral cavity with lateral margins strongly curved.

Antennae. Dorsal margin of scrobe overhangs slightly (broadly, not forming a sharp tooth) ventrad of anterior margin of eye. Club similar in length to funicular antennomeres IV-VII, nearly 2.5 × as long as wide.

Head. Eyes separated in dorsal view by 4 × their anterior-posterior length, touching anterior prothoracic margin.

Pronotum. Slightly, but distinctly, longer than wide, length/width ratio 0.84-0.90, sub-conical; widest just anteriad of midline; median sulcus present, sometimes obscure. Anterior margin arcuate, subtly incurved medially, lateral margins feebly curved and widening into a slight bulge just anteriad of midline, thence straight to posterior margin, posterior margin straight and shorter than anterior margin. Pronotum in lateral view with setae that just reach anterior margin at their maximum length. Anterolateral margin with a reduced tuft of post-ocular vibrissae present, consisting of 5-7 setae, emerging near ventral 1/3 of eye, becoming gradually, evenly longer ventrally, stopping just beneath ventral margin of eye; vibrissae achieving a maximum length 2/3-3/4 × anterior-posterior length of eye.

Scutellum. 1.5-2 × longer than wide at base, margins straight.

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

Thoracic sterna. Mesocoxal cavities separated by distance 1/4-1/3 × width of mesocoxal cavity. Metasternum without apprent transverse sulcus; metacoxal cavities widely separated by 1.75-2.25 × their width.

Legs. Profemur/pronotum length ratio 0.98-1.06; profemur with distal 1/5 produced ventrally as a nearly square projection covering tibial joint. Protibia/profemur length ratio 0.83-0.90; mucro reduced to a small laterally projected tooth. Protarsus with tarsomere I nearly 1.5 × as long as II; I and III similar in length, III equilateral; I-III jointly similar in length to V. Metatibial apex with almond shaped convex ity ringed by 7 short, widely separated, spiniform setae.

Elytra. Length/width ratio 3.21-3.46; widest at anterior 1/5-1/4; anterior margins jointly 2 × wider than posterior margin of pronotum; lateral margins sub-parallel after anterior 1/5, more strongly rounded and converging in posterior 1/2. Elytra in lateral view sculpted with a depression at anterior 1/3; posterior declivity angled at nearly 60° to main body axis. Elytral striae defined, punctate; punctures visible, deep and distinct in some specimens, separated by 3-6 × their diameter.

Abdominal sterna. Ventrite III elevated and set off from IV along lateral 1/4-1/3s of its length. Sternum VII mesally 1/2 × as long as wide, with a strong medial concavity; anterior margin weakly curved.

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

Sternum VIII. Anterior laminar edges each incurved forming a 100° angle with lateral margin; less sclerotized medially between arms; posterior edge medially incurved.

Ovipositor. Coxites slightly sclerotized, in dorsal view 2 × as long as broad.

Spermatheca. Comma-shaped; collum short, apically with a reduced hood-shaped projection; collum sub-contiguous with, and angled at 90° to ramus; ramus bulbous, slightly larger than collum and corpus; corpus swollen, of nearly equal thickness ramus and cornu; cornu elongate, apically gradually narrowed, strongly recurved in basal 1/4, gently curved along mesal 1/2, and curved and somewhat flattened near apical 1/4 such that apex is sub-parallel to hood-shaped projection of collum.

Male.

Similar to female, except where noted. Length 2.41-2.85 mm, width 0.90-0.99 mm, length/width ratio 2.53-2.94. Rostrum length 0.38-0.48 mm, rostrum/pronotum length ratio 0.58-0.81, rostrum length/width ratio 1.11-1.31. Pronotum length/width ratio 0.82-1.00. Profemur/pronotum length ratio 1.01-1.21, protibia/profemur length ratio 0.86-0.91. Elytra length/width ratio 2.90-3.30.

Elytra. Elytral declivity slightly more angulate, forming a 70° angle to main body axis, but otherwise as female.

Abdomen. Sternum VII slightly more broadly arcuate posteriorly, 1/2 as long as wide. Tergum VII with posterior margin straight. Pygidium (tergum VIII) with posterior 1/2 punctate; anterior 1/2 rugose.

Sternum VIII. Consisting of 2 sub-contiguous, sub-triangular sclerites; posterior margins widely angulate. These projections located on lateral 2/5s of posterior margin, as long as sub-quadrate portion of lamina. Mesal 1/5 with a short, sub-trapezoidal projection.

Aedeagus. Length/width ratio 3.07-4.62; lateral margins gently converging posteriorly, abruptly more strongly converging posteriad of ostium. Width of pedon in lateral view becoming gradually narrower posteriorly in anterior 5/6, ventral margins in posterior 1/6 curved sharply outwardly to form a lobe, then abruptly curving to meet dorsal margins at a sharp apical point. Ostium elongate, basally open (sclerotized pedon not baso-ventrally entire), laterally emarginate, apical edge with a recurved invagination. Flagellum apically with a large, narrowly elongate, tortuous, ampullate sclerite, sclerite anteriorly gradually widened and recurved to form a small bulb, situated in anterior portion of flagellum.

Comments.

This species exhibits some variation in the sculpture of the prothorax, which can be more or less rugose depending on the specimen.

Material examined.

Paratypes - 1 female "Green Val, VII 15 Tex/ Brewster Co., J.W. Green/ Paratype, Minyomerus conicollis Green. [red]/ J.W. Green Collection/ Minyomerus conicollis " (CAS); "Green Val, VII 15 Tex/ Brewster Co., J.W. Green/ Paratype, Minyomerus conicollis, Green. / USNM, Paratype, 54992/ Minyomerus conicollis Green " (USNM: 1 female). Additional specimens examined: "Tex. 57 mi S Alpine, Brewster Co. 6-6-1970/ Collectors: L&C.W. O’Brien” (CWOB: 2 males); "Tex. 51 mi S Alpine, Brewster Co. 6-6-1970/ Collectors: L&C.W. O’Brien” (CWOB: 2 males); "TEXAS: Rio Grande Vill., Big Bend Nat’l. Park, June 7, 1972, W. E. Clark" (TAMU: 19 females, 27 males); "TEXAS: Rio Grande Villiage, Big Bend Nat’l. Park, 8-VI-1972, W. E. Clark" (TAMU: 1 female); "12 miles nw., Presidio, Texas, June 24, 1968, J. E. Hafernik (TAMU: 1 female)"; "6 miles south of Dell City, Texas, VI-29-1991, Creosote Bush, W.F. Chamberlain" (TAMU: 4 females, 4 males); "TEXAS: Brewster Co., Black Gap Wdlf. Mgt. Ar., VI-5-1994, Coll. E. G. Riley" (TAMU: 1 male); "3 miles north Presidio, Texas, June 17, 1968, J.E. Hafernik" (TAMU: 7 females, 6 males): "3 miles north Presidio, Texas, June 13, 1968, J.E. Hafernik" (TAMU: 5 females, 3 males): "12 mi. s. Marfa, Texas IX-30-66, C. L. Cole" (TAMU: 1 female).

Distribution.

This species has been found in the Big Bend region of Texas (USA), and is likely also found in Coahuila and Chihuahua (Mexico) (Fig. 51).

Natural history.

Associated with creosote bush ( Larrea tridentata [DC.] Coville [non-focal]; Zygophyllaceae [non-focal]).