Minyomerus caseyi [JF2015] (Sharp, 1891) 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 : 51-56

Taxon classification Animalia Coleoptera Curculionidae

Minyomerus caseyi [JF2015] (Sharp, 1891) sec. Jansen & Franz (2015) Figs 29, 30

== AND = Pseudelissa caseyi Sharp, 1891: 151 sec. Sharp (1891) (genus synonymized by Pierce, 1909: 359).

Diagnosis.

Minyomerus caseyi [JF2015] is readily distinguished from other congenerics by the presence of apically explanate elytral setae. The corpus of the spermatheca is uniquely elongate.

Redescription - female.

Habitus. Length 3.61-3.96 mm, width 1.52-1.72 mm, length/width ratio 2.31-2.55, widest at anterior 1/4 of elytra. Integument black on tagmata and elytra, light to dark orange-brown on other appendages. Scales with variously interspersed colors ranging from slightly off-white to manila/tan to dark coffee brown, in some specimens appearing to have opalescent reflections. Setae apically explanate, appearing spatulate, sub-recumbent.

Mandibles. Covered with white scales, with 4 longer setae, and 1-2 shorter interspersed setae.

Maxillae. Cardo 2 × 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 2 × longer than outer arm, inner arm 1.5 × width of outer arm, inner arm of bifurcation equal in length to apically outcurved arm. Stipes sub-quadrate, slightly wider than long, roughly equal in length to inner bifurcation of cardo, glabrous. Galeo-lacinial complexmembranous and setose in posterior 3/4, sclerotized and somewhat emarginate anteriorly; dorsally with 8 apicomesal lacinial teeth; ventrally with 3 reduced lacinial teeth. Palpiger with a row of transverse setae; membranous in anterior 1/3.

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; II with 1 mesoventral seta in addition to 2 apical setae.

Labium. Prementum completely covering Maxillary palps; roughly trapezoidal, ventrally broadly convex, planar laterally; apical margin laterally incurved, medially projected (ligula) with a distinct anterior face, angulate. Labial palps 3-segmented, I with apical 1/2 projecting beyond margin of prementum, but not reaching apexof ligula; all 3 segments with 1 apical seta; III slightly longer than II.

Rostrum. Length 0.41-0.47 mm, anterior portion 2.5-3.0 × broader than long, rostrum/pronotum length ratio 0.43-0.49, rostrum length/width ratio 0.92-0.98. Separation of rostrum from head generally obscure. Dorsal outline of rostrum sub-rectangular, anterior half of dorsal surface impressed, posterior half strongly rugose. Rostrum in lateral view nearly square; apical margin broadly bisinuate, with 2 large vibrissae. Nasal plate defined by V-shaped, impressed lines, anteromesally slightly convex, integument partially covered with white scales. Margins of mandibular incision directed 20° outward dorsally in frontal view. Ventrolateral sulci strongly defined as a deep notch or sulcus dorsad of insertion point of mandibles. Dorsal surface of rostrum with short, linear, median fovea. Rostrum ventrally with median fovea near base of rostrum that continuing very shallowly towards posterior margin of head.

Antennae. Small tooth formed by overhanging dorsal margin of scrobe anterior to margin of eye by 1/3 of length of eye. Club similar in length to funicular antennomeres IV-VII, nearly 2.5 × as long as wide.

Head. Eyes globular to ovate, posterior margin level with lateral surface of head, slanted antero-ventrally ca. 45°; eyes separated in dorsal view by 4 × their anterior- posterior length, set off from anterior prothoracic margin by 1/5 of their anterior-posterior length.

Pronotum. Length/width ratio 0.93-0.98; widest between anterior constriction and midpoint. Anterior margin feebly arcuate, lateral margins feebly curved and widening into a slight bulge just anteriad of midpoint of pronotum, posterior margin straight, with a slight mesal incurvature. Pronotum in lateral view with setae that barely reach anterior margin. Anterolateral margin with a reduced tuft of 3-5 ocular vibrissae present, emerging near ventral 1/2 of eye, becoming gradually, evenly longer ventrally, stopping just below ventral margin of eye; vibrissae achieving a maximum length similar to anterior-posterior length of eye.

Scutellum. Minute and not apparent.

Pleurites. Metepisternum nearly hidden by elytron except for triangular extension.

Thoracic sterna. Prosternal process not elevated. Mesocoxal cavities separated by 1/5 × width of mesocoxal cavity. Metasternum with transverse sulcus apparent but obscured somewhat by scales; metacoxal cavities widely separated by 3 × their width.

Legs. Profemur/pronotum length ratio 0.88-0.95; profemur with distal 1/5 produced ventrally as a sub-rectangular projection covering tibial joint; condyle of tibial articulation occupying 2/3 of distal surface and 1/5 length of femur. Protibia/profemur length ratio 0.83-0.91; protibial apexwith ventral setal comb recessed in a subtly incurved groove; mucro reduced to a very small laterally projected tooth. Protarsus with tarsomere III 1.5 × as long as II; wider than long. Metatibial apexwith almond shaped convex ity ringed by 10-12 short, spiniform setae.

Elytra. Length/width ratio 2.84-3.00; widest at anterior 1/4; 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. Posterior declivity, angled at nearly 75° to main body axis. Elytra with 10 complete striae; striae shallow; punctures faint beneath appressed scales, separated by 4-6 × their diameter; intervals very slightly elevated.

Abdominal sterna. Ventrite III anteromesally incurved around a fovea located mesally on anterior margin, posterior margin elevated and set off from IV along lateral 1/4s of its length. Sternum VII mesally 1/2-3/5 × as long as wide; setae darkening, lengthening, and becoming more erect in posterior 1/4; anterior margin weakly curved.

Tergum. Pygidium (tergum VIII) sub-cylindrical, posterior margin cultellate, with a few minute setae inserted along rim.

Sternum VIII. Anterior 9/10 narrowly stylate; posterior 1/10 (lamina) sub-quadrate; anterior edges each forming a 90° angle with lateral margin; sclerotized region with anterior 1/6 less sclerotized; posterior edge mesally incurved.

Ovipositor. Coxites slightly sclerotized, nearly as broad as long; styli 3/4 × length of coxites, glabrous.

Spermatheca. “U” -shaped; collum long, equal in length to cornu, sinuate, narrowed to 1/2 × width of base in apical 1/3, collum sub-contiguous with, and angled at 90° to ramus; ramus bulbous, 1/3 × length of collum; corpus not swollen, of equal thickness to collum and cornu; cornu elongate, narrowed to 2/3 × width of base in apical 1/3, strongly recurved in basal 1/3, straight along apical 2/3, inner angle between cornu and collum nearly 55°.

Male.

Similar to female, except where noted. Length 3.07-3.64 mm, width 1.18-1.42 mm, length/width ratio 1.98-2.60. Rostrum length 0.41-0.53, rostrum/pronotum length ratio 0.49-0.60, rostrum length/width ratio 1.02-1.30. Pronotum length/width ratio 0.97-1.06. Profemur/pronotum length ratio 0.90-0.96, protibia/profemur length ratio 0.79-0.91. Elytra length/width ratio 2.86-3.37.

Elytra. Generally narrower relative to pronotum, but otherwise as female.

Abdomen. Sternum VII slightly more broadly arcuate posteriorly, 3/5 as long as wide. Pygidium (tergum VIII) with posterior margin evenly arcuate; posterior 1/2 punctate; anterior 1/2 rugose.

Aedeagus. Length/width ratio 5.61-5.84; lateral margins very slightly converging posteriorly, widening in region of ostium, then narrowing more strongly into a small posterior projection. In lateral view, width of pedon even in anterior 3/4, ventral margins in posterior 1/4 becoming straight towards apex, then abruptly curving to meet dorsal margins at a sharp apical point; apexacutely angulate. Flagellum apically with a large, narrowly elongate, micro-denticulate sclerite.

Material examined.

"MEXICO, SLP, Hwy 57, 23 mi. SE. San Luis Potosi, 6000', 10 Sept. 1982 C. & L. O’Brien & G. Wibmer" (CWOB: 6 females, 6 males); "MEX. N, Leon, Hwy 57, 79 mi. SW. Linares, X-16-1970/ at night, L & C.W. O’Brien” (CWOB: 1 female); "MEXICO: Vera Cruz, 10 mi. sw. Perote, July 27, 1974, Clark, Murray, Ashe, Schaffner" (TAMU: 1 female).

Distribution.

This species has been found in San Luis Potosí and Nuevo León (Mexico). It is likely to be found throughout the Chihuahuan Desert and arid regions of south-central Mexico based on habitat similarity (Fig. 50).

Natural history.

No host plant associations have been documented.