Minyomerus microps [JF2015] (Say, 1831) 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 : 34-41

Taxon classification Animalia Coleoptera Curculionidae

Minyomerus microps [JF2015] (Say, 1831) sec. Jansen & Franz (2015) Figs 19, 20, 21, 22

== (INT) AND> (OST) AND = Thylacites microps Say, 1831: 9 sec. Say (1831) (transferred to Minyomerus Blackwelder and Blackwelder [1948] on the authority of Buchanan in litt. by Blackwelder and Blackwelder, 1948: 46)

== (INT) AND> (OST) AND = Thylacites microsus Boheman, 1833: 523 sec. Boheman (1833) (synonymized by LeConte, 1859: 286)

== (INT) AND> (OST) AND = Minyomerus innocuus Horn, 1876: 18 sec. Horn (1876) (formerly recognized type, designated by Pierce, 1913: 400), syn. n.

Nomenclatural and taxonomic emendations.

Taxonomic comparison of the type specimen of Minyomerus microps and the holotype of Minyomerus innocuus reveals that they are conspecific in the context of the present revision. We therefore propose that Minyomerus innocuus sec. Horn (1876) be changed to junior synonymy of Minyomerus microps [JF2015]. The Discussion further elucidates the historical and present use and status of this species.

Diagnosis.

Minyomerus microps [JF2015] is best differentiated from other congenerics by a combination of characters. The pronotum is anteriorly constricted, and has a reduced tuft of post-ocular vibrissae present on the anterior margin. The elytral setae are small, subrecumbent, and linear. The scales have a unique optical property that gives them a very ‘crusty’ appearance generally. The elytra and prothorax are often quite bulky compared to other species, and the elytral striae are often roughly and broadly sculpted, but not punctate. The spematheca is also very distinctive in having the ramus and collum appearing as two subcontiguous apically invaginated bulbs.

Redescription - female.

Habitus. Length 3.73-4.02 mm, width 1.834-1.557 mm, shape sub-cylindrical to ovate, length/width ratio 2.18-2.40, widest at anterior 1/4 of elytra. Integument dark brown to black. Scales with variously interspersed colors ranging from slightly beige to grey to dark coffee brown, in some specimens appearing semi-translucent (in others opaque) or having blue-green hues, optical effect of scales giving a distinctly ‘crusty’ appearance. Setae sub-recumbent.

Mandibles. Covered with elliptical, beige scales, with 2 pairs of longer setae, and a 1 shorter seta between these pairs.

Maxillae. Cardo 2 × as long as distance from base of palpomere I to base of palpiger, as wide as palpomere III, bifurcate at base with an inner angle of ca. 135°, inner (mesal) arm 3 × length of outer arm, inner arm as thick as outer arm, inner arm of bifurcation equal in length to apically outcurved arm. Stipes sub-quadrate, slightly longer than wide, roughly equal in length to inner arm of bifurcation of cardo, with 1 lateral seta. Galeo-lacinial complex membranous, with sharp demarcation separating palpiger from galeo-lacinial complex; setose in posterior 2/3; dorsally with 8 apicomesal lacinial teeth; ventrally with 1 reduced lacinial tooth. Palpiger with a transverse row of setae extending laterally just posteriad of palpomere I.

Maxillary palps. Three-segmented; 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 roughly pentagonal; apical margin nearly straight, angulate; each basolateral region with 1 long seta. Labial palps 3-segmented, I with apical 1/2 projecting beyond margin of prementum and reaching apex of ligula; both with 1 apical seta; III longer than II.

Rostrum. Length 0.46-0.57 mm, anterior portion 1.5-2 × broader than long, rostrum/pronotum length ratio 0.49-0.56, rostrum length/width ratio 1.02-1.26; shape in cross section rectangular to square. Dorsal outline of rostrum sub-rectangular, posterior half of dorsal surface strongly rugose. Rostrum in lateral view sub-rectangular; basal half of dorsolateral margins very strongly converging anteriorly; apical margin with 2 large vibrissae. Nasal plate defined (sometimes weakly) by Y-shaped, impressed lines, slightly convex, weakly elevated from impressed lines, integument posteriorly covered with scales like those of rest of body, anteriorly with elliptical, white to beige colored scales. Margins of mandibular incision ventrally slightly curved, directed 30° outward dorsally in frontal view. Ventrolateral sulci usually weakly defined (in some specimens entirely obscure) except for endpoints, beginning as a notch dorsad of in sertion point of mandibles, continuing parallel to scrobe, and terminating in a fovea ventrad of anterior margin of eye. Dorsal surface of rostrum with short median sulcus running from fovea at posterior end of rostrum, nearly 1/2 × median length of nasal plate. Oral cavity with lateral margins feebly curved.

Antennae. Minute tooth formed by overhanging dorsal margin of scrobe anterior to margin of eye by 1/3 of length of eye. Club 3-3.5 × as long as wide.

Head. Eyes separated in dorsal view by 4-5 × their anterior-posterior length, set off from anterior prothoracic margin by 1/3 of their anterior-posterior length. Head between eyes rugose and slightly bulging, appearing nearly flat in some specimens.

Pronotum. Overall slightly wider than long, length/width ratio 0.80-0.91, sub-cylindrical to slightly globular; median sulcus absent. Anterior margin curved, posterior margin nearly straight. Pronotum in lateral view with setae that reach midpoint between base of seta and anterior margin. Anterolateral margin with a reduced tuft of 3 -4 ocular vibrissae present, emerging near ventral 1/2 of eye, becoming longer ventrally, stopping just above ventral margin of eye; vibrissae achieving a maximum length nearly 3/5 × anterior-posterior length of eye.

Scutellum. Not or only very minutely exposed.

Pleurites. Metepisternum covered by elytron near posterior 1/2 of metasternum; metepimeron entirely covered by elytron.

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

Legs. Profemur/pronotum length ratio 0.88-0.97; profemur with distal 1/5 produced ventrally as a short, sub-rectangular projection covering tibial joint. Protibia/profemur length ratio 0.86-0.90; mucro reduced to a very small laterally projected tooth. Metatibial apex with almond shaped convex ity ringed by 10 short, widely separated, spiniform setae.

Elytra. Length/width ratio 2.58-2.86; widest at anterior 1/4; anterior margins jointly 1.5-1.75 × wider than posterior margin of pronotum, curved posteriorly; humeri broadly rounded, not strongly projected; lateral margins gently curving after anterior 1/4, more strongly rounded and converging in posterior 1/2. Elytra in lateral view broadly convex, in some specimens planar; posterior declivity angled at nearly 55° to main body axis. Elytral striae usually broadly sculpted, occasionally appearing shallow, punctate; punctures faint beneath appressed scales, separated by 6-8 × their diameter; intervals elevated (more or less depending on specimen); scales overall generally appearing grey and drably colored.

Abdominal sterna. Ventrite III with posterior 3/4 abruptly elevated, posterior margin inconspicuous mesally, III and IV folding into a sulcus along lateral 1/3s of their length. Sternum VII mesally 1/2 × as long as wide, sub-trapezoidal; setae lengthening, and becoming more erect and setiform in posterior 1/3; anterior margin straight; posterior margin nearly straight, emarginate, and rimmed with short, posteriorly directed setae.

Tergum. Pygidium (tergum VIII) sub-cylindrical.

Sternum VIII. Anterior laminar edges each incurved forming a 135° angle with lateral margin; more sclerotized medially; posterior edge mesally incurved.

Ovipositor. Coxites 1.5 × longer than wide; styli 1/3 × maximum length of coxites, with 2-3 long setae near base.

Spermatheca. “U” -shaped; collum long, 1/2 × length of cornu, thickening posteriorly to attain a width of 1/2-3/4 × length of ramus, thence constricted to base of ramus, appearing (from “above”) like a wide bowl, collum sub-contiguous with, and angled at 90° to ramus; ramus bulbous and short, 1/2 × length of collum; corpus not swollen, of equal thickness to collum and cornu; cornu elongate, narrowed slightly apically, roughly equal to joint length of collum and corpus, inner angle between cornu and collum nearly 50°.

Male.

Not available or known.

Comments.

Members of this species exhibit varying degrees of elevation of the elytral intervals and sculpture of the pronotum.

Material examined.

Holotype (for Thylacites microps sec. Say [1831]) - female (only images seen; Fig. 20) " Curculio microsus ., Say., Missuri. Say./ typus [red]" (NHRS); holotype (for Minyomerus innocuus sec. Horn [1876]; junior synonym) - female (only images seen; Fig. 21) "[Pale green disk: United States - Nebraska, Kansas, North Dakota, South Dakota, Oklahoma, Colorado, Wyoming, Montana]/ 1824/ Minyomerus innocuus Horn/ Type 5158" (MCZ). Additional specimens examined: "Havre. Mon., Wickham, June 10-11/ compared with type, Minyomerus innocuus [this label appears on CWOB specimens]" (BYU: 1 female; CAS: 5 females; CWOB: 2 females); "CAN. Alta., 0.5 mi. W. Bindloss, VI-20-1967/ sagebrush, at night, A.G. Raske" (CWOB: 3 females); "Medicine Hat, Alta., 9-VI-1928/ F.S. Carr, Collector" (CAS: 2 females); "Medicine Hat, Alta., F.S. Carr" (BYU: 2 females); "Medicine Hat, Alb-5-28" (BYU: 3 females); "ALBERTA, Hwy. 3, Purple Springs, 2000', VI-18-1962/ compared with type, Minyomerus innocuus / Minyomerus innocuus Horn, Det. C.W. O’Brien, 1965" (CWOB: 1 female); "Chugwater, Wyo, 1955-VI-22/ 207/ Minyomerus innocuus , Det. C.W. O’Brien 1971" (CWOB: 1 female); "WY, Natrona Co., Sweetwater River, Hwy 220 nr. Independence Rock/ 5900', 42°29.6'N, 107°02.8'W, 2-vi-2012, S.M. Clark" (CWOB: 1 female); "COLO. Weld Co., 3 mi. N. Rockport, 5794' VII-22-1971, O’Briens & Marshall" (CWOB: 1 female).

Distribution.

This species has been found in the grassland and semi-arid regions of Alberta (Canada), Colorado, Kansas, Montana, New Mexico, and Wyoming (USA). It is likely that its range also includes other Great Plains states, such as North and South Dakota, Nebraska, Oklahoma, northern Texas, and Saskatchewan (Canada), based on similarity in habitat to the currently known distribution (Fig. 51).

Natural history.

Associated with sagebrush ( Artemisia [non-focal] sp.; Asteraceae [non-focal]). This species is putatively considered parthenogenetic, given the lack of male specimens across a range of sampling events.