Minyomerus bulbifrons [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 : 65-68

Taxon classification Animalia Coleoptera Curculionidae

Minyomerus bulbifrons [JF2015] Jansen & Franz sec. Jansen & Franz (2015) sp. n. Figs 36, 37

Diagnosis.

Minyomerus bulbifrons [JF2015] is readily differentiated from other congenerics by the heavily protuberant frons (which can extend up to 3 × the length of the eye from the anterior margin of the eye), strongly impressed nasal plate, and punctate elytra. The elytra are angled at their point of contact with the pronotum such that they appear confluent with the posterior margin of the pronotum. The elytral setae are arranged in regular rows, and are small, subrecumbent, and brown. The spermatheca is distinct, with the ramus basally tapered, 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 counterclockwise and is as long as the aedeagal pedon.

Description - female.

Habitus. Length 3.67-4.10 mm, width 1.41-1.60 mm, length/width ratio 2.49-2.61, widest at anterior 1/5 of elytra. Integument dark reddish-brown to black. Scales slightly off-white to manila/tan to beige, in some specimens appearing semi-translucent (in others opaque) or metallic; occasionally monotonic and off-white, but usually with interspersed colors forming small maculae, bands and other variously scattered patterns; scales generally off-white ventrally, including rows of setae. Setae minute, sub-recumbent, of equal length throughout.

Mandibles. Covered with whitish scales, with 2-3 longer setae, and 3-5 shorter interspersed setae.

Maxillae. Cardo bifurcate at base with an inner angle of ca. 105°, arms roughly equal in length and width, arms of bifurcation equal in length to apically outcurved arm. Stipes nearly square, equilateral, roughly equal in length to inner arm of bifurcation of cardo, with a single lateral seta. Galeo-lacinial complexmembranous and setose in posterior 2/3, sclerotized and somewhat emarginate anteriorly; dorsally with 9 apicomesal lacinial teeth; ventrally with 4 reduced lacinial teeth. Palpiger with a transverse row of setae; anterior 1/3 membranous, posteriorly sclerotized.

Maxillary palps. Palpomere I with apical end facing mesally and forming a 30° angle with base, I with 2 apical setae, II with 3 dorsal, 1 apical, and 1 mesoventral setae.

Labium. Prementum roughly pentagonal; apical margins sinuate, ligula broadly rounded, lateral margins broadly sinuate, posterior margin curved. Labial palps 3-segmented, I with apical 1/3 projecting beyond margin of prementum and apexof ligula.

Rostrum. Length 0.53-0.59 mm, anterior portion ca. 2.5 × broader than long, rostrum/pronotum length ratio 0.60-0.75, rostrum length/width ratio 1.00-1.14. Dorsal outline of rostrum square, anterior half of dorsal surface mesally concave, posterior half strongly convex and punctate. Rostrum in lateral view nearly square; anterior half dorsolateral margins slightly diverging; apical margin with 2 groups of 3 large vibrissae, each group inserted just laterad of apexof each sinuation. Nasal plate defined by V-shaped, impressed lines, concave, integument covered with white scales. Margins of mandibular incision only very slightly diverging dorsally in frontal view. Ventrolateral sulci strongly defined as a deep notch dorsad of insertion point of mandibles.

Antennae. Dorsal margin of scrobe overhanging slightly and forming a minute tooth, anterior to margin of eye by 1/3 of length of eye. Club 2.5-3.0 × as long as wide.

Head. Eyes separated in dorsal view by 5-6 × their anterior-posterior length, set off from anterior prothoracic margin by 2/5-1/2 of their anterior-posterior length. Head between eyes punctate and strongly protuberant.

Pronotum. Wider than long, length/width ratio 0.75-0.83. Anterior margin slightly curved and somewhat produced dorsally; anterior constriction subtle in some specimens, posterior margin incurved. 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 × anterior-posterior length of eye.

Pleurites. Metepisternum covered by elytron near posterior 1/8 of metasternum.

Thoracic sterna. Mesocoxal cavities separated by 1/6 × width of mesocoxal cavity. Metasternum with a somewhat obscure transverse sulcus; metacoxal cavities separated by 2-2.5 × 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 0.97-1.061; profemur with distal 1/5 produced ventrally as an obliquely rounded projection covering tibial joint. Protibia/profemur length ratio 0.91-0.99; protibia moderately stout; mucro present as a laterally projected tooth equal in length and nearly 2 × as wide as nearby setae, triangular. Protarsus with tarsomeres I-II jointly similar in length to V. Metatibial apexwith almond shaped convex ity ringed by 9-10 short, spiniform setae.

Elytra. Length/width ratio 3.16-3.46; widest at anterior 1/5; anterior margins jointly 1.5-1.75 × wider than posterior margin of pronotum; lateral margins slightly converging after anterior 1/5, more strongly rounded and converging in posterior 1/3. Posterior declivity broadly arcuate dorsally, slightly inflected thereafter, angled at 45-50° to main body axis. Punctures distinct, separated by 3-5 × their diameter; intervals elevated and with small inapparent puntures, separated by 10-15 × their diameter; scales occasionally monotonic off-white.

Abdominal sterna. Ventrite III elevated and set off from IV along lateral 1/3 of its length. Sternum VII mesally 1/2-3/5 as long as wide; anterior margin straight. Tergum. Pygidium (tergum VIII) entirely sub-cylindrical; medial 1/3 of anterior 1/2 of pygidium less sclerotized.

Sternum VIII. Anterior laminar edges each incurved forming a 105° angle with lateral margin, sclerotized region less sclerotized medially. Ovipositor. Coxites 2/3 as broad as long in dorsal view.

Spermatheca. Comma-shaped; collum short, apically with a large, hood-shaped projection perpendicular to ramus, nearly equal in length and contiously aligned with curvature of bulb of ramus and ante-apically with a long, perpendicular, cylindrical projection, nearly equal in length to collum and 1/2 length of ramus; collum short, cylindrical, sub-contiguous with, and angled at 90° to ramus; ramus elongate, bulbous, equal in thickness to corpus; corpus swollen, slightly thicker than collum, 1.5 × thickness of cornu; cornu elongate, apically, gradually narrowed, strongly recurved in basal 1/2, forming an inner angle of ca. 60° to collum and corpus, abruptly bent outward ca. 30°, then incurved.

Male.

Similar to female, except where noted. Length 3.26-3.44 mm, width 1.20-1.28 mm, length/width ratio 2.59-2.78. Rostrum length 0.46-0.56 mm, rostrum/pronotum length ratio 0.61-0.78, rostrum length/width ratio 0.95-1.08. Pronotum length/width ratio 0.72-0.83. Profemur/pronotum length ratio 1.05-1.30, protibia/profemur length ratio 0.92-0.96. Elytra length/width ratio 3.24-3.59.

Elytra. Elytral declivity slightly more angulate, forming a 55-60° angle to main body axis, but otherwise as female.

Abdomen. Sternum VII 2/5-1/2 × as long as wide. Pygidium (tergum VIII) with posterior 2/3 punctate; anterior 1/3 rugose.

Aedeagus. Length/width ratio 2.83-3.29. Flagellum with a large, narrowly elongate, tortuous, spiriform sclerite, sclerite anteriorly gradually widened and more sclerotized, constricted slightly in anterior 1/8 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.

Etymology.

Named in reference to the greatly expanded and protuberant frons; bulbus = bulbous, frons = forehead; bulbifrons = with a bulbous forehead; Latin invariable adjective ( Brown 1956).

Material examined.

Holotype - female "Gila Bend, Ariz. 10m N, July 22, 1924/ EP Van Duzee, Collector" (CAS). Paratypes, same label information as female holotype (CAS: 22 females, 19 males); "Cal, Providence Mts. S. Bdo. Co., Bonanaza King Mine, 4-23-1966/ on Larrea tridentata [non-focal], at night, C.W. O’Brien” (CWOB: 1 male); "ARIZONA, Ehrenberg, V-21-1939, EP Van Duzee/ " Elissa " DET. A.T. HOWDEN" (CAS: 1 female); "USA: Ariz.: Yuma Co., 12 mi. W. Dateland, Hwy 80, 13-II-1970, P.H. Arnaud, Jr./ Swept from flowers, Encilia farinosa A. Gray [non-focal]" (CAS: 1 female); "Potholes Cal., Imperial Co., April 10, 1923/ EP Van Duzee, Colletor/ ex. Larria mexicana [non-focal]" (CAS: 1 female, 1 male); "NEVADA, Clark Co., 5 mi. NE Jct I-15 & Carp Rd., VIII-27-1977, Andrew H. Barnum" (BYU: 1 female, 2 males); "ARIZ., Mohave Co., Mt. Trumbull Road, 18 mi. S Utah Line, VIII-28-1977, Andrew H. Barnum" (BYU: 1 female); "UTAH, Washington Co., Beaver Dam Mts. at Ariz. Line, VII-16-1973, A. H. BARNUM" (BYU: 1 female); "UT: Washington Co., Beaver Dam Well, Beaver Dam Wash, 28 Sept 1985, Mower & Nelson" (BYU: 1 female); "Telegraph Pass, Yuma, Ariz, 2-18-1936/ A. T. McClay, Collector/ Elissa constricta ?" (UCDC: 5 females, 3 males).

Distribution.

This species has been found in the Mojave and Sonoran Desert regions of Arizona, California, Nevada, and Utah (USA). It is likely that this species is also present in Sonora and Baja California (Mexico), based on the availability and proximity of similar habitat (Fig. 52).

Natural history.

Associated with creosote bush ( Larrea tridentata [DC.] Coville [non-focal]; Zygophyllaceae [non-focal]) and brittlebush ( Encilia farinosa Torr. & A. Gray [non-focal]; Asteraceae [non-focal]).