Minyomerus rutellirostris [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 : 84-89

Taxon classification Animalia Coleoptera Curculionidae

Minyomerus rutellirostris [JF2015] Jansen & Franz sec. Jansen & Franz (2015) sp. n. Figs 46, 47, 48

Diagnosis.

Minyomerus rutellirostris [JF2015] can be readily differentiated from other congenerics by the separated procoxae and the size of the rostrum, which is as wide as the head, and distinctly square in dorsal view. In the males, the dilation of the rostrum is greatly exaggerated, and the lateral margins are flared. The ramus of the spermatheca is basally narrow, forming a stalk that tapers into an apical bulb. The aedeagus is elongate, narrowing towards the apexmore strongly in the region of the ostium.

Description - female.

Habitus. Length 4.47-5.29 mm, width 1.84-2.12 mm, length/width ratio 2.39-2.60, widest at anterior 1/4 of elytra. Integument orange-brown to black. Scales with variously interspersed colors ranging from slightly off-white to manila/tan to dark coffee brown, in some specimens appearing semi-translucent (in others opaque). Setae sub-recumbent, brown; with larger, more erect white setae interspersed throughout on even numbered elytral intervals, shorter setae arranged in rows on all elytral intervals.

Mandibles. Covered with opalescent scales, with 4 longer setae.

Maxillae. Cardo bifurcate at base with an inner angle of ca. 115°, inner (mesal) arm sub-equal in length to outer arm, inner arm of equal width to outer arm, arms of bifurcation equal in length to apically outcurved arm. Stipes sub-quadrate, nearly equilateral, roughly equal in length to inner arm of bifurcation of cardo, with a single lateral seta. Galeo-lacinial complexapically incurved (mesally); complexmembranous; setose in basal 2/3; dorsally with 8 apicomesal lacinial teeth; ventrally with 4 reduced lacinial teeth. Palpiger with a lateral patch of 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 2 apical setae; II with 1 mesoventral seta in addition to apical seta.

Labium. Prementum completely roughly hexagonal; apical margin straight, medially weakly or not projected (ligula reduced), weakly angulate; lateral margins slightly incurved; basal margin broadly arcuate. Labial palps 3-segmented, I with apexreaching margin of prementum; III slightly longer than II.

Rostrum. Length 0.57-0.77 mm, appearing distinctly flattened, anterior portion 2.5-3.0 × broader than long, rostrum/pronotum length ratio 0.46-0.53, rostrum length/width ratio 0.86-1.00; shape in cross section elongate rectangular. Dorsal outline of rostrum sub-rectangular, anterior half of dorsal surface slightly concave and weakly impressed, posterior half strongly rugose. Rostrum in lateral view rectangular; apical margin with 2 large vibrissae. Nasal plate defined by broad, Y-shaped concavities, convex, integument completely covered with scales similar to those of body. Margins of mandibular incision directed 30° outward dorsally in frontal view; ventrolateral sulci well defined, beginning as a sulcus dorsad of insertion point of mandibles, running parallel to scrobe, becoming fainter posteriorly and disappearing ventrally. Integument dorsad of sulcus expanded somewhat laterally. Dorsal surface of rostrum with median sulcus running from fovea at posterior end of anterior half rostrum to midpoint of pos terior half of rostrum; ventrolateral margins sub-parallel, in some specimens diverging. Rostrum ventrally lacking foveae in line with insertion point of mandibles. Oral cavity with lateral margins feebly curved.

Antennae. Dorsal margin of scrobe overhangs forming a small tooth ventrad of anterior margin of eye. Funicular antennomeres evenly progressing from elongate to broader than long; terminal segment lacking appressed scales, having instead a cover ing of apically-directed pubescence with interspersed sub-erect setae. Club 2.5-3.0 × as long as wide.

Head. Eyes separated in dorsal view by 4-5 × their anterior-posterior length, touching anterior prothoracic margin. Head without transverse post-ocular impression.

Pronotum. Length/width ratio 0.94-0.99, sub-cylindrical to globular; widest near anterior 1/3; median sulcus absent. Anterior margin broadly arcuate, lateral margins curved and widening into a bulge at anterior 1/3 of pronotum, thence straight to posterior margin, posterior margin straight. Pronotum in lateral view setae that reach beyond anterior margin; these setae becoming evenly longer laterally, nearly reaching into anterior 1/2 of eye at their maximum length. Anterolateral margin with a reduced tuft of post-ocular vibrissae present, consisting of 4-6 setae, emerging near ventral margin of eye; vibrissae achieving a maximum length 3/4 × anterior-posterior length of eye.

Pleurites. Metepisternum covered by elytron near posterior 1/5 of metasternum.

Abdominal sterna. Procoxal cavities positioned at midpoint, contiguous, prosternal process complete between coxae, slightly elevated. Mesocoxal cavities separated by distance 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 0.83-0.93; profemur with distal 1/5 produced ventrally as an oblique projection covering tibial joint. Protibia/profemur length ratio 0.87-0.94; mucro reduced to a small laterally projected tooth. Protarsus with tarsomere I 1.5 × as long as II; I and III similar in length, III equilateral. Metatibial apexwith almond shaped convex ity ringed by 11-13 short, widely separated, spiniform setae. Elytra. Length/width ratio 2.78-3.09; widest at anterior 1/4; anterior margins jointly 1.5 × 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 shallow depression at anterior 1/3; posterior declivity angled at nearly 70° to main body axis. Elytral striae defined; punctures visible, separated by 3-5 × their diameter; intervals elevated, with every other interval slightly more raised and with interspersed, sub-erect, white setae.

Abdominal sterna. Ventrite III elevated and set off from IV along lateral 1/4 of its length. Sternum VII mesally 3/5 × as long as wide; anterior margin weakly curved.

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

Sternum VIII. Anterior laminar edges each incurved forming a 110° angle with lateral margin; less sclerotized medially.

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

Spermatheca.?-shaped; collum short, apically with a small, hood-shaped projection angled at 90° to ramus, nearly equal in length to stalk of ramus and contiously aligned with curvature of bulb of ramus; collum sub-contiguous with, and angled at 90° to ramus; ramus basally elongate, forming a stalk, equal in length to collum, bulbous apically, 3 × thicker than stalk; corpus not swollen, of equal thickness to collum and cornu; cornu elongate, apically, gradually narrowed, strongly recurved in basal 1/4, straight along mesal 1/2, and curved near apical 1/4 such that apexis parallel to collum and corpus.

Male.

Similar to female, except where noted. Length 4.03-5.28 mm, width 1.36-1.80 mm, length/width ratio 2.70-3.17. Rostrum length 0.63-0.78 mm, rostrum/pronotum length ratio 0.49-0.55, rostrum length/width ratio 0.90-0.95. Pronotum length/width ratio 0.98-1.05. Profemur/pronotum length ratio 0.82-0.91, protibia/profemur length ratio 0.87-0.97. Elytra length/width ratio 3.01-3.21.

Rostrum. Rostrum similar to female, but generally more sculpted. Rostrum dorsally significantly more concave, emarginate, and with margins flared outwardly. Ventrolateral margins expanded laterally, each appearing as a semicircular projection beneath insertion point of scrobe. Scrobe channel less curved than female. Dorso-ventrally thinner than female.

Head. More sculpted than female, and with a more pronounced post-ocular impression. Thorax. More globular than female, but otherwise similar.

Elytra. In lateral view, dorsum flat, declivity significantly sharper, angled at 90° to main body axis. Intervals raised and all of uniform height and setation; lacking any of larger, more erect setae found on female.

Abdomen. Sternum VII 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. Posterior 1/4 constricted and depressed, with posterior margin flaring out and slightly projected dorsally.

Sternum VIII. Consisting of 2 sub-contiguous, sub-triangular sclerites; posterior margins widely angulate. Laminar alae of spiculum gastrale lateral with lateral margins basally parallel, apically outcurved.

Aedeagus. Length/width ratio 4.36-4.73; lateral margins converging posteriorly, somewhat more strongly converging in region of ostium. Width of pedon in lateral view becoming gradually narrower posteriorly in anterior 1/2, ventral margins in posterior 1/2 becoming straight towards apex, then abruptly curving to meet dorsal margins at a sharp apical point; apexacutely angulate. Flagellum apically with a small conical sclerite.

Etymology.

Named in reference to the dilated, concave rostrum of the male, which has the appearance of a shovel; rutellum = shovel, rostrum = beak or nose, rutellirostris = with a shovel-nose; Latin adjective ( Brown 1956).

Material examined.

Holotype - female "MEXICO: BAJA CALI–, FORNIA SUR: 3 km N., San Ignacio at km 77, 5-I-1979, Stop 79-33, Calif. Acad. Sci. Coll./ COLLECTORS:, David Weissman, Robert Love, Vincent Lee, Carolyn Mullinex" (CAS). Paratypes - same label information as female holotype (CAS: 1 female); "La Paz, L. Cal., X-7-41/ Ross & Bohart, Collectors" (CAS: 1 male); "San Pedro, L. Cal. X-7-41/ Ross & Bohart, Collectors/ Elissa sp. # 1" (CAS: 3 females, 5 males); "MEX: 12 mi. NW La Paz, Baja Calif. IX-18-67/ J. Chemsak, A. & M. Michelbache, Collectors" (EMEC: 1 female, 1 male); "MEX: Baja Sur, 8 mi. S. Mulege, X-7-1983 BLACKLIGHT, Faulkner & Andrews/ Minyomerus sp." (CSCA: 2 females); "MEX: Baja Calif. Sur, 34.4 mi. SE. Guerrero, Negro IX-22-1981, F. Andrews & D. Faulkner/ Collected in, Cereal bowl, Pit trap" (CSCA: 1 female); "Purissima, Oct. '73, Baja Calif., WM Mann. Minyomerus sp., DET. A T HOWDEN" (USNM: 1 male).

Distribution.

This species is found in Baja California Sur (Mexico) (Fig. 52).

Natural history.

Host plant unknown, though possibly creosote bush ( Larrea tridentata [DC.] Coville [non-focal]; Zygophyllaceae [non-focal]). No host plant associations have been documented.