Minyomerus gravivultus [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 : 74-76

Taxon classification Animalia Coleoptera Curculionidae

Minyomerus gravivultus [JF2015] Jansen & Franz sec. Jansen & Franz (2015) sp. n. Figs 41, 42

Diagnosis.

Minyomerus gravivultus [JF2015] can be distinguished from other congenerics by a combination of features, and is similar to Minyomerus languidus [JF2015] in general appearance. The frons is protuberant in this species, and the nasal plate is covered with scales that have a strongly opalescent reflectance. The elytra are lightly sculpted. The ocular vibrissae are as long as the eye, but reduced in number. The oral cavity has weakly curved lateral margins; the posterior margin is at least as long as the lateral margins. The genae are not impressed with a strong ventrolateral suture. The spermatheca has a bulbous, basally tapered ramus. Additionally, the lamina of the spiculum gastrale is mesally membranous between the laminar arms. The aedeagus is acute and evenly curved.

Description - female.

Habitus. Length 3.74-4.15 mm, width 1.53-1.64 mm, length/width ratio 2.45-2.53, widest near midpoint 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 opalescent or with metallic reflections. Setae brown, becoming longer, white, and more erect on humeri and venter.

Mandibles. Covered with opalescent scales, each with 2 pairs of long setae.

Maxillae. Cardo bifurcate at base with an inner angle of ca. 105°, 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, glabrous. Stipes sub-quadrate, 1.5-2 × longer than wide, roughly equal in length to inner arm of bifurcation of cardo, with 1 short, lateral seta. Galeo-lacinial complexapically incurved (mesally); complexmembranous; setose in basal half; dorsally with 7 apicomesal lacinial teeth; ventrally with 5 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, with 2 apical setae.

Labium. Prementum completely roughly pentagonal; apical margins feebly curved, angulate; lateral margins curved; basal margin arcuate; each lateral region with 1 or 2 long setae. Labial palps 3-segmented, I with apexjust projecting beyond margin of prementum, not reaching apexof ligula; III slightly longer than II.

Rostrum. Length 0.56-0.61 mm, anterior portion 1.5-2 × broader than long, rostrum/pronotum length ratio 0.57-0.65, rostrum length/width ratio 1.33-1.39. Dorsal outline of rostrum sub-rectangular, anterior half of dorsal surface strongly impressed, posterior half strongly rugose. Rostrum in lateral view trapezoidal; anterior half of dorsolateral margins somewhat diverging; apical margin with 2 large vibrissae. Nasal plate strongly defined by Y-shaped, impressed lines, medially convex; integument completely covered with strongly opalescent scales. Margins of mandibular incision curved, directed 25° outward dorsally in frontal view, bounded by whitish scales, similar to rest of body; ventrolateral sulci somewhat defined, beginning as a broad, shallow sulcus dorsad of insertion point of mandibles, running parallel to scrobe, becoming fainter posteriorly and disappearing into a fovea ventrally. Dorsal surface of rostrum with median sulcus running from fovea at posterior end of anterior half rostrum to midpoint of posterior half of rostrum; ventrolateral margins slightly converging. Rostrum ventrally lacking foveae in line with insertion point of mandibles. Oral cavity with lateral margins curved.

Antennae. Dorsal margin of scrobe overhangs forming a small tooth antero-ventrad of anterior marginof eye. Funicular antennomeres evenly progressing from elongate to broader than long; terminal segment lacking appressed scales, having instead a covering of apically-directed pubescence with interspersed sub-erect setae. Club similar in length to funicular antennomeres III-VII, nearly 2.5 × as long as wide.

Head. Eyes strongly impressed; eyes separated in dorsal view by 4-5 × their anterior-posterior length, narrowly separated from anterior prothoracic margin.

Pronotum. Length/width ratio 0.91-1.01, sub-cylindrical to conical; widest near anterior 1/4. Anterior margin arcuate, lateral margins feebly curved and widening into a slight bulge near anterior 1/3 of pronotum, thence straight to posterior margin, posterior margin straight. Pronotum in lateral view with setae that reach beyond anterior margin; these setae becoming evenly longer laterally, reaching posterior margin of eye at their maximum length. Anterolateral margin with a reduced tuft of post-ocular vibrissae present, consisting of 3-5 setae, emerging slightly above ventral margin of eye, becoming gradually, evenly longer ventrally, stopping just beneath ventral margin of eye; vibrissae achieving a maximum length nearly equal to anterior-posterior length of eye.

Pleurites. Metepisternum covered by elytron near posterior 7/8 of metasternum.

Thoracic sterna. Mesocoxal cavities separated by distance1/3 × width of mesocoxal cavity. Metasternum without apprent transverse sulcus; metacoxal cavities widely separated by 1.5-2 × their width.

Legs. Profemur/pronotum length ratio 0.93-1.02; proximal 5/6 of profemur gradually widening, then abruptly constricted with distal 1/6 produced ventrally as a nearly square projection covering tibial joint; condyle of tibial articulation occupying 2/3 of distal surface and 1/6 length of femur. Protibia/profemur length ratio 0.88-0.99; mucro reduced to a small, laterally projected tooth. Protarsus with tarsomeres I and II jointly similar in length to V. Metatibial apexwith almond shaped convex ity ringed by 9-11 short, widely separated, spiniform setae.

Elytra. Length/width ratio 3.00-6.80; widest near midpoint; anterior margins jointly 1.5-2 × 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 60° to main body axis. Elytral striae well defined, punctate; punctures visible in some specimens, separated by 3-5 × their diameter.

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-cylindrical; medial 1/3 of anterior 1/2 of pygidium less sclerotized.

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

Ovipositor. Coxites slightly sclerotized, in dorsal view 2 × as long as broad; styli 3/4 × length of coxites, with 3 long setae near base.

Spermatheca. Comma-shaped; collum short, sub-contiguous with, and angled at 90° to ramus; ramus bulbous, 2 × width of cornu; corpus swollen, 1.5 × thickness of cornu; cornu elongate, apically gradually narrowed, strongly recurved with an inner angle of 90° in basal 1/4, nearly sraight along mesal 1/2, and incurved 90° near apical 1/4 such that apexis sub-parallel to hood-shaped projection of collum.

Male.

Similar to female, except where noted.

Abdomen. Sternum VII slightly more broadly arcuate posteriorly, 3/5 as long as wide. Tergum VII with posterior margin straight. Pygidium (tergum VIII) with posterior 1/2 punctate; anterior 1/2 rugose. Posterior 1/5 constricted and depressed, with posterior margin flaring out and slightly projected dorsally.

Sternum VIII. Consisting of 2 subcontiguous, sub-triangular sclerites; posterior margins widely angulate. Laminar alae located on lateral 1/4s of posterior margin. Mesal 1/2 with a short, sub-trapezoidal projection.

Aedeagus. Length/width ratio 3.41. Pedon in lateral view with ventral margins curving to meet dorsal margins at a sharp apical point; apexacutely angulate. Flagellum with a small tortuous, recurved, ampullate sclerite, situated in anterior portion of flagellum.

Etymology.

Named in reference to the enlarged supraorbital ridges, which give the impression of a furrowed brow; gravis = heavy or serious, vultus = countenance or face, gravivultus = serious countenance; Latin noun in apposition ( Brown 1956).

Material examined.

Holotype - female "MEXICO: Baja California, 5.5 mi. E El Arco, IV-15-1987, F. Andrews & A. Glibert" (CSCA). Paratypes, same label information as female holotype (CSCA: 3 females); "MEXICO: Baja California Sur, 1.9 mi. SW El Arco, IV-16-1987, F. Andrews & A. Gilbert" (CSCA: 1 male).

Distribution.

This species has been found in Baja California, near the border of Baja California Sur (Mexico) (Fig. 52).

Natural history.

Host plant associations remain unknown, though possibly on creosote bush ( Larrea tridentata [DC.] Coville [non-focal]; Zygophyllaceae [non-focal]).