Metamasius planatus Anderson

Anderson, Robert S., 2013, Two new species of Dryophthorinae in the genera Metamasius and Melchus from the Lesser Antilles (Coleoptera: Curculionidae), Zootaxa 3750 (4), pp. 396-400 : 396-398

Metamasius planatus Anderson , new species

( Figures 1–4 )

Identification.—Specimens of this species are easily recognizable by their relatively flat profile and presence of dense, very fine, golden micropilosity covering most of the dorsal surface, especially the elytra and pronotum. This micropilosity is dense throughout the length of the elytral sutural interval and in the basal portions of intervals 3, 5 and 7 giving them the appearance of being wider than adjacent intervals. Four other species of Metamasius occur on Dominica; M. hemipterus (L.), M. liratus (Gyllenhal) , M. maurus (Gyllenhal) and M. quadrisignatus (Gyllenhal) (O’Brien and Turnbow 2011).

Description.— Male, 11.2-12.1 mm long; 3.9-4.3 mm wide. Female, 10.4-12.9 mm long; 3.5-4.7 mm wide. Color mostly black dorsally and ventrally; elytra dark reddish brown to various extent in basal one-half. Body flat in profile, depth slightly more than one-half width at midlength; covered variously with dense, very fine, golden micropilosity. Rostrum about one-half length of pronotum; markedly curved, compressed laterally, impunctate; basal margin crenulate (male) or not (female), with short, rounded, ventrally directed swelling immediately anterior to point of antennal insertion, basal expanded area moderate, about one-fourth to one-fifth total rostral length, dorsally carinate medially in basal one-third (more so in male), ventrally with peduncle flat, bilamellate anteriorly. Scrobe with posterior margin separated from anterior margin of eyes by about 2-3 times width of base of scape. Antennal scape about one-half length of rostrum; club robust, oval; apical pilose part large, about two-fifths length of entire club. Pronotum with length greater than width (6/5), with lateral margins subparallel in basal one-half, convergent subapically, markedly tubulate to apex; sparsely, shallowly punctate throughout; disc flat, very slightly impressed at middle base, surface covered with very dense, very fine golden micropilosity that obscures most surface features. Elytra about 1.5 times length of pronotum; sutural (throughout length) and alternate intervals 3, 5, 7 (in basal one-third to one-half) covered with very dense, very fine golden micropilosity that obscures most surface features (and makes intervals appear wider than adjacent ones), intervals flat; striae with small, shallow punctures. Scutellar shield elongate “U” shaped, variously micropilose in some specimens, length 2.5 times width at base, anterior margin straight. Pygidium slightly convex, oblique in orientation, coarsely deeply regularly punctate, punctures obscured towards posterior margin by dense micropilosity; apical margin with fringe of short, fine setae. Ventrally with forecoxae very narrowly separated by about one-third width of coxa, forecoxae with inner faces with large golden pilose patch; prosternum moderately densely, regularly punctate, flat; tubulate anterior extension of pronotum crenulate. Lateral portions of metasternum and ventrites 1-5 moderately densely punctate; punctures larger laterally on ventrites 2-5; middle of metasternum and ventrites 2-4 virtually impunctate, shining; first ventrite regularly punctate throughout; last ventrite flat, punctate throughout except for small median basal impunctate patch. Legs short, punctate; femora clavate, hind femur reaching apex of ventrite 4; tibiae multicarinate longitudinally, inner margins slightly sinuate and each with two inner fringes of short stout hairs. Tarsi relatively long and slender, length almost as long as that of tibia, third article broadly expanded laterally, ventrally with distinct pilose pads.

Sexual dimorphism.—Males have a slightly more sculptured and distinctly carinate rostrum and have the ventral surface of the rostrum crenulate throughout its length. Sexual dimorphism in characters seen in other Metamasius species such as presence or absence of tufts of setae on legs or on abdominal ventrite 5 are not evident.

Material examined.—Male HOLOTYPE labelled “ Dominica: Morne Plat Pays, 10.xii.1964, P.J. Spangler, in base Euterpe globosa fronds (USNM). Paratypes, 14 males, 9 females. 3 males, same data as holotype (USNM, CMNC). 4 males, 3 females, Freshwater Lake, 16.ix.1964, T.J. Spilman (USNM, CMNC). 6 males, 2 females, Freshwater Lake, 5.ix.1964, T.J. Spilman (USNM, CMNC). 1 male, 1 female, Fresh Pond, 2800’, 28.xii.1964, R.T. Bell (CMNC). 2 females, 1.0 mi.W. Pont Casse, 18.ix.1964, T.J. Spilman (USNM). 1 female, 1.7 mi.E. Pont Casse, 12.iii.1965, W.W. Wirth, light trap (USNM). 1 female, Freshwater Lake, ca. 2400’, 32, vi.2004, C.W. & L. O’Brien (CWOB). 2 males, 1 female, Freshwater Lake, ca. 2600’, 2.viii.1986, C.W. & L. O’Brien (CWOB). 4 males, 2 females, Dublanc, 5 mi. E., 18-20.viii.1986, on cut palms under base fronds, C.W. & L. O’Brien (CMNC, CWOB). 6 males, 5 females, Salisbury, 4 mi. E., 19.viii.1986, on palms under base fronds, C.W. & L. O’Brien (CMNC, CWOB). 2 males, 2 females, Salisbury, 6 mi. E., Morne Apion, 2500’, 19.viii.1986, on palms under base fronds, C.W. & L. O’Brien (CWOB, WIBF).

Distribution.— Dominica.

Natural history.— Label data indicates some specimens were collected from the bases of Euterpe globosa fronds and on palms under the bases of the fronds.

Derivation of specific name.—This species is named ‘planatus’ after the flat lateral profile of the adults.

Figures

FIGURES 1 – 4. Metamasius planatus. 1. Dorsal habitus, female. 2. Lateral habitus, female. 3. Antenna, female. 4. Pygydium, female.