Xylotrechus hovorei Swift, 2007

Barman, E. H., Michat, M. C., Alarie, Y. & Wolfe, G. W., 2007, Figs. 16 – 17. 16 in A Description of the First Instar of Hoperius planatus Fall, 1927 (Coleoptera: Dytiscidae: Colymbetinae: Colymbetini), with Phylogenetic Implications, The Coleopterists Bulletin 61 (2), pp. 287-291 : 287-291

Xylotrechus hovorei Swift , new species

( Fig. 1a )

Description. Male: Form moderate sized, cylindrical; integument testaceous; pubescence dense, appressed, white. Head with distinct frontal carinae on the

287

288 (Mannerheim), male, dorsal habitus.

median line, as long as wide, forming an elevated ridge at the median, giving it the shape of an acutely angled ‘‘V’’; densely pubescent throughout with mediumlength appressed white pubescence. Paraocular occipital patches on the vertex small, round, 1.5 mm in diameter, not attaining the antennal insertion or the frontal carinae, finely, densely punctate with no pubescence; peripheral areas of vertex moderately, very coarsely punctate; antennal tubercles elevated; labial palpi with apical segment not dilated, only slightly wider than previous segment; antennae short, with 11 antennomeres, only attaining the basal J of the elytra, antennomeres cylindrical, fourth the longest, antennal pubescence covering antennomeres two through five, remaining antennomeres ciliate. Pronotum as long as wide, outer angles oblique, evenly rounded, and widest behind midline, not as wide as humeri; surface coarsely, densely punctate, punctures not confluent, not forming irregular transverse ridges, and rounded with irregular edges; entire pronotum clothed in dense, white appressed pubescence, which obscures the disk; lateral pronotal calli lacking; scutellum densely pubescent, twice as wide as long, angles subquadrate. Elytra surface sparsely punctate with large, shallow punctures; densely pubescent throughout, with medium-length white hairs, smaller brownish pubescence underlying the overall white pubescence at the humeri; apical pubescence forming a single undulating line from the lateral margins to the suture; apices obliquely truncate, inner angle slightly rounded, outer angle rounded, both tapering to a short apical spine. Legs densely pubescent similar in vestiture to elytra and pronotum, moderately elongate, femora only moderately clavate; first metatarsomere equal in length to the remaining four combined; metafemora not attaining the elytral apices, meso- and metafemora sparsely rugulose on the dorsal side. Ventral surface densely pubescent as in pronotum and elytra; prosternum flat, apex acute, coxae protruding beyond the prosternal process; meta- and metepisternum flat, with oblique ‘‘V’’ shaped impressions; abdomen with ventrites one through three with narrow dark band at apical J. Length: 7.6–9.8 mm.

Female: similar to male, pronotum with more rounded angles, widest at middle, lateral punctures not as dense; head without paraocular occipital patches, antennae attaining only 1/8 the elytra. Meta- and mesofemora not as clavate. Elytral apices truncate and only feebly spined, pygidium as long as broad, with dense, white, appressed pubescence. Length: 7.2–8.4 mm.

Type Material. Holotype: male, from U.S.A., California, San Bernardino County, Mount Baldy Road , ex. bark of live Alnus rhombifolia , emerged 13 June 1983, F. T. Hovore ( USNM) . Allotype: female, same locality as holotype, but emerged July 1983, F. T. Hovore ( USNM) . Paratypes: two females, same data as holotype ( EMEC) ; one male from U.S.A., California, Ventura County, Wheeler Gorge , ex. bark of live Alnus rhombifolia , emerged 16 March 1972, F. T . Hovore ( CASC) ; two males, one female from U.S.A., California, Los Angeles County, 4.7 km west of Big Pines, upper Mescal Creek , 1598 m, 34 ° 24 9 26.16 0 N, 117 ° 44 9 54.05 0 W, ex. bark of live Alnus rhombifolia , emerged 12 April 1998, I. Swift ( LACM) ; one female from U.S.A., California, Los Angeles County, Littlerock Creek , 12 August 1967, B.S. Cheary ( UCRC) ; 6 females from U.S.A., CA , Ventura County, Wheeler Springs , 04–21 June 1976, J. Cope ( JCPC) ; one male, from U.S.A., CA , Los Angeles County, Tanbark Flat , 29 June 1950, H.N. Yokoyama ( JCPC) ; one male from U.S.A., CA , San Diego County, Mt Laguna , 06 August 1950, D. Cox ( JCPC); and one male from U.S.A., CA , San Bernardino County, Mouth of Deep Creek , 29 June 1968, H.I. Schlinger ( JCPC) .

Diagnosis. Xylotreches hovorei will key to X. nauticus (Mannerheim) ( Fig. 1b ) in both Hopping (1932, 1937) and Linsley (1964), however it can be distinguished by the following characters: dense uniform integumental pubescence that forms only one apical undulating band on the elytra; unicolorous elytral integument; presence of dark apical bands on the first through third ventrite; frontal carinae as wide as long; smaller paraocular occipital patches (1.5 mm in diameter); pronotum as wide as long; coarsely, densely punctate pronotum lacking irregular transverse ridges; the first metatarsomere, which is equal in length to the remaining four tarsomeres combined; and metafemora not attaining the elytral apices in male.

Xylotrechus hovorei is similar to X. anosus (Say) in overall elytral pubescence pattern, however, X. anosus differs in having a bicolored elytral integument with eburneous markings beneath dense patches of pubescence, more rounded apices, less dense and uniform integumental pubescence throughout which does not obscure the pronotal disk, and a frontal carina that is longer than wide. Xylotrechus anosus emotus Brown , has been assigned to populations of this species in the western US, including northern California, where the larval host is predominately Salix .

Xylotrechus hovorei is similar to X. integer (Haldeman) in its unicolorous elytral integument and spined apices, however, it can be distinguished by the following 290 characters: the length of the first tarsomere, which is greater than 1.5 X the remaining four tarsomeres in X. integer ; the frontal carina, which is longer than broad in X. integer ; the pubescence of the pronotum, which in X. integer forms dense patches at the lateral margins, leaving the medial ridge unobscured; and the first four antennomeres, which lack dense, appressed, pale pubescence of X. hovorei . The typical pattern of elytral pubescence in X. integer , which can vary geographically, is not present in X. hovorei . Additionally, the two species are completely allopatric, and the larval hosts of X. integer include various species of conifers.

Biology. Larvae of X. hovorei feed beneath the senescent bark of mature Alnus rhombifolia Nutt. Galleries meander along the cambium at varying depths, and pupation occurs in the thickened portions of the bark. Typically, the north-facing portion of the tree is favored, at a height of two to three feet above the ground. Old emergence holes are conspicuous on trees that are even moderately infested. The larval development period is one year in all material reared for this study.

Emergence data is entirely of laboratory-reared specimens from bark of the host plant, and the natural adult activity period is unknown, however, fresh emergence holes were observed in April and May in several years.

Although field studies have focused on other geographic areas in California, X. hovorei and its putative emergence holes have only been observed in the mountains of southern California. The habitat of this species is typical of montane riparian systems of the region; dominant species include: Quercus chrysolepis Liebm. , Acer macrophyllum Pursh , Salix lasiolepis Benth. , and Pinus jeffreyi Grev. & Balf. Due to the damage inflicted upon the host trees by collecting the bark for rearing, a relatively limited number of samples were collected, X. hovorei is probably more common and widespread than indicated by the type series.

Etymology. This species is dedicated to the late Frank Hovore (1945–2006), mentor and friend, who brought my attention to this new species, and for his numerous contributions to cerambycid taxonomy throughout the New World.

Figures

Fig. 1a, Xylotrechus hovorei Swift, new species, male, dorsal habitus. Fig. 1b, X. nauticus