Euwallacea fornicatus (Eichhoff)

Kirkendall, Lawrence R. & Ødegaard, Frode, 2007, Ongoing invasions of old-growth tropical forests: establishment of three incestuous beetle species in southern Central America (Curculionidae: Scolytinae), Zootaxa 1588, pp. 53-62 : 58-59

Euwallacea fornicatus (Eichhoff)

( Fig. 1 e–h)

Records. Recently discovered in North America ( Rabaglia et al., 2006; Thomas, 2005); one previous record for Neotropics, a single specimen from an unidentified branch in the Panama Canal Zone in July 1979 (Wood 1980). COSTA RICA, Heredia, La Selva Biological Station 10o 26’ N, 84o 01’ W, 50–150 m elevation, 8 April 1982 (1) & 7 April 1983 (1), H. A. Hespenheide; La Selva, 12 July 1996 (1), 2 cm branch of Protium panamense , and 31 July 1997, 3 cm branch of Cedrela odorata (1), L. Kirkendall; La Selva, Project ALAS Malaise traps in old-growth forest emptied on 15 Feb. 1993 (1), 1 May 1993 (1), 2 May 1993 (1), 1 July 1993 (1), 15 Feb. 1994 (1), one in secondary growth forest, 2 April 1993 (2). The Malaise traps in old-growth forest are within 500 m of more disturbed habitats with the exception of a trap (M/08) which is ca 1100 m inside oldgrowth forest.

PANAMA, multiple collections from old-growth forest in Prov. Col\n, San Lorenzo Protected Area: 1. Feb. 2002, beating dead branches of Brosimum utile in the understory, F. Ødegaard (1); 1–13 Oct. 2003, flight intercept trap at 14 m height, R. Didham & L Fagan (1); 11–15 Oct. 2003, sticky trap, Y. Basset (1); 31 May 2004, beating dead branches of Tocoyena pittieri (Rubiaceae) , F. Ødegaard (1).

Diagnosis. This species was identified by direct comparison with authenticated specimens in The Natural History Museum (London). This species was sorted for several years as an unidentified species in the endemic genus Theoborus , in the ALAS collections. Though Euwallacea and Theoborus are not closely related ( Jordal, 2002), these taxa are quite similar; E. fornicatus and most described and undescribed Theoborus from Central America have a carinate posterolateral declivital margin which extends from interstriae 7 or striae 7 on the disc ( Fig. 1 e, h), and E. fornicatus and Theoborus have similar body proportions, a suture on the antennal club continued on the posterior face ( Fig. 1 g, arrow), and a crenulate margin of the pronotum. This species can be identified using the key to Xyleborus in Wood (1982). However, it could easily key to Theoborus in that work (op. cit., p. 69), if one does not have great familiarity with antennal club structure in this group, though it does not to key any species in that genus. Euwallacea fornicatus can be distinguished from native Theoborus species of Central America by a combination of size, shape, and details of the elytra ( Wood, 1982).

Comments. The single Panama collection (Wood 1980) remained the only New World record until North American specimens were collected from the ornamental tree Delonix regia (Fabaceae) in Dade County, Florida in 2002, and in 2003 in Los Angeles County, California, from four different hosts ( Acer negundo, Alnus rubra, Platanus racemosa, and Robinia pseudoacacia ); since then, repeated collections in Dade and Broward counties suggest that E. fornicatus is solidly established in the southern tip of Florida ( Haack, 2006; Thomas, 2005).

This Old World species is notorious as a pest of tea (“the shot-hole borer of tea”), in Sri Lanka and southern India, Borneo, and Java; elsewhere, it is a pest in plantations, recently reforested plots, and nurseries ( Browne, 1961; CAB International, 2005a; Kalshoven, 1958). Most attacks are to twigs and small branches or stems. Euwallacea fornicatus seems to be much less abundant than the previously discussed species, with very few specimens yet known despite the intensive sampling of wood-boring insects at the collection sites. As with X. crassiusculus , we cannot say if the disjunct distribution (northeast Costa Rica –central Panama) reflects lack of sampling in the intervening region or separate populations resulting from multiple introductions.

Wood (2007) reports a series of specimens from Manaus, Brasil, but with no collection data.

Figures

FIGURE 1. Invasive Asian xyleborine ambrosia beetles in Central American forests. (a – c) Xylosandrus crassiusculus: the shape (a), size (2.2 – 2.5 mm), and dull declivity with dense long setae and dense, scattered granules (c) are characteristic. (d) Xyleborinus exiguus: note the plain, convex declivity with a distinctive border of large teeth at the apex. (e – h) Euwallacea fornicatus: arrow (g) indicates suture on the posterior face of the antennal club (upper antenna in figure shows anterior face).