Occurrence of Xyleborus Bispinatus (Coleoptera: Curculionidae: Scolytinae) Eichhoff in Southern Florida

Zootaxa 3669 (1): 096–100 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2013 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3669.1.10 http://zoobank.org/urn:lsid:zoobank.org:pub:3A31B3A7-25E5-4328-958B-EF86B7FBDA1B Occurrence of Xyleborus bispinatus (Coleoptera: Curculionidae: Scolytinae) Eichhoff in southern Florida

THOMAS H. ATKINSON1, DANIEL CARRILLO2, RITA E. DUNCAN2 & JORGE E. PEÑA2 1University of Texas Insect Collection, 3002 Lake Austin Blvd., Austin, TX 78703, U.S.A. E-mail: [email protected] 2Tropical Research and Education Center, University of Florida, 18905 SW 280th St., Homestead, FL 33031, U.S.A. E-mail: [email protected]

Abstract

Xyleborus bispinatus Eichhoff is reported from Florida for the first time. It was previously unrecognized and not distinguished from Xyleborus ferrugineus (F.). There is no reason to believe at this point that it represents an introduction. Rather it is one of a group of widely distributed Neotropical species that are also found in southern Florida. Characters are discussed to allow it to be distinguished from X. ferrugineus and X. impressus Eichhoff.

Xyleborus ferrugineus (F.), presumably of New World origin, is currently found in all tropical and warm temperate areas of the world (Wood 1982; Wood & Bright 1992). Consequently it has been named many times from different areas. Wood & Bright (1992) list 18 synonyms. A closer examination of the variability of characters within regions has shown that several of these synonymies were unjustified. Rabaglia (2005) restored X. impressus Eichhoff from synonymy, a species that co-occurs with X. ferrugineus over most of eastern North America but has not been found elsewhere. Kirkendall & Jordal (2006) resurrected X. bispinatus Eichhoff which is distributed from Belize through Brazil. In studies of the ambrosia beetle complex associated with avocado, Persea americana, in southern Florida (Carrillo et al. 2012), it became apparent that 2 distinct, and readily distinguishable forms of “Xyleborus ferrugineus” were present in samples, in some cases emerging from the same host plant. Examination of the larger, darker form showed this to be identical to material of X. bispinatus from Central and South America. Kirkendall & Jordal stated that X. bispinatus is larger that X. ferrugineus, but they provided no quantitative data. While Rabaglia did include measurements, his size range for X. ferrugineus probably included X. bispinatus. Wood’s treatment (1982) combined all 3 species so the measurements given are not useful. We include length and width measurements for all 3 species. Based on specimens from, X. bispinatus is clearly larger than X. ferrugineus with non-overlapping size ranges (Table 1). Including measurements from both species from Panama and other localities in Florida does broaden the respective size ranges of both species to the point that some overlap does occur. In part, this overlap has made distinguishing the 2 species more difficult when comparing smaller series of specimens from many localities. The material studied here provides the unique opportunity to compare sympatric, contemporaneous populations from the same host material. The 3 species are shown in Figs. 1 and 2. A comparison of characters useful in separating them is given in Table 1. Illustrations and characters are only given for females. In this group of ambrosia beetles males are reduced in size, flightless, and present as a very low proportion of the population. Consequently they are seldom encountered. All species of the tribe Xyleborini have a haplo-diploid sex determination system (males haploid) and inbred (Wood 1982).

96 Accepted by L. Kirkendall: 19 Mar. 2013; published: 5 Jun. 2013 FIGURE 1. Xyleborus bispinatus female. A. Dorsal habitus. B Lateral habitus. Xyleborus ferrugineus female. C. Dorsal habitus. D Lateral habitus. Arrows indicate location of major declivital spine on interstriae 3 and pronotal summit.

OCCURRENCE OF XYLEBORUS BISPINATUS IN SOUTHERN FLORIDA Zootaxa 3669 (1) © 2013 Magnolia Press · 97 FIGURE 2. Declivities. Xyleborus bispinatus female. A. dorsal aspect; B. angled view; C. lateral profile. Xyleborus ferrugineus female. D. dorsal aspect; E. angled view; F. lateral profile. Xyleborus impressus female. G. dorsal aspect; H. angled view; I. lateral profile. Arrows indicate location of major declivital spines and pronotal summit.

Of the characters cited by Kirkendall and Jordal (2006) we found the size and position of the major spines to be most consistent and useful for distinguishing X. bispinatus and X. ferrugineus. The frontal character (presence or absence of a carina) did not clearly differentiate our specimens. Kirkendall and Jordal (2006) noted that large interstrial setae were clearly visible in specimens of bispinatus on the declivity and elytral disc (Fig. 1 A,B) but sparse on the declivity and generally absent from the disc in specimens of ferrugineus (Fig. 1 C,D). This character clearly separates both species in southern Florida. Characters given by Rabaglia (2005) will clearly separate X. impressus from the other 2 species

12(11). Declivital interstriae 1 unarmed, interstriae 3 with three denticles: denticle near base subequal to larger middle denticle, small denticle near posterior margin; declivity distinctly sulcate, interstriae 2 impressed, strial punctures less distinct, declivity less shining (Figs. 2G–I)...... impressus Eichhoff - Declivital interstriae 1 armed by one small denticle at base, interstriae 3 with two or more denticles: denticle(s) near base small, denticle near middle of declivity distinctly larger than others; declivity flat, interstriae 2 not impressed, strial punctures distinct,declivity shining (Figs. 2A–F)...... 12’ 12’(12). Major denticle on interstriae 3 nearer declivital apex than to base (Figs. 2 D-F); pronotal summit not pronounced, anterior slope rounded in profile; transition between elytral disc and declivity rounded in profile (Fig. 1 D, 2F), interstrial setae sparse or absent on elytral disc (Fig. 1C,D) ...... ferrugineus (Fabricius) - Major denticle on interstriae 3 nearer declivital base than to apex (Figs. 2 A-C); pronotal summit pronounced, anterior slope abrupt in profile; transition between elytral disc and declivity abruptly flattened in profile (Fig. 1B, 2C), erect interstrial setae abundant on elytral disc almost to base...... bispinatus Eichhoff

TABLE 1. Comparison of females of 3 species of Xyleborus. Measurements for X. bispinatus and X. ferrugineus were taken from specimens collected at site 1. Measurements for X. impressus are from Rabaglia (2005). Character bispinatus ferrugineus impressus Length (mm) (average, site 1) 2.89 + .033 (n=17) 2.46 + .027 (n=12) Length (mm) (range, site 1) 2.80–3.00 2.40–2.55 Length (mm)(range, all areas) 2.80–3.20 2.40–2.90 2.0–2.5 mm Mature color brown- black (Fig. 1 A,B) reddish brown (Fig. 1 C,D) reddish brown Pronotal summit strongly pronounced (Fig. not pronounced (Fig. 1 C) not pronounced 1B) Anterior profile pronotum acutely angled (Fig. 1B) gradually curved (Fig. 1 D) gradually curved Major spines, declivital closer to base of declivity closer to apex of declivity 2 spines, subequal in size interstria 3 than apex (Fig. 2 A–C) than base (Fig. 2 D–F) (Fig. 2 G–I) Spine at base of interstria 1 on Present (Fig. 2 A–C) present (Fig. 2 D–F) Absent (Fig. 2 G–I) declivity Interstria 3 on declivity not or only slightly elevated not or only slightly elevated elevated above level of with respect to interstriae 1 with respect to interstriae 1 interstriae 1 and 2 (Fig. 2 G– and 2 (Fig. 2 A–B) and 2 (Fig. 2 D–E) H) Declivital profile Abrupt, flattened (Fig. 1B, Gradually rounded (Fig. 2F) Gradually rounded (Fig. 2I) 2C)

Xyleborus bispinatus specimens were collected from seven sites in Florida; six sites are located in South Florida (Miami-Dade Co.) and one in central Florida (Highlands Co.) (Table 2). In sites 1–6, X. bispinatus was associated with wilted trees of avocado and swampbay, Persea palustris (Raf.) Sarg and in site 7 with foxtail palm Wodyetia bifurcata Irvine (Table 2). Site 1 is a natural area with abundant swampbay trees. This site was extensively sampled to determine the presence and abundance of X. bispinatus. First, wood samples of 14 wilted swampbay trees were collected and placed in emergence chambers to determine the ambrosia beetles emerging from them, as described in Carrillo et al. (2012). The wood samples were held for 4 months and X. bispinatus and X. ferrugineus identified weekly. In addition, traps consisting of a metal wire mesh (25 x 25 cms) impregnated with Tangle-foot ® were attached to the tree trunk of 40 sentinel trees (20 avocados and 20 redbays, Persea borbonia (L.) Spreng). Each sentinel plant was separated by at least 100 feet from each other. The traps were changed monthly during four months to determine the number of X. bispinatus and X. ferrugineus captured per trap. The number of X. bispinatus that emerged from the wood samples ranged from 2-717 individuals and from 2-92 of X. ferrugineus. Both species were found together in 12 out of 14 trees that were sampled. Xyleborus bispinatus was more abundant than X. ferrugineus in all but one of the wood samples held in emergence containers (Fig. 3A). Similarly, X. bispinatus was captured more than X. ferrugineus in the traps placed on sentinel plants (Fig. 3B). The presence of both X. bispinatus and X. ferrugineus was determined in sites 2-7 but their abundance was not assessed.

OCCURRENCE OF XYLEBORUS BISPINATUS IN SOUTHERN FLORIDA Zootaxa 3669 (1) © 2013 Magnolia Press · 99 FIGURE 3. A. Average number (mean ± standard error) of adult beetles that emerged from wood samples from 14 swampbay trees held in emergence chambers for 4 months. B. Average number of adult beetles captured per week on sticky traps placed on the tree trunks of sentinel plants.

Specimens from site 1 have been deposited in the Florida State Collection of Arthropods, Texas A&M University, Michigan State University and U.S. National Museum collections.

TABLE 2. Localities, dates and host plants from which X. bispinatus and X. ferrugineus were collected. Site Locality Coordinates Plant Sampling date 1* Miami, Miami-Dade, Co. 25°43'37.96"N–80°28'36.16"W Persea palustris 1/20/2012 2 Miami, Miami-Dade, Co. 25°35'09.99"N–80°26'18.65"W Persea americana 5/18/2012 3 Miami, Miami-Dade, Co. 25°44'55.81"N–80°26'19.49"W Persea palustris 6/24/2012 4 Homestead, Miami-Dade Co. 25°25'32.80"N–80°30'33.87"W Persea americana 7/26/2010 5 Homestead, Miami-Dade Co. 25°30'21.62"N–80°31'35.39"W Persea americana 7/8/2010 6 Venus, Highlands Co. 27°12'53.94"N–81°20'49.38"W Persea palustris 9/19/2012 7 Miami, Miami–Dade Co. 25°34'11.97"N–80°28'37.87"W Wodyetia bifurcata 3/11/2012

Literature cited

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