Agallissus lepturoides (Duponchel & Chevrolat, 1841)

Austin, Thomas, Heffern, Daniel, Gemmill, Robert, Raber, Brian & Quinn, Mike, 2018, Notes on the biology and distribution of the tribe Agallissini in North America (Coleoptera: Cerambycidae: Cerambycinae), Zootaxa 4457 (3), pp. 444-454 : 444-446

Agallissus lepturoides (Duponchel & Chevrolat, 1841)

[ Figs. 1 & 2 ]

History. This species was first reported from Texas, without further data, by LeConte (1873) as Cryptopleura grata Haldeman, 1854 , and subsequently listed thereafter as occurring from Texas to Honduras in catalogs and other works (i.e. Linsley 1964; Hovore et al. 1987). The first collecting record from Texas known to us since LeConte’s time was by R. M. Brattain, 2-IV-1999 and was taken by beating on Sabal mexicana Mart. along the edge of the Sabal Palm Sanctuary (SPS), Cameron County, Texas. (R. M. Brattain, pers. comm.). The next specimen was collected in the SPS by one of the authors (Raber), 18-X-2008, while beating on a leaf of a short Sabal palm tree. The subsequent search for additional specimens was centered in the SPS, which is a relatively small preserve containing a tiny fraction of the original sabal palm forest biotic community that was once dominant in the Lower Rio Grande Valley (LRGV) in Cameron and Hidalgo counties of Texas and adjacent parts of Mexico ( Jahrsdoerfer & Leslie 1988). Hovore et al. (1987) speculated that this species would be associated with palms similarly to its close relatives, Zagymnus and Osmopleura .

Biological notes. Three of the authors (Heffern, Raber, and Quinn) and Edward Riley (TAMU), made concerted efforts in 2009 and 2010 to find larvae and adult specimens and to record observations as part of a larger study to document rare Coleoptera in the LRGV. During February, March, and April of those years, numerous dead petioles of Sabal mexicana were found that contained larvae, pupae, and teneral adults (first host record). Sites discovered within Cameron County with Agallissus included: the SPS, the Southmost Unit and the Boscaje de la Palma Unit of the LRGV National Wildlife Refuge, and along an irrigation ditch by Paloma Blanca Road about 2 km northwest of the SPS. The Boscaje de la Palma Unit, with re-vegetation in progress, is of comparable size to the SPS and borders it on the west side. Due to the healthy population of Agallissus encountered at the SPS, it is probable that it occurs widely around Brownsville where remnant Sabal palms naturally occur or where they have been re-introduced. Non-native palms in Cameron County were not examined for evidence of adult emergence.

Leaf stalks of mature S. mexicana vary in length from approximately 1 to 3 meters, in width from 2 to 6 centimeters, and in thickness from about 1.5 to 3 centimeters. Larvae, pupae, and adults were found by carefully cutting a dry, dead leaf stalk lengthwise or cutting across it perpendicularly and looking for frass. Infested leaf stalks were usually found still attached to a palm immediately below healthy upper leaves. Occasionally they were found lying on the ground below tall healthy palms. Leaf stalks trimmed along walking trails through the SPS were piled up, and even within those, larvae were found.

Larval frass trails are rather straight ( Fig. 10 ), as would be expected in the narrow petiole of a palm frond. Trails were moderately to very tightly packed with frass, typically about 0.3 to over 1 m in length after full larval development. Larvae appear to orient their feeding in a downwards direction with gravity. Whether the leaf stalk is still firmly attached horizontally, or broken and dangling vertically, affects which direction larvae feed and form pupal cells. Rarely, larvae would develop in or near the base (boot) of the stalk after the frond had been broken or cut off. This resulted in the larva being confined to a stub on the palm tree which would force it to feed in a restricted space. Thus, pupation may occur anywhere from the base to the extreme distal end of the leaf stalk. Infested leaf stalks may break due to weakness caused by larval feeding in conjunction with the weight of the dead frond or wind. Old emergence holes were observed on both the upper and lower surfaces of leaf stalks and were elliptical in shape, approximately 7 mm by 4.5 mm. A larva does not create an opening and plug it with frass, but simply positions its body so that it must only chew through a thin layer of stalk in order to emerge. There was no evidence to indicate that living fronds are used for larval development. Occasionally, one large and one small larvae were found in the same leaf stalk, which suggests that a female may be attracted to a leaf stalk that has been dead for a few months or perhaps as long as a year.

Dead leaf stalks found to contain larvae or pupae were cut into short sizes (<0.5 m) and stored in containers. They were occasionally sprayed with water to simulate rainfall and were allowed to dry before closing the container. Agallissus adults emerged from March to July when frond segments were stored in outside containers in the Houston area, suggesting that adults are active much of the year, excluding winter, and stayed alive in captivity for as long as 4–5 weeks. Adults rest with their antennae held straight forward, parallel to the body. Agallissus specimens ranged in size from 11.5 to 20 mm. In general, females tend to be slightly larger than males. Two small males had reduced yellow markings, ( Fig. 2 ), otherwise there was little variation in the maculations of the elytra.

Other arthropods were found in abandoned larval tunnels in leaf stalks, including ants, caterpillars, and spiders. Other exit holes, smaller and nearly round, were observed on some stalks, generally in the distal half, and were apparently created by the emergence of an anthribid beetle, Phoenicobiella schwarzii (Schaeffer, 1906) ( Coleoptera : Anthribidae ), which was also reared on occasion. Numerous traps in the SPS, including Lindgren funnel traps, UV light traps, flight intercept traps, and ethanol-baited traps only produced a single specimen of Agallissus . Thus, nearly all specimens were collected as teneral adults, pupae, or larvae from the dead stalks of the palm fronds.

Distribution. A distribution map ( Fig. 14 ) for Agallissus lepturoides was prepared based on records from DJHC, TAMU, FSCA, RMBC, Gutiérrez & Noguera (2015), Noguera & Chemsak (1996), Chemsak et al. (1980) and Haldeman (1854).

Figures

FIGURES 1–4. 1. Agallissus lepturoides (typical pattern), female. 2. Agallissus lepturoides (melanistic form), male. 3. Osmopleura chamaeropis (typical color), female. 4. Osmopleura chamaeropis (atypical dark color), male.

FIGURES 9–11. 9. Zagymnus clerinus (rare black form), female. 10. Larval workings of Agallissus lepturoides in petiole. 11. Zagymnus clerinus ovipositing.

FIGURE 12–14. 12. Zagymnus clerinus exit hole in a Sabal palmetto boot. 13. A transplanted Sabal palmetto showing several Z. clerinus exit holes. 14. Known distribution of Agallissus lepturoides (circles: specific locations, triangle: state record, square: country record).