DISTRIBUTION:

The Arsenura thomsoni moth (wingspan: males: 133-165mm; females: 162mm) flies in
French Guiana: Inini, Saul, Piste de Belizon, Piste Coralie, Roura-Kaw, Regina;
Venezuela: Bolivar and maybe Amazonas;
Guyana: Omai;
Brazil: Para and Mato Grosso, and possibly Roraima, Amazonas, Acre and Rondonia;
eastern Ecuador: Sucumbios CL, and possibly northern Napo WO, and possibly Orellana; and in Peru: Loreto; at elevations of 100m to 1350m. I suspect it also flies in Suriname.

Based on Entomo-Satsphingia Jahrgang 3 Heft 3 28.06.2010, examination of genitalia reveals four Arsenura sylla subspecies. There are also two A. thomsoni subspecies in the Sylla Group. See the comparison chart at the bottom of this page. A fifth sylla subspecies, Arsenura sylla maranhensis has been added in 2013. I do not have images of that subspecies from Maranhao, Brazil.

Arsenura thomsoni male, 142mm, Belizon, French Guiana, courtesy of Johnny Marchant.

This species is very similar to A. sylla sylla, but the basic ground colour of thomsoni is much paler and hints toward yellow or olive brown. The white axis of the hindwing is almost nonexistent.

Arsenura thomsoni male, Kaw, French Guiana,
February 9, 2011, courtesy of Andres Urbas.

FLIGHT TIMES AND PREFERRED FOOD PLANTS:

FGS reports a flight in December. There may be additional flights.

The Arsenura thomsoni larval hosts are unknown.

ECLOSION, SCENTING AND MATING:

Arsenurini males use their antennae to seek out females which scent at night.

Arsenura thomsoni female (French Guiana), courtesy of Carlot Didier.

Arsenura thomsoni female, Nachr. entomol. Ver. Apollo, N.F. 26 (4): 177-180 (2005)

Arsenura thomsoni female (verso), Nachr. entomol. Ver. Apollo, N.F. 26 (4): 177-180 (2005)

EGGS, LARVAE AND PUPAE:

Mature larvae descend tree trunks to excavate and pupate in subterranean chambers.

Larval Food Plants

It is hoped that this alphabetical listing followed by the common name of the foodplant will prove useful. The list is not exhaustive. Experimenting with closely related foodplants is worthwhile.

Arsenura sylla Subgroup: sylla subspecies: Arsenura sylla sylla Nominate sylla is reported in Suriname, Venezuela, Guayanas, northern Brazil, eastern Ecuador and north eastern Peru as a Guayanan-Amazonian species. Although the four subspecies depicted in this table have slight character differences, I do not know how consistent those characters would be in a large series from each respective range area. Nominate sylla (left) seems to have the broadest, least apically produced forewings, with a relatively large crescentric forewing cell mark. A. s. niepelti (right)appears to have the smallest dark cell markings. Arsenura sylla niepelti Subspecies niepelti is reported from western Colombia, Nicaragua, Costa Rica, Panama; and I am pretty sure it ranges into north western Ecuador. Arsenura sylla hercules Subspecies herucles is reported from southeastern Brazil: Espirito Santo, Rio de Janeiro, Parana, Sao Paulo. It is very large and has more coppery tint. Subspecies hercules (left) also has sub-crescentric fw cell mark and perhaps the least rounded fw apex. Hindwing projection suggest isosceles triangle in even taperings on both sides of projection. Subspecies winbrechlini (right) seems to have the most elongate forewings with a distinctly oval fw cell mark and markedly oblique outer margin. The lighter area along the costa has a slight orangey tint. Arsenura sylla winbrechlini Subspecies winbrechlini is reported thus far only from La Paz, Bolivia. Arsenura sylla maranhensis image on home computer only mfwl: 75-80mm; Maranhao, Brazil, 480m: Subspecies maranhensis (left) is thus far the smallest subspecies in the group. It appears the forewing apex is not at all produced. The fw outer margin is relatively straight without any concave section. The hindwing tail is relatively short and thick. The forewing cell mark is a thick, black, oblong shape with a narrow, elongate and lighter, interior streak. On the A. sylla sylla file there is an image, reported from eastern Ecuador, that looks more like subspecies hercules than it does sylla. Perhaps these moths are quite variable; perhaps some need to be synonymized; perhaps some need to be elevated to full species status with some range extensions, etc.. Arsenura sylla Subgroup: thomsoni subspecies: Arsenura thomsoni thomsoni French Guiana, Venezuela, Guyana, northern Brazil, probably Suriname as a Guyano-Amazonian species. Nominate thomsoni (left) is very similar to A. sylla sylla but basic ground colour is much paler, hinting toward yellow or olive brown. Hw white axis: almost nonexistent. Fw subterminal white line almost straight, without strong outward projections. Subspecies lemairei (right), which may be elevated to full species status, has hinwings without smooth outer margins. Arsenura thomsoni lemairei Subspecies lemairei is reported in north western Brazil and eastern Colombia, northeastern Ecuador and northern Peru.

The pronunciation of scientific names is troublesome for many. The "suggestion" at the top of the page is merely a suggestion. It is based on commonly accepted English pronunciation of Greek names and/or some fairly well accepted "rules" for latinized scientific names.

The suggested pronunciations, on this page and on other pages, are primarily put forward to assist those who hear with internal ears as they read.

There are many collectors from different countries whose intonations and accents would be different.

Some of the early describers/namers chose genus and species names indicating some character of the insect, but more often, they simply chose names from Greek or Roman mythology or history.

Those species names which end in "ensis" indicate a specimen locale, and those which end in "i", pronounced "eye", honour a contempory friend/collector/etc.

I do not know the source of the genus name "Arsenura" chosen by Duncan in 1841.

The species name "thomsoni" is honourific for Thomson.

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