Thyreodon atriventris, (CRESSON), 1966

Gauld, Ian D. & Janzen, Daniel H., 2004, The systematics and biology of the Costa Rican species of parasitic wasps in the Thyreodon genus-group (Hymenoptera: Ichneumonidae), Zoological Journal of the Linnean Society 141 (3), pp. 297-351 : 339-342

21. THYREODON ATRIVENTRIS (CRESSON)

Ophion atriventris Cresson, 1874: 374 . Holotype ♀, MEXICO (PANS) [examined].

Athyreodon thoracicus Ashmead, 1900a: 87 . Holotype ♀, ECUADOR (USNM) [examined].

Thyreodon grenadensis Ashmead, 1900b: 270 . Holotype ♀, GRENADA (BMNH) [examined].

Macrophion ornatus Szépligeti, 1905: 33 . Lectotype ♂, BELIZE, designated by Townes & Townes, 1966: 186 (TM) [examined].

Athyreodon atriventris (Cresson) Hooker, 1912: 102 .

[ Macrophion fulvescens (Cresson) Morley, 1912: 14 . Misidentification.]

Macrophion grenadensis (Ashmead) Morley, 1912: 15 . Thyreodon atriventris (Cresson) Townes & Townes, 1966: 186 .

Fore wing length 21.8–27.8 mm; clypeus rather flat, with apex out-flared, with a rounded point medially; malar space more or less obliterated; maxillary palp long, with second palpomere strongly broadened and slightly inflated; lower face centrally finely punctate; frons with a single weak vertical crest between antennal sockets and without a low carina extending from outer rim of antennal sockets upwards, close to and parallel with eye margin; frons centrally rugose; ocelli very large, the lateral ocellus contiguous with eye; head in dorsal view with gena rather evenly rounded behind eye, occipital carina strong, its lower end sharp, but not reaching hypostomal carina; antenna setaceous, with 57–63 flagellomeres, the 20th slightly elongate, 1.1–1.2 times as long as broad, the subapical ones with setae which are longer than the diameter of the flagellomere. Pronotum short with anterior margin strongly and broadly reflexed, and with posterior margin centrally weakly swollen, forming a low rounded ridge which is separated from the anterior margin by a deep U-shaped groove; epomia absent; propleuron sparsely punctate, with lower corner rounded, peripherally not impressed, slightly flared outwards; mesoscutum finely and sparsely punctate, with narrow, shallow, slightly transversely striate notauli which are almost confluent posteriorly, inner anterior margin of notaulus unspecialized; scutoscutellar groove moderately deep, long, laterally margined by thickened, simple carinae; scutellum smooth, very finely punctate, rather flat and broad posteriorly; mesopleuron finely punctate, with a rather broad, shallow, and slightly transversely striate sternaular impression; metapleuron finely punctate to granulate, with a few rugae dorsally; propodeum laterally slightly flattened, very coarsely reticulate, with a sharp strongly raised tubercle above and behind the spiracle; propodeum posterodorsally very coarsely reticulate, with a median anterior tubercle, centrally without a trace of a shallow longitudinal impression. Fore leg of female rather slender, with coxa with a bluntly rounded, low protuberance behind trochanteral insertion, with 5th tarsomere 0.7–0.8 times as long as preceding two tarsomeres, with tarsal claw long and with fine, close pectinae; hind coxa in profile moderately large, its hind end projecting well behind level of hind end of propodeum; hind femur slender, about 6 times as long as maximally deep; hind tarsus of male with dense, moderately long pubescence ventrally. Fore wing with abscissa of Cu 1a between Cu 1b and 2 m-cu 1.65–1.95 times as long as abscissa of Cu 1 between cu-a and 1 m-cu. Metasoma with tergite I moderately slender, anteriorly subcylindrical or slightly dorsoventrally depressed; tergite II, in lateral view, 1.5–1.7 times as long as posteriorly deep. Male with subgenital plate small and convex, with rather sparse hair; claspers quite long, the dorsal apex produced into a moderately long spine-like projection, the lower margin quite sharply angulate before apex; aedeagus in profile with apex expanded, apically weakly flattened, with a sharp lateral keel.

A mainly orange-brown species with interocellar area, flagellum, metasoma, hind femur, tibia and tarsus blackish brown, fore and mid tarsus slightly infuscate; wings hyaline with basal cell, distal 0.7 or so of marginal cell and proximal part of 3rd submarginal cell blackish infumate.

Variation: Two wild-caught individuals from ACG dry forest are smaller than normal (fore wing length about 17 mm) with fewer flagellomeres (49–51), a slightly less reticulate propodeum and more reddish hind femora. The status of these specimens is not clear, but they may represent another cryptic species. They are listed separately below.

Remarks: Thyreodon atriventris is very similar to Thyreodon rufothorax , and these taxa are easily distinguished from other species by the combination of very large ocelli and eyes (which are contiguous, and the latter occlude the malar space almost entirely), coloration and pattern of the fore wings. These two species have been consistently grouped together under the name T. atriventris in museum collections, a syn- onymy formally proposed by Townes ( Townes & Townes, 1966) and repeated in Gauld (1988). Here we demonstrate that the two are distinct species. T. atriventris and T. rufothorax are most easily distinguished by the colour of the hind coxa, which is orange-brown in T. atriventris and black in T. rufothorax . Additionally, the claspers of the male genitalia of T. atriventris have a pronounced and externally visible ventral angulation that is lacking in T. rufothorax ( Figs 62, 63 ). T. atriventris also usually has the basal cell of the fore wing more or less entirely darkly infumate ( Fig. 10 ), whereas T. rufothorax has this cell partially hyaline or only weakly palely infumate ( Fig. 9 ). Finally, they are parasitoids of different species of caterpillars (see below).

Biological notes: Thyreodon atriventris is a wideranging species that definitely occurs from Mexico south to Ecuador, as do its two species of Moraceaeeating host caterpillars. It occurs throughout Costa Rica below about 600 m elevation (and is sympatric over this range with its sibling, Thyreodon rufothorax ). It comes frequently to lights placed out in the forest, which, coupled with its large size and gaudy colour, is the reason why there are so many individuals in the INBio collections (see below). From this we also deduce that it searches for caterpillars at night (as well as possibly in the daytime). It (and/or T. rufothorax ) has been encountered in the daytime visiting the fly- and wasp-pollinated flowers of Allophylus occidentalis (Sapindaceae) , Forsteronia spicata (Apocynaceae) and Trigonia rugosa (Trigoniaceae) (along with Rhynchophion flammipennis ).

All 35 rearing records of Thyreodon atriventris are from caterpillars of Pachylia ficus and Pachylia syces (Sphingidae) [e.g. 78-SRNP-81; 81-SRNP-316a; 85-SRNP-417; 86-SRNP-192; 86-SRNP-214; 91-SRNP-1341; 93-SRNP-2508; 93-SRNP-2645; 94-SRNP-3699; 94-SRNP-4824; 99-SRNP-8461; 99-SRNP-8576; 99-SRNP-8699; 99-SRNP-8713; 99-SRNP-8715; 01-SRNP-14695; 01-SRNP-14701; 01-SRNP-14835; 01-SRNP-14836] ( Janzen & Hallwachs, 2003). These caterpillars were feeding on Brosimum alicastrum , Maclura tinctoria , Castilla elastica and four species of Ficus (all in the Moraceae ). These are all the Moraceae in ACG dry forest except for three more species of Ficus . These two large green caterpillars are superficially very similar, and it is possible that a few of the ‘ P. ficus ’ records were in fact P. syces (the prepupa of P. ficus is brick red-orange dorsally, whereas the prepupa of P. syces is black and cream ringed with a red head). Pachylia ficus also has a ‘rotten twig’-coloured morph as well as the (more common) green morph (see images in Janzen & Hallwachs, 2003), and T. atriventris has been reared from both colour morphs.

Pachylia caterpillars make a shallow and nearly silk-free pupation chamber in the litter, and T. atriventris spins its large hard, tough, cocoon in the centre of this chamber. Although all caterpillars that have been parasitized were penultimate or ultimate instar when collected, it is possible that parasitization occurs at an earlier instar because it does so with other species of Thyreodon . When univoltine, and therefore dormant through the 6-month dry season, the larva remains as a wasp prepupa in the cocoon until about 1 month before it ecloses.

Thyreodon atriventris has been reared from both ACG dry forest and rain forest. Although Pachylia caterpillars occur throughout the ACG, not enough have been found in the wetter areas to comment on the proportion of parasitization by T. atriventris . Of 387 wildcaught dry forest Pachylia caterpillars, 9% were attacked by T. atriventris . However, 13% of these 387 caterpillars were killed by Cryptophion wasps ( Ichneumonidae ) or by tachinid fly larvae before they reached the prepupal stage, and some of these caterpillars may also have had T. atriventris larvae in them.

T. atriventris stays in the cocoon for 30–41 days, 120–198 days or 292–350 days ( Janzen & Hallwachs, 2003). Lineages that eclose in 1–1.5 months are probably having at least two generations in the first half of the rainy season (and could conceivably have another at the end of the rainy season). Those that eclose after 3–5 months may have a second generation during the end of the rainy season (a time when there are Pachylia larvae present, albeit at much reduced numbers as compared with the first 3 months of the rainy season). Those that remain about 1 year in the cocoon are being univoltine. We have no knowledge of adult survival, but adults are not encountered at light or in Malaise traps during the dry season (a time when there are no dry forest Pachylia caterpillars, even though Ficus at least stays evergreen), and are most common at lights during the early rainy season, when they are presumably eclosing from cocoons spun either at the beginning or at the end of the previous rainy season. In short, T. atriventris has 2–3 generations per 6-month rainy season but some individuals behave in a univoltine manner.

Material examined: Holotype ♀, ( Ophion atriventris Cresson ) MEXICO, Orizaba ( PANS) . Holotype ♀, ( Athyreodon thoracicus Ashmead ) ECUADOR ( USNM) . Holotype ♀, ( Thyreodon grenadensis Ashmead ). GRENADA, Baltasar , windward side ( BMNH) . Lectotype ♂ ( Macrophion ornatus Szépligeti ) BELIZE ‘ British Honduras’ ( TM) .

Non-type material: COSTA RICA: Alajuela Prov.: 2 ♀, 1 ♂, Finca San Gabriel, 2 km W Dos Rios, 600 m, vi.1988 (Gauld & Mitchell) (BMNH); 2 ♂, same locality, vi.1989 (Parataxonomists) ( INBio ); 1 ♀, San Cristobal, 600–620 m, iii.1998 ( Quesada ) ( INBio ): Guanacaste Prov.: 1 ♂, Barra Honda National Park, 100 m, v.1988 (Gauld) (BMNH); 1 ♂, Barra Honda National Park, Los Mesones, 100 m, v.1995 (Reyes) ( INBio ); 4 ♂, Barra Honda National Park, 3 km NW Nacaome, 100 m, v.1993, viii.1994 (Reyes) ( INBio ); 5 ♀, 14 ♂, Guanacaste National Park, reared as per data above (Janzen & Hallwachs) (JHVC); 2 ♀, Guanacaste National Park, Estacion Los Almendros, 300 m, x.1993 (López) ( INBio ); 1 ♂, Guanacaste National Park, Cerro el Hacha , 400 m, xi–xii.1991 (Lopez) ( INBio ); 4 ♀, 5 ♂, Guanacaste National Park, Estacion Maritza, W slope Volcán Orosi, 560 m, vi, viii.1990, ii–iii.1992 (Blanco) ( INBio ); 2 ♀, 1 ♂, Guanacaste National Park, Estacion Murcielago, 8 km SW Cuajiniquil, 100 m, vi.1994 ( Caño ) ( INBio ); 6 ♀, 2 ♂, Guanacaste National Park, Estacion Pitilla, 9 km S Santa Cecilia, 700 m, x.1990, iv.1991, vi.1992, iv–v.1993 (Rios & Moraga) ( INBio ); 11 ♀, Guanacaste National Park, Finca Jenny, 30 km N Liberia, 240 m, vi–viii.1993, vi–vii.1995 (Araya) ( INBio ); 1 ♀, 1 ♂, Palo Verde, 10 m, vi–vii.1991 (Chavarria) ( INBio ); 1 ♀, same locality, vi.1988 (Arguedas) (UCRC); 3 ♀, 1 ♂, Rincon de la Vieja National Park, Estacion Las Pailas, 800 m, i.1993, v.1994 (Taylor) ( INBio ); 16 ♀, 6 ♂, Santa Rosa National Park, 300 m, v–vi.1985 (Janzen & Hallwachs) ( INBio ); 2 ♀, Tenorio Zona Protectora, Rio San Lorenzo, Tierras Morenas, 1050 m, i.1993, viii.1994 (Rodriguez) ( INBio ): Heredia Prov.: 1 ♀, Braulio Carrillo National Park, Estacion Magassay, 200 m, v.1991 (Zumbado) ( INBio ); 2 ♀, La Selva Biological Station, 50–150 m, iii–iv.1987 (Chavarria) ( INBio ); 1 ♀, same locality, iv.1989 (Hespenheide) (BMNH); 1 ♀, same locality, i.1992 (Lezama) (UCRC); 1 ♂, Los Arbolitos, 30 m, iii.1993 (Araya) ( INBio ): Limón Prov.: 1 ♀, 5 ♂, Tortuguero National Park, Cerro Tortuguero, 150 m, v.1990, x.1991, iv– v.1992, vii.1993, iii.1994 (Delgado & Solano) ( INBio ); 1 ♂, Amubri, 70 m, i.1994 (Gallardo) ( INBio ): Puntarenas Prov. 7 ♀, 5 ♂, Carara Biological Reserve, Estacion Quebrada Bonita, 50 m, viii–xi.1989 (Gauld) (BMNH); 22 ♀, 12 ♂, same locality, xii.1989, v–vi.1990, v–vi, xi.1992, viii.1993, i.1994 (Parataxonomists) ( INBio ); 1 ♀, 3 ♂, Cerro de Oro, Albergue, 50–150– 170 m, v– viii.1995 ( Gamboa ) ( INBio ); 2 ♀, Estacion Agujas, Sendero Purraja, 300 m, xi.1997, iii.1998 (Azofeifa) ( INBio ); 6 ♀, 5 ♂, Osa Peninsula, Corcovado National Park, Estacion Sirena, 0–100 m, ix–xi.1989 (Gauld) (BMNH); 39 ♀, 5 ♂, same locality, x.1989, i.1990, xi.1991, i–v.1993, i.1994, viii.1995 (Fonseca & Picado) ( INBio ); 1 ♀, Osa Peninsula, Estacion Esquinas, 0 m, ii.1993 ( Segura ) ( INBio ); 2 ♀, 5 ♂, Osa Peninsula, Rancho Quemado, 200 m, viii, xii.1991 (Marin & Quesada ) ( INBio ); 1 ♀, Quepos, Manuel Antonio National Park, ii.1993 (Varela) ( INBio ): San José Prov.: 1 ♀, Braulio Carrillo National Park, Estacion Carrillo, 730 m, iii.1990 (Chacón) ( INBio ); 1 ♂, Braulio Carrillo National Park, Estacion Carrillo, 700 m, vii.1990 (Parataxonomists) ( INBio ); 1 ♂, 2.5 km W Cuidad Colon, 700–900 m, xii.1995 (Rifkind) (UCRC); 1 ♂, Pozo Azul, Rio Parrita, xii.1961 (Wille) (UCRC).

Small individuals: COSTA RICA: Guanacaste Prov.: 1 ♀, Guanacaste National Park, Finca Jenny , 31 km N Liberia, 240 m, vi.1993 (Araya) ( INBio ); 1 ♀, Santa Rosa National Park , 300 m, v.1985 (Janzen & Hallwachs) ( INBio ) .

Figures

Figures 53–63. Apex of metasoma and male genital capsule, lateral; 53, T. maculipennis; 54, T. erythrocera; 55, T. whitfieldi; 56, T. laticinctus; 57, T. zitaniae; 58, T. papei; 59, T. morosus; 60, T. schauffi; 61, T. darlingi; 62, T. rufothorax; 63, T. atriventris.

Figures 7–14. Fore wings, showing colour patterns. 7, Rhynchophion flammipennis, normal form. 8, Rhynchophion flammipennis, dark form. 9, Thyreodon rufothorax. 10, T. atriventris. 11. T. maculipennis. 12. T. walkerae. 13. T. zitaniae. 14. T. papei.