Thyreodon laticinctus, CRESSON, 1874

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 : 321-322

6. THYREODON LATICINCTUS CRESSON

Thyreodon laticinctus Cresson, 1874: 376 . Holotype ♀, MEXICO (PANS) [examined].

Thyreodon principalis Smith, 1879: 230 . Holotype ♀, COSTA RICA (BMNH) [examined].

Thyreodon zonatus Szépligeti, 1906: 134 . Lectotype ♂, BOLIVIA, designated by Townes & Townes, 1966: 189 (TM) [examined].

Oleter selenaction Shestakov, 1926: 259 . Lectotype ♀, ‘Nova Grenada’, designated by Townes & Townes, 1966: 189 (ZISP).

Fore wing length 21.2–22.8 mm; clypeus convex, with apex strongly pointed medially; malar space about 0.5 times basal mandibular width; maxillary palp long with second palpomere strongly broadened and flattened; lower face centrally punctate with a few distinct rugae; frons with a pair of dorsally divergent crests between antennal sockets and with a low but sharp carina extending from outer rim of antennal sockets upwards, close to and parallel with eye margin; frons centrally rugose; ocelli small, the lateral ocellus separated from eye by about 1.3 times its own maximum diameter; head in dorsal view with gena rather evenly rounded behind eye, occipital carina strong, its lower end sharp, abruptly in-turned but not reaching hypostomal carina; antenna setaceous, with 51–55 flagellomeres, the 20th slightly transverse, 0.8– 0.9 times as long as broad, the subapical flagellomeres with setae that are slightly longer than the diameter of the flagellomere. Pronotum short with anterior margin strongly and broadly reflexed, and with posterior margin centrally swollen, forming an angular, quadrate ridge which is separated from the anterior margin by a deep U-shaped groove ( Fig. 22 ); epomia weak but discernible on upper part of pronotum; propleuron sparsely punctate, with lower corner rounded, peripherally not impressed; mesoscutum finely punctate, with broad, shallow, reticulated notauli which are confluent posteriorly, inner anterior margin of notaulus forming a low, sharp ridge; scutoscutellar groove very deep, long, laterally margined by very strongly raised, thickened, simple carinae; scutellum rugose-punctate, convex; mesopleuron finely to moderately closely punctate, without a sharp sternaular impression; metapleuron finely punctate with a few obscure diagonal ridges; propodeum laterally slightly flattened, finely rugose, with a sharp (and often rather smooth) low ridge above and behind the spiracle; propodeum posterodorsally finely rugose, with stronger transverse rugae posterolaterally, centrally with a single shallow longitudinal impression. Fore leg of female rather stout, with coxa with a bluntly rounded protuberance behind trochanteral insertion; 5th tarsomere subequal in length to preceding two tarsomeres, with tarsal claw long and with fine, close pectinae; hind coxa in profile moderately small, its hind end more or less level with 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 0.85–1.00 times as long as abscissa of Cu 1 between cu-a and 1 mcu. Metasoma with tergite I slender, anteriorly slightly laterally compressed; tergite II, in lateral view, 2.2–2.5 times as long as posteriorly deep. Male with subgenital plate small and convex, covered with dense coarse black hair; claspers quite long, the dorsal apex usually produced into a moderately long spinelike projection, the lower margin quite sharply angulate before apex ( Fig. 56 ); aedeagus in profile with apex up-turned, weakly inflated, rounded.

A black species with tergite III and most of tergite IV bright lemon-yellow; wings uniformly blackish infumate.

Remarks: Thyreodon laticinctus is most easily distinguished by its very striking colour pattern ( Fig. 4 ), being entirely black except for tergites III and IV, which are bright lemon-yellow. In Costa Rica only one other species has a similar colour pattern, T. whitfieldi . These two species are extremely similar and have been confused in all collections to date. However, they differ subtly but consistently. T. laticinctus has the propodeum with a low, sharp (and often polished) ridge above and behind the spiracle, has tergite II ( Fig. 20 ), in lateral view, 2.2–2.5 times as long as posteriorly deep, has a slightly rugose central region on the lower face, and has the hind femur slender about 6 times as long as deep. T. whitfieldi has the propodeum with the upper anterior part evenly convexly rounded, without a sharp ridge above and behind the spiracle ( Fig. 19 ), has tergite II, in lateral view, 1.6– 2.0 times as long as posteriorly deep, has the lower face centrally regularly closely and coarsely punctate, and has the hind femur slightly stouter. Only T. laticinctus has been reared from Xylophanes anubus , again emphasizing its distinctness from T. whitfieldi , which has been reared from Xylophanes chiron .

Biological notes: Thyreodon laticinctus is a rather common and widespread species that has a range extending from tropical Mexico south to Bolivia (though again, as in other cases, it may be that many museum specimens of ‘ T. laticinctus ’ are T. whitfieldi or yet other species). Both Thyreodon laticinctus and Thyreodon whitfieldi (the two are indistinguishable in flight) are occasionally encountered flying 50–150 cm above the ground through the understorey of relatively intact Costa Rican rain forest, lower elevation cloud forest and their intergrades, during full daylight and in bright sunlight. Their conspicuousness (black and yellow), abundance and slow flight are reflected in the large number of specimens of both species (and both sexes) in the INBio collections. Neither species has ever been encountered in classical Guanacaste Province dry forest (the two wild-caught records of T. laticinctus from Cerro El Hacha and the rearing records from the western lower slopes of Volcán Orosi are from an ACG forest type that is in the moist intergrade between classical lowland dry forest and bordering rain forest). T. laticinctus does not come to lights and is almost never caught in Malaise traps.

Thyreodon laticinctus has a wider geographical distribution in Costa Rica than does Thyreodon whitfieldi , with the latter species apparently restricted to the intermediate to upper elevation areas (600–1000 m) of the ACG.

Thyreodon laticinctus is unambiguously a specialist on caterpillars of Xylophanes anubus (Sphingidae) feeding on various species of Psychotria (Rubiaceae) , a common member of the rain forest understorey (all rearing records [98-SRNP-13527; 98-SRNP-14002; 98- SRNP-14139; 99-SRNP-698; 99-SRNP-873; 99-SRNP- 8959; 99-SRNP-8969; 99-SRNP-12437; 00-SRNP-789; 00-SRNP-1289] are from this caterpillar species; Table 1). This wasp occurs at a very low density. Of 382 Xylophanes anubus caterpillars found in the habitats where it has been reared, only ten (2.6%) were attacked. The strong host-specificity of T. laticinctus is particularly dramatic when it is considered that along with the Xylophanes anubus caterpillars collected were another 800 Xylophanes caterpillars of 11 different species, 512 of which were found feeding on Psychotria spp.

Oviposition may occur as early as ante-penultimate (3rd) instars. The larva exits the prepupal caterpillar cadaver in the pupal chamber made of leaves and a few strands of silk in the litter. The tough strong wasp cocoon is spun in the caterpillar’s pupal chamber. The adult wasp cuts its way out of the cocoon 32–283 days later (see rearing records in Janzen & Hallwachs, 2003), and during just about any month. This apparent variable multivoltinism is congruent with the fact that Xylophanes anubus caterpillars may be found in just about any month of the year (though in highly variable numbers) in the rain forests and cloud forests occupied by the portion of the X. anubus population used by T. laticinctus (in the ACG dry forest, X. anubus caterpillars are present only during the first 4–5 months of the 6-month rainy season). The wild-caught records of T. laticinctus suggest a flight period throughout the year, just as do the rearing records.

T. laticinctus offers a particularly good example of a parasitic wasp that does not occupy all of its host’s geographical range. Xylophanes anubus caterpillars are found feeding on Psychotria spp. throughout the understorey of ACG rain forest, lower cloud forest and dry forest. They are particularly abundant in ACG dry forest during the first 3 months of the rainy season. These dry forests range from 0 to 30 km distant from the wetter rain forests where adult T. laticinctus have been caught frequently and the ten parasitized caterpillars were found. However, no species of Thyreodon has been reared from the 490 wild-caught X. anubus caterpillars found in the ACG dry forests up until 2002, even though these were collected during rainy season months ( Janzen & Hallwachs, 2003), a time when the forest understorey in dry forest and adjacent wetter forests seem microclimatologically to be very similar. T. laticinctus is restricted to rain forest by factors other than simple presence of its host caterpillar.

Material examined: Holotype ♀, ( T. laticinctus Cresson ) MEXICO, Orizaba ( PANS) ; Holotype ♀, ( T. principalis Smith ) COSTA RICA, Cartago Prov., Cachí ( BMNH) ; lectotype ♂, ( Thyreodon zonatus Szépligeti ) BOLIVIA, Juntas ( TM) .

Non-type material: BELIZE: 1 ♀, Punta Gorda (BMNH). COSTA RICA: Alajuela Prov.: 2 ♀, Falda Este, Volcán Tenorio, Colonia Rio Celeste, Finca Magli, 400– 500 m, xi.1988 (Solis) ( INBio ); 3 ♀, same locality, iv.1988 (Soto) (UCRC); 1 ♀, Finca San Gabriel, 2 km W Dos Rios, 600 m, v.1990 (Parataxonomists) ( INBio ); 2 ♀, San Ramon, Rio San Lorencito, 800–850 m, iv– v.1987 (Solis) ( INBio ); 2 ♀, San Ramon Biological Reserve, 800 m, I–iii.1995 (Carballo) ( INBio ); 2 ♀, 2 ♂, Sector Colonia Palmareña, 9 km SW Bajo Rodriguez, 700 m, ix.1995, iv.1997 (Saborio & Carballo) ( INBio ); 7 ♀, 2 ♂, Sector San Ramon, 620 m, iv.1994 (Parataxonomists) ( INBio ); 2 ♀, Zapote, Upala, iii.1988 (Chacon) ( INBio ): Cartago Prov.: 1 ♂, Turrialba (USNM); 1 ♂, Volcán Irazú, 2–2200 m (Rodgers) (BMNH): Guanacaste Prov.: 1 ♀, 1 ♂, Guanacaste National Park, Cerro el Hacha , 400 m, v.1988 (Espinoza) ( INBio ); 2 ♀, 1 ♂, Guanacaste National Park, Estacion Pitilla, 680 m, xi.1988, v.1989, i.1991 (Gauld & Mitchell) (BMNH); 50 ♀, 16 ♂, Guanacaste National Park, Estacion Pitilla, 9 km S Sta Cecilia, 700 m, vii.1988, vii.1991, iii–v, ix–x.1992, iv.1994 (Parataxonomists) ( INBio ); 3 ♀, Guanacaste National Park, Estacion Pitilla, Finca Pasmompa, 5 km SW Sta Cecilia, 400 m, iii.1989 (Parataxonomists) ( INBio ); 1 ♀, Guanacaste National Park, Estacion Cacao, 1000– 1400 m, xii.1989, vi.1990 (Gudamuz) ( INBio ); 1 ♀, Guanacaste National Park, Estacion Maritza, 700 m, vi.1986 (Gauld) (BMNH); 9 ♀, 2 ♂, Guanacaste National Park, reared as per data listed above (Janzen & Hallwachs) (JHVC); 1 ♀, Rincon de la Vieja National Park, Las Pailas, 800 m, iii.1993 (Parataxonomists) ( INBio ); 2 ♀, Rincon de la Vieja National Park, Las Pailas, 800 m, v.1994 (Taylor) ( INBio ): Heredia Prov.: 2 ♀, Braulio Carrillo National Park, Estacion El Ceibo, 400–600 m, x.1989 (Parataxonomists) ( INBio ); 1 ♀, La Selva Biological Station, 50–150 m, iii.1988 (Soto) (UCRC): Limón Prov.: 1 ♀, Guapiles (Schaus) (USNM): Puntarenas Prov.: 4 ♀, Amistad National Park, Finca Cafrosa, Las Mellizas, 1300 m, iii, vi.1991 (Ramirez) ( INBio ); 1 ♀, same locality, iv.1996 ( Chinchilla ) ( INBio ); 1 ♀, Monteverde Reserve, San Luis, Buen Amigo, 1350 m, v.1994 ( Fuentes ) ( INBio ); 1 ♀, 1.4 km NE La Tigra, Avenida el Pizote, 1300 m, viii.1996 (Navarro) ( INBio ): San José Prov.: 2 ♀, Braulio Carrillo National Park, Estacion Carrillo, 700 m, ii.1993 (Parataxonomists) ( INBio ). GUATE- MALA: 1 ♂, Vera Paz, Senahu (Champion) (BMNH); 1 ♀, Zapote (Champion) (BMNH). PANAMA: 1 ♂, Cerro Campana, vii.1970 (Howden) (AEIC). We have also seen specimens from Colombia, Ecuador and Peru (in AEIC, BMNH).

Figures

Figures 21–26. SEM photographs of Thyreodon spp., pronotum, lateral; 21, T. whitfieldi; 22, T. laticinctus; 23, T. darlingi; 24, T. rivinae; 25, T. morosus; 26, T. walkerae.

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 3–6. Thyreodon species, whole insects, lateral, showing major colour patterns found in the genus. 3. T. atriventris. 4. T. laticinctus. 5. T. walkerae. 6. T. schauffi. Scale bar = 5 cm.

Figures 15–20. SEM photographs of Thyreodon spp. 15–16, head, anterior, showing interantennal area; 15, T. santarosae; 16, T. walkerae. 17–18, mesopleuron, lateral; 17, T. morosus; 18, T. walkerae. 19–20, propodeum, lateral; 19, T. whitfieldi; 20, T. laticinctus.