Thyreodon whitfieldi, 2004

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 : 323-324

7. THYREODON WHITFIELDI GAULD SP. NOV.

Fore wing length 21.5–24.0 mm; clypeus weakly convex, with apex flared outwards, 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 regularly coarsely and closely punctate; 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 1.4–1.5 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 62–68 flagellomeres, the 20th slightly transverse, 0.6–0.7 times as long as broad, the subapical flagellomeres with setae that are shorter 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. 21 ); epomia weak but discernible on upper part of pronotum; propleuron sparsely punctate, with lower corner rounded, peripherally weakly impressed; mesoscutum punctate, with broad, shallow, reticulated notauli which are confluent posteriorly, inner anterior margin of notaulus forming a moderately high, sharp ridge; scuto-scutellar groove very deep, long, laterally margined by very strongly raised carinae; scutellum closely punctate, convex; mesopleuron moderately closely punctate, with a slightly more coarsely sculptured diagonal band from lower hind corner to near upper end of epicnemial carina, without a sharp sternaular impression; metapleuron finely punctate with weak diagonal ridges; propodeum laterally slightly flattened, finely rugose, with upper anterior part convexly rounded, without any trace of a sharp ridge above and behind 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 slightly flattened with a low bluntly rounded protuberance behind trochanteral insertion, with 5th tarsomere 1.2–1.3 times as long as the 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 quite stout, about 5 times as long as maximally deep; hind tarsus of male with dense, unusually long pubescence ventrally. Fore wing with abscissa of Cu 1a between Cu 1b and 2 m-cu 0.9– 1.0 times as long as abscissa of Cu 1 between cu-a and 1 m-cu. Metasoma with tergite I slender, anteriorly slightly laterally compressed; tergite II, in lateral view, 1.6–2.0 times as long as posteriorly deep. Male with subgenital plate small and convex, covered with dense coarse black hair; claspers of moderate length, the dorsal apex produced into a short spine-like projection, the lower margin barely angulate before apex ( Fig. 55 ); aedeagus in profile with apex up-turned, strongly inflated, rounded.

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

Remarks: Thyreodon whitfieldi is named in honour of James B. Whitfield, in recognition of his identification of tens of thousands of tiny black microgastrine braconid wasps reared by the ACG caterpillar inventory. T. whitfieldi is most easily distinguished from most Thyreodon species by its very striking colour pattern, 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, and this is T. laticinctus . These two species are extremely similar and have been confused in all collections to date, as well as when it is seen flying. However, they differ subtly but consistently. T. whitfieldi has the propodeum with the upper anterior part evenly convexly rounded, without any trace of a sharp ridge above and behind the spiracle, has tergite II, in lateral view, 1.6–2.0 times as long as posteriorly deep, and has the hind femur stouter. T. laticinctus has the propodeum with a low, sharp (and often polished) ridge above and behind the spiracle, has tergite II, in lateral view, 2.2–2.5 times as long as posteriorly deep, and has the hind femur slender, about 6 times as long as deep. They also differ in the form of the antennae of the female. Those of T. whitfieldi have consistently more flagellomeres (63–68) than do those of T. laticinctus (51–55), have the central flagellomeres more transverse (0.6–0.7 times as long as broad) and the apical ones with shorter setae. The apical flagellomeres of T. laticinctus have setae that are longer than the diameter of the flagellomere. The apex of the aedeagus of T. whitfieldi is much stouter and more rounded than that of T. laticinctus , and the dense pubescence on the hind tarsus is slightly longer and more conspicuous.

Biological notes: Thyreodon whitfieldi is only known to occur in the ACG. Individuals have been collected in a wide range of rain forest and cloud forest between about 500 and 1400 m. Although this species occurs well within the area of the ACG caterpillar rearing programme, it has only been reared on a single occasion. A single female has been reared in Rincon rain forest from the larva of Xylophanes chiron Drury found feeding on Psychotria berteriana (Rubiaceae) [02-SRNP-21531]. The larva was collected in December, and the ichneumonid emerged from its cocoon the following March. Rearing 285 other specimens of X. chiron did not produce any other specimens of Thyreodon .

Material examined: Holotype ♀, COSTA RICA, Guanacaste Prov., Guanacaste National Park, Estacion Cacao, SW side of Volcán Cacao, 1000–1400 m, v–vi.1991 (Parataxonomists) ( INBio ). Paratypes: COSTA RICA: Alajuela Prov.: 1 ♀, Finca 6, Rincon rain forest, ACG, reared, data given above (Perez) (JHVC); 1 ♀, Sector San Ramon de Dos Rios, 620 m, iv–v.1996 ( Quesada ) ( INBio ): Guanacaste Prov.: 5 ♀, 1 ♂, Guanacaste National Park, Estacion Maritza, on W side Volcán Orosi, 560 m, v, x.1988, iv–vi.1989 (Gauld & Mitchell) (BMNH); 1 ♂, Guanacaste National Park, Estacion Pitilla, 9 km S Sta Cecilia, 700 m, iii.1990 (Rios, Moraga & Blanco) ( INBio ); 3 ♀, Guanacaste National Park, Estacion Cacao, 1000–1400 m, iii– viii.1990, v–vi.1991 (Parataxonomists) ( INBio ); 1 ♀, Guanacaste National Park, Estacion Cacao, Arenales, 1100 m, vi.1990 (Parataxonomists) ( INBio ); 1 ♀, Hda Santa Maria, 750 m ( INBio ) ( INBio ); 7 ♀, 1 ♂, Rincon de la Vieja National Park, Las Pailas, 800 m, viii– ix.1992, vii, x.1993, iv, vi.1994 ( Garcia ) ( INBio ); 2 ♀, same locality, 4 km S Cerro Braun, 1100 m, iv–v.1996 (Masis & Espinoza) ( INBio ); 1 ♀, same locality, 2.5 km S Cerro Braun, 1250 m, iv.1996 (Masis) ( INBio ); 1 ♀, same locality, 2 km S Cerro Braun, 1000–1400 m, vii.1996 (Ugalde) ( INBio ); 1 ♀, Rincon de la Vieja National Park, Las Pailas, 800 m, iv.1994 (Taylor) ( INBio ).

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.