Thyreodon erythrocera Cameron, 1886

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 : 328-330

[ Thyreodon erythrocera Cameron ; Porter, 1984: 50.

Misidentification.]

[ Thyreodon erythrocera Cameron ; Gauld, 1988: 62. Misidentification.]

Fore wing length 17.2–22.6 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 sparsely 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 1.2 times its own maximum diameter; head in dorsal view with gena strongly rounded behind eye, occipital carina strong and complete, its lower end reaching hypostomal carina above base of mandible; antenna setaceous, with 55–56 flagellomeres, the 20th slightly transverse, 0.9 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 quadrately swollen, but not projecting as a crest over deep transverse U-shaped groove; epomia more or less absent; propleuron sparsely punctate, with a sharp transverse carina separating off lower corner; mesoscutum closely punctate, with broad, shallow, reticulated notauli which are confluent posteriorly, inner anterior margin of notaulus forming a low, sharp ridge; scuto-scutellar groove very deep, laterally margined by a very strongly broadened carina; scutellum rugose-punctate, convex; mesopleuron finely punctate, without a very shallow, foveolate sternaular impression; metapleuron finely punctate with a few obscure diagonal ridges; propodeum laterally slightly flattened, finely reticulate to closely punctate, dorsally rounded, without a ridge above and behind the spiracle; propodeum posterodorsally finely reticulate, centrally with a single shallow longitudinal impression. Fore leg of female rather stout, with coxa with a large 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, unusual in being more densely pubescent than most other species; hind femur slen- der, 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 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, 1.8–1.9 times as long as posteriorly deep. Male with subgenital plate small and convex, covered with dense black hair; claspers very long and tapered, the dorsal apex acute, apically obliquely truncate, the lower margin rounded; aedeagus in profile with apex up-turned, weakly inflated, rounded.

A black species with wings blue-blackish infumate. One undersized male is very dark reddish brown.

Remarks: Thyreodon sharkeyi is named in honour of Michael J. Sharkey, in recognition of his identification of thousands of large braconid wasps reared by the ACG caterpillar inventory. T. sharkeyi has been consistently misidentified as T. erythrocera Cameron. I have re-examined the holotype of T. erythrocera , from Yucatan in Mexico, and conclude that it is not conspecific with other material identified as this species by Porter (1984) and Gauld (1988). After repositioning the palpi of the holotype, which obscured the base of the occipital carina, it is clear that the occipital carina of T. erythrocera is ventrally incomplete and not complete as previously thought. Furthermore, the holotype of T. erythrocera has no trace of a carina on the lower part of the propleuron. T. sharkeyi has the lower part of the occipital carina strong and complete to the hypostomal carina, and has a pronounced carina on the lower corner of the propleuron. Like most other species of Thyreodon , T. sharkeyi has the dorsal posterior part of the propodeum acarinate, but T. erythrocera is distinctive in having a sharp carina laterally, on either side of the petiolar insertion, and diverging anteriorly before fading out about 0.3 of the way along the propodeum.

Biological notes: Thyreodon sharkeyi is the only large wasp parasitizing the caterpillars of Xylophanes turbata in the ACG dry forest ( Table 2). It finds them on both of the X. turbata food plants ( Hamelia patens and Psychotria microdon , Rubiaceae ). [84-SRNP-1045; 88-SRNP-202; 93-SRNP-807.1; 94-SRNP-3074.1; 94-SRNP-3086; 94-SRNP-3090; 94-SRNP-3098; 94-SRNP-3099; 94-SRNP-3108; 97-SRNP-2395; 97-SRNP-2731; 97-SRNP-2751; 97-SRNP-2752; 00-SRNP-7689; 00-SRNP-7891; 00-SRNP-7902.] It was reared from 2.2% of 1000 X. turbata caterpillars collected in the third to fifth (last) instars and from none of the 187 caterpillars collected in the first or second instars. T. sharkeyi was also reared from 3.3% of 214 third to fifth instar caterpillars of Xylophanes pluto feeding on the same two food plants. It was not reared from any of 494 caterpillars of Xylophanes anubus , X. juanita , X. tersa , X. libya , X. ceratomioides , X. maculator , X. chiron or X. porcus feeding on these same two food plants at the same time in the same place (none of these is parasitized by any other Thyreodon in the ACG dry forest). T. sharkeyi has not been reared from any of 126 caterpillars of Xylophanes pluto feeding on its third usual food plant, Lindenia rivalis (Rubiaceae) , in the ACG dry forest. We conclude that T. sharkeyi is a specialist on X. turbata larvae but also takes X. pluto larvae when they are feeding on the same food plant as X. turbata . It either ignores the eight other species of (equal-sized) Xylophanes feeding on the same food plant at the same time, or fails to develop in these eight conspecifics.

T. sharkeyi spin the smallest and most slender ovoid cocoons of all the species of Thyreodon reared to date. The cocoons are spun in the caterpillar pupal chamber, which is a nest or basket of litter leaves lightly tacked together with silk.

A single Cidaphus rostratus ( Ichneumonidae : Mesochorinae ) hyperparasite was reared from a presumed T. sharkeyi (93-SRNP-1883). The host caterpillar, X. turbata , was collected as a third instar on 9 June 1993 while feeding on Hamelia patens . The newly eclosed hyperparasite cut an exit hole in the anterior end of the T. sharkeyi cocoon on 6 April 1995. This date is 1 month before the beginning of the rainy season and 2 years after spinning its cocoon. During these 2 years, the cocoon was in a dry bottle at ambient temperature inside a non-airconditioned house in the ACG dry forest. Two other cases of this species of hyperparasitoid involved 1–2 years in the cocoon as well (see Thyreodon rufothorax ).

Material examined: Holotype ♀, COSTA RICA, Guanacaste Prov., Santa Rosa National Park , 300 m, vi.1984 (Janzen & Hallwachs) ( BMNH) . Paratypes: COSTA RICA: Guanacaste Prov.: 1 ♀, Santa Rosa National Park , 300 m, vii.1984 (Janzen & Hallwachs) ( BMNH) ; 8 ♀, 8 ♂, Guanacaste National Park , reared as per data listed above (Janzen & Hallwachs) ( JHVC) . MEXICO: Nuevo León: 1 ♀, Pedro Iturbide , 32 km W Linares, x.1962 (Townes) ( AEIC) : Sonora: 1 ♀, 1 ♂, Cananca , viii.1974 (Erickson) ( AEIC) ; 1 ♀, ‘ N. Sonora’ (Morrison) ( BMNH) .