Meteorus restionis Shaw and Jones, 2011

Barrantes, Gilbert, Triana, Emilia, Shaw, Scott R. & Jones, Guinevere Z., 2011, Characteristics of the cocoon and natural history of the gregarious Meteorusrestionis sp. n. (Hymenoptera, Braconidae, Meteorinae) from Costa Rica, Journal of Hymenoptera Research 20, pp. 9-21 : 10-12

Meteorus restionis Shaw and Jones sp. n.

Fig. 1

Holotype

female (point-mounted), COSTA RICA: San José, UCR campus, 1100 m, 1 October 2007, E. Triana and G. Barrantes, emerged from silk cocoons found on Monstera vine growing on Cordia tree surrounded by mowed grass. Deposited in ESUW.

Paratypes.

16 females, 6 males, same data as holotype, deposited in ESUW; 5 females, 2 males, same data as holotype, deposited in MZCR.

Diagnosis.

Mandible strongly twisted, second tooth directly behind first tooth in lateral view; ocelli smaller than OOD, ocello-ocular distance 1.2x ocellar diameter; occipital carina complete; wing membrane clear; vein r ½ length of 3RSa; propodeum areolate-rugose; hind coxa finely rugulose; first metasomal tergite without dorsopes; ventral borders of first tergite joined completely along basal ½ of segment; tergum 2 black laterally, medially with white narrow hourglass-shaped figure.

Description (holotype).

Body length = 4.1 mm ( Fig. 2A ).

Color ( Fig. 2A ). Body mostly yellowish brown except head orange,compound eye silver,and other parts of body with dark contrasting markings as follows: flagellum and pedicel dark brown; scape and pedicel orangish brown infused with dark brown; ocellar triangle black; dorsal margin of pronotum with black band; lateral lobes of mesonotum and scutellum dark brown to black; mesonotum medially and scutellar disc yellow; metanotum and propodeum black; apical ½ of hind coxa dark brown to black; hind femur apically, hind tibia, and hind tarsi dark brown; wing membrane clear; wing venation and pterostigma dark brown; metasomal tergites 1-3 black dorsally except petiole yellowish white basally in dorsal view, petiole entirely white ventrally, and tergum 2 medially with white narrow hourglass-shaped figure; ovipositor and sheaths dark brown.

Head ( Figs 1 and 2B ). Antenna with 32 flagellomeres; flagellar length/width ratios as follows: F1 = 3.5; F2 = 3.3; F3 = 3.2; F28 = 2.5; F29 = 2.5; F30 = 2.5; F31 = 2.5; F32 (apical flagellomere) = 4.0; tip of apical flagellomere acutely pointed; head 1.2 × wider than high, head height 1.4 × eye height; eye small but protuberant, slightly converging ventrally in anterior view; maximum face width 1.1 × minimum face width; minimum face width 1.5 × clypeus width; malar space length 1.1 × mandible width basally; ocelli smaller than OOD, ocello-ocular distance 1.6 × ocellar diameter; lower margin of clypeus with fine rugulose wrinkles; mandible strongly twisted; occipital carina complete; vertex, in dorsal view, descending vertically behind lateral ocelli.

Mesosoma. Notauli rugulose, not distinct, and mesonotal lobes not well-defined; scutellar furrow with 1 median carina; mesopleuron polished, punctate; sternaulus weakly rugulose, broad but not long; propodeum areolate-rugose, median depression absent.

Legs. Hind coxa dull, weakly rugulose; larger hind tibial spur about 0.4x as long as hind basitarsus length; tarsal claw with a small blunt basal tooth, strongly curved.

Wings. Forewing length 3.9 mm; vein m-cu amtefurcal; second submarginal cell of forewing slightly narrowed anteriorly; vein r 0.5 × length of 3RSa.

Metasoma. first metasomal tergite without dorsopes; ventral borders of first tergite joined completely along basal ½ of segment; first tergite dorsally longitudinally costate on apical half beyond spiracles, costae slightly convergent posteriorly; ovipositor short, thick at base, 1.6 × longer than first tergite.

Variation, paratype females.

Other females as in holotype except body length 3.9-4.2 mm; forewing length 3.9-4.0 mm; antennae with 31-32 flagellomeres.

Variation, paratype males.

Similar to females except body length 3.9-4.0 mm. Antenna with 31-33 flagellomeres. Body color is similar to females except the white medial pattern on tergum 2 is broader and more variable in shape.

Comments.

Specimens of Meteorus restionis sp. n. were identified by SRS using the key to Costa Rican Meteorus species by Zitani et al. 1998. They key, with some difficulty, to couplet 11, where they are nearest to Meteorus dos Zitani. This species is distinct from Meteorus dos by having smaller eyes, broader face, less convergent eyes, and frons without a strong median tubercle. At couplet 10 Meteorus restionis sp. n. is difficult to key because the sculpture on tergum 1 is somewhat intermediate between the sculpturing patterns seen in Meteorus alejandromasisi Zitani and Meteorus dos Zitani. Although the longitudinal costae of the first metasomal tergite are mostly rather parallel (as in Meteorus alejandromasisi ) they do converge somewhat posteriorly, so will key onward to couplet 11 near Meteorus dos . The only other Meteorus species known to reside on the UCR campus is Meteorus oviedoi ( Shaw and Nishida 2005). Although somewhat similar in overall color pattern, Meteorus restionis sp. n. differs from Meteorus oviedoi by its shorter OOD and larger ocelli (OOD, ocello-ocular distance, 1.2 × ocellar diameter in Meteorus restionis and 1.6 × ocellar diameter in Meteorus oviedoi ), and by its very different cocoon-forming behavior (described below).

Etymology.

The specific epithet is from the Latin restionis, meaning “rope-maker” as a reference to the cocoon-forming behaviour of this Meteorus species.

Distribution.

All the type specimens were reared from gregarious cocoons collected on campus of the University of Costa Rica, Montes de Oca, San Pedro, San José in Costa Rica. This is the only location where the species has been found, although the associated plants are widespread.

Characteristics of the cocoons.

Both groups the cocoons were suspended from a single cable ( Fig. 3A ), whose entire lengths were 72 cm and 63.5 cm respectively. This cable was formed by individual threads that twisted on each other and intertwined like a rope. In both cases the independent threads were attached to the lower surface of a leaf of a fruit salad vine plant ( Monstera deliciosa , Araceae ) and they intertwined, forming a single cable, about 5 cm beneath the leaf surface. Both fruit salad vine plants climbed trunks of Cordia eriostigma trees ( Boraginaceae ) which were separated by 5 m. One of the cables branched off at 12.5 cm from the end, i.e. dividing the main cable in two; one branch having 19 and the second 11 cocoons. The cable of the other group did not branch and had 49 cocoons. No sign of the possible host larva was found in either case. The cocoons in both cases were grouped at the last section of the suspended cable (14 and 17 cm respectively), and the distance between contiguous cocoons varied from 29 to 0 mm (0 mm when two cocoons were opposite to each other at the same level of the cable). The distance between cocoons decreased toward the tip of the cable (basal section: mean = 26.83 mm, SD = 35.49 mm, N = 14; middle section: mean = 1.65 mm, SD = 2.21 mm, N = 13; distal section: mean = 1.58 mm, SD = 2.21 mm, N = 13).

The cocoons were dark-brown and had an ovoid shape. The posterior end was wider than the anterior end which was blunt, rather than ending with a nipple-like final portion as the cocoons of some other species ( Figs 3B-C ). All cocoons were attached nearly perpendicularly by the posterior extreme to the suspended cable, rather than to an individual thread ( Figs 3A , 4A-B ). Prior to emergence the wasps cut a neat, circular cap at the anterior end of the cocoon, and the cap remained attached by some threads to the rest of the cocoon ( Fig. 5A ). Inside the cap there was a yellow soft-pad against which the head of the pupating wasp “rested” inside the cocoon ( Fig. 5A-B ).

Thread resistance.

The cable was very resistant to breaking. One of the cables resisted a weight of 44.17 g before breaking. What looked like a single thread, constructed possibly by an individual larva, consisted of two relatively thick threads when observed under the compound microscope and each of these threads were formed by multiple very thin fibrils ( Figs 6A-B ). Additionally, the fibrils and threads were glued together and at irregular intervals along the cable with large clogs of a resin-like substance that bound several threads together ( Fig. 6C ).

Wasp emergence and sex ratio.

All but one wasp emerged from the first group of cocoons collected (cocoons of the other group were empty). Within this group 22 wasps were females and eight were males. This sex ratio significantly differed from a 1:1 proportion (p = 0.011, Binomial test). Pupae were not hyperparasitized; the only wasp that did not emerge was completely developed and the cause of its failure to emerge was unknown.

Figures

Figure 1. Meteorus restionis sp. n., lateral view. A Detail of head and anterior mesosoma B Detail of mesosoma showing mesopleuron and sternaulus sculpture C Middle and hind coxa sculpture D Apex of antennal flagellum E Hind tarsal claw with basal lobe; part of ovipositor sheath on left.

Figure 2. Female Meteorus restionis. A Pattern of coloration B Head details.

Figure 3. Group and shape of cocoons of Meteorus restionis. A Distal section of a hanging cable showing 20 of the 49 cocoons in the group. Note the nearly perpendicular position of the cocoons relative to the cable B Individual cocoon; note the lack of the nipple-like anterior end typical in cocoons of other species C Detail of the anterior end showing its shape and the very fine cut produced for the wasp inside prior to its emergence.

Figure 4. Cocoons attached by the posterior end to the cable. A A circle of relatively thick threads secure the cocoon to the cable B Cocoon attached to the cable.

Figure 5. Cap of the cocoon and pupating wasp. A The cap finely cut by the wasp hangs from a few threads to the rest of the cocoon. The bottom of the cap is covered by a soft yellowish pad B Position of the pupating wasp inside the cocoon; the top of the wasp's head rests on the pad.

Figure 6. Details of the threads and resin-like clog. A A pair of relatively thick threads, possibly produced by a single larva, glued together B The threads consist of a large number of fibrils C Clog of a resin-like substance. Clogs bind together threads along the cable.