AGAONIDAE Walker, 1846

Farache, Fernando H. A., Rasplus, Jean-Yves, Azar, Dany, Pereira, Rodrigo A. S. & Compton, Stephen G., 2016, First record of a non-pollinating fig wasp (Hymenoptera: Sycophaginae) from Dominican amber, with estimation of the size of its host figs, Journal of Natural History 50, pp. 2237-2247 : 2240-2244

Family AGAONIDAE Walker, 1846

Subfamily SYCOPHAGINAE Walker, 1875 Idarnes Walker, 1843 Idarnes thanatos Farache, Rasplus, Pereira and Compton , sp. nov. urn:lsid:zoobank.org:act:0A8B0B2A-3E43-4516-AA2D-CBC390BFB385

Figure 1

Derivation of name

The specific name is derived from the Greek ‘ θάνατος ’, the god of death, in reference to it being an extinct taxon.

Diagnosis

Body colour mostly black, with faint metallic reflection. Antenna with two anelli. Supraclypeal area wider than torulus diameter. Mesoscutum and mesoscutellum reticulate. Postmarginal vein 1.2× as long as stigmal vein. Ovipositor sheaths 1.1× as long as body.

Description

Size and colour. Body length (excluding ovipositor) 1.1 mm. Length of ovipositor sheaths 1.2 mm. Body colour mostly black, with faint metallic reflection, mostly green and orange, at least on mesosoma in dorsal view. Antennae dark brown. Legs yellow brown. Wings hyaline, submarginal vein dark brown, marginal, postmarginal, and stigmal veins light brown.

Head. Antenna with 13 antennomeres including two anelli; antennal formula 11263. Scape 1.4× as long as pedicel. Funicular segments 1.0 – 1.4× as long as wide. Clava well delimited, with three laterally compressed flagellomeres (compression probably related to post mortem alteration). Antennae inserted just above the lower line of compound eyes. Head transverse, 1.3× as wide as high. Head sculpture reticulated, at least close to vertex. Supraclypeal area wider than torulus diameter. Clypeal margin unilobed.

Mesosoma. Pronotum longer than high in lateral view. Mesoscutum and mesoscutellum reticulate. Notauli complete. Mesoscutellar – axillar complex with straight axillular grooves and transverse frenal sulcus, delimitating a square mesoscutellum. Mesoscutellum 1.1× as long as wide. Propodeum length 3.5× propodeal spiracle diameter. Postmarginal vein 1.2× as long as stigmal vein. Protibia with a bifurcated tibial inner spur. Metatibia with two tibial inner spurs.

Metasoma. Suboval. Ovipositor sheaths 1.1× as long as body. Ovipositor teeth concentrated at the distal extremity of ovipositor. Teeth heterogeneously distributed and of variable length, shorter at the tip of the ovipositor.

Measurements (mm). Head: L 0.13 W 0.28 H 0.22; Mesosoma L 0.47; Metasoma L 0.51. Scape L 0.17; Pedicel L 0.05; F1 L 0.03 W 0.03; F2 – 6 L 0.04 W 0.03; Clava L 0.11 W 0.05; Eye L 0.18 H 0.22; Profemur L 0.2 W 0.05; Protibia L 0.15 W 0.03; Protibial inner spur L 0.05; Metafemur L 0.18 W 0.05; Metatibia L 0.17 W 0.03; Metatibial inner spur 1 L 0.04; Metatibial inner spur 2 L 0.03.

Remarks

The (unnamed) specimen was used previously in Cruaud et al. (2011a) for calibration of a molecular clock analysis. Idarnes thanatos sp. nov. belongs to the I. carme species-group, based on the following characters: (1) postmarginal vein longer than stigmal vein, (2) ovipositor longer than body, (3) clypeal margin unilobed, (4) head sculpturation heterogeneous (but visualization of this character was difficult due to the preservation of the fossil), and (5) ovipositor teeth concentrated at the distal extremity of the ovipositor, with a heterogeneous distribution and of variable length. We are confident that I. thanatos sp. nov. does not belong to any known extant Idarnes species. This putatively extinct species can be easily distinguished from other known Idarnes carme sp. gp species by a combination of characters: (1) the presence of two anelli (rather than one) and (2) its relatively short ovipositor.

Holotype

Female, MZSP, amber from the Dominican Republic. The specimen occurs in a small, clear piece of amber measuring 3.9 mm in length, 2.5 mm in height, and 1.5 mm in width (thickness). The amber piece is attached to a glass holder and mounted on an entomological pin to facilitate handling and image acquisition. The specimen is deposited in the Hymenoptera collection at Museu de Zoologia, Universidade de São Paulo, São Paulo, Brazil.

Estimation of host fig size

Body characters and fig diameter across extant Idarnes species and their hosts were positively correlated ( R 2 = 0.68 – 0.76, p ≤ 10−8, Table 1). This pattern was also observed when we used maximum fig size instead of median fig sizes, which confirmed the robustness of the median as a measure of size. Ovipositor sheath length was the body

Model Slope R 2 t value Prob. Ovipositor sheath length ~ fig size 2.9 ± 0.3 0.76 9.69 <10−9 Body length ~ fig size 0.5 ± 0.06 0.69 8.28 <10−8 Ovipositor/body ~ fig size 1.3 ± 0.15 0.70 8.43 <10−8

character best explained by fig diameter ( Table 1, Figure 2 ). The fitted value of median fig diameter for the ovipositor sheath length of I. thanatos sp. nov. ( OL = 1.2 mm) was 0.61 cm ( CI 95% = 0.22 – 1.01 cm) ( Figure 2 ). Among the 31 studied fig wasp species, 20 occurred in figs with the same diameter range as the 95% CI calculated for the diameter of the putative host of I. thanatos , and comprised the Ficus americana and F aurea complexes, some varieties of the F. pertusa complex, F. citrifolia , F. cestrifolia , F. colubrinae , F. eximia , F. hartwegii and F. mariae . More specifically, the body length and ovipositor sheath length of I. thanatos are similar to those of three Idarnes species currently associated with the F. americana complex.

Figures

Figure 1. Idarnes thanatos sp. nov. female. (a) habitus in lateral view; (b) antenna; (c) detail of antenna; (d) mesosoma in dorsal view; (e) detail of profemur and protibia; (f) wings.

Figure 2. Linear regression between Idarnes carme sp. gp ovipositor sheath lengths and median host fig diameters. Lines represent fitted model (red) and fig diameter ±95% CI (blue) for a 1.2 mm ovipositor sheath length, which represents the ovipositor sheath length of I. thanatos sp. nov. Each point represents a different fig wasp species and the fig diameter of its host species.