Melanosphecia paolo Skowron Volponi, 2019

Skowron Volponi, Marta A., 2019, A new species of spectacular spider wasp mimic from Thailand is the first representative of the genus Melanosphecia Le Cerf 1916 (Lepidoptera: Sesiidae: Osminiini) to be filmed in the wild, Zootaxa 4695 (3), pp. 295-300 : 296-299

Melanosphecia paolo Skowron Volponi sp. nov.

( Figs 1–3 )

Type material Holotype ♂, pinned ( Fig. 2 ). Original labels: “ THAILAND: Phetchaburi. 02 II 2019. Skowron Volponi M.A. Missing hind leg at time of collection.”; “ Holotype, Melanosphecia paolo sp. n., des. Skowron Volponi MA 2019”; “Genitalia slide ♂, No. MSV-18” Will be deposited in the Natural History Museum in London.

Description. Alar expanse 29 mm, body length 15 mm

Head: antennae black with blue sheen, beige scales form a thin longitudinal stripe on exterior edge gradually widening towards tip, beige scales on margin of each antennae segment ventrally, larger, black and white scales at antennae base; frons smooth-scaled, black with metallic blue sheen; vertex covered with elongated black scales with metallic blue sheen, small patch of smooth white scales adjacent to complex eyes; labial palpi long and upturned, silvery black and bright white: elongated white scales at base, white scales mixed with black in proximal half ventrally and dorsally, in distal half white scales interiorly, ventral distal half black, tip black with several creamy white scales; pericephalic hairs black and white; complex eyes matt dark brown; proboscis long and functional, orange brown.

Thorax: patagia black with metallic blue/green sheen, entire thorax covered with black scales with strong metallic blue sheen, minute white hairs on mesothorax; tuft of white mixed with some black hairs laterally below wing insertion protruding onto abdomen.

Legs: fore coxa black with blue sheen, several white scales near base; fore femur, tibia and tarsi black with blue sheen, smooth-scaled dorsally and with elongated scales forming two tufts on ventral side of femur and tibia; midlegs black with blue sheen, some smooth white scales ventrally on tibia, elongated black with blue sheen mixed with white scales at distal end of tibia dorsally, spurs black and white; hind legs long, black with blue sheen, smooth white scales interiorly on proximal half of tibia, ventrally smooth, two very peculiar tufts of elongated scales, bluish black with some white, which form an imitation of two erected spines on the exterior side of the hind tibia, whereas interiorly on distal half of tibia and 1 st tarsomere the scales are uniformly elongated, smooth-scales ventrally and dorsally between exterior and interior tuft on tibia, as well as between the two tibial “spines”, tarsomeres 2–5 and distal end of 1 st tarsomere smooth-scaled.

Forewing: almost entirely opaque with two very narrow longitudinal transparent areas from base; black with intense dark blue/purple or greenish sheen depending on the angle of light rays, lighter blue scales along cubital and subcostal veins from base.

Hindwing: almost entirely transparent but wing membrane tawny; veins, discal spot and cells between veins CuA 2 and CuA 1 covered with black scales with blue sheen (leaving only a small transparent spot in these cells); smooth white scales on inner margin in basal half; cilia black.

Abdomen: dorsally black with dark blue/greenish sheen; sternites black with blue sheen and thin white bands on each posterior margin.

Male genitalia ( Fig. 3 ): Valvae long and upturned, narrowed distally, densely covered with long setae. Tegumen narrow and slightly arched, uncus with a ring of long setae at tip. Saccus short, blunt-ended. Aedaegus simple, 1 length of valva.

Female unknown.

Variability. The individual filmed in 2017 was significantly smaller than the holotype.

Differential diagnosis. From M. auricollis , M. paolo sp. nov. differs primarily in the lack of a large purple patch on the hindwing and the colouration of antennae, labial palpi and head (rufous orange in the species compared), the valva of male genitalia are slightly narrower and more elongated in M. paolo sp. nov.; from the Moluccan M. dohertyi in the overall body colouration (black-brown in species compared), especially of labial palpi and antennae (lack of rufous scales in M. paolo sp. nov.). From the New Guinean species, M. paolo sp. nov. differs in the following: from M. atra in the lack of red scales on labial palpi and antennae, colouration of thorax and abdomen ventrally, as well as of forecoxa, forewing and cilia (brown-black in M. atra ); from M. funebris , in the lack of rufous scales on labial palpi, forelegs and tegulae, white or grey scales on mid and hind tarsi, as well as the hyaline-yellow colouration of the hindwing (hyaline-white in M. funebris ). Moreover, M. paolo sp. nov. has hind leg tufts in the form of two erected “spines” ( Fig. 1 , Suppl. video), a feature which seems to be unique for this species, however only pinned specimens of all the remaining Melanosphecia species are known and it is difficult to determine the exact conformation of their hind leg tufts as it appears on live individuals.

Interestingly, the male genitalia are very similar to those of Heterosphecia bantanakai , although the two sesiids are completely different in external morphology and their COI sequences differ by 10%.

Habitat and conditions of occurrence. Pebbly river bank surrounded on one side by mixed plantations and the other by a semi-evergreen rainforest. In 2017 seen on a hot, sunny day at 1:30 pm, air temperature was 32°C. In 2019 seen once on a hot sunny day (34°C) around 12:00 and the second time on a hot cloudy day with only a bit of sunshine at 3:30 pm (35°C).

Behaviour. M. paolo sp. nov. was found mud-puddling (Suppl. video: time code 00:23–02:12), a behaviour of sucking up liquids from moist substrate recently observed for a number of Oriental Sesiidae ( Gorbunov, 2015; Quicke et al., 2018; Skowron et al., 2015; Skowron Volponi & Volponi, 2017, 2018), on a river bank. It landed on moist rocks, sometimes surrounded by algae ( Fig. 1 ). When puddling, it would fly from one rock to another in a rugged flight (Suppl. video TC 02:41–03:00), in a similar manner to Pompilidae wasps approaching their burrows. It was observed ejecting excess water during puddling, which indicates it is puddling for salt or other minerals and not just for the moisture. In flight, the sesiid arches its abdomen which gives it an even more pompilid wasp-like appearance (Suppl. video: TC 03:01–03:43). This clearwing moth actively uses the long hind legs for locomotion or to cling on to a rock during puddling (Suppl. video: TC 01:51–02:12), in contrast to, for example, Heterosphecia pahangensis Skowron, 2015 (a species also belonging to the Osminiini tribe), whose hind legs are dysfunctional in terms of locomotion. It rests with its wings folded back against its body.

DNA barcode analysis. A 648 bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) was sequenced (GenBank accession number MN514946 ) and it confirmed placement of M. paolo sp. nov. within the Osminiini tribe, however no other species of the Melanosphecia genus have been barcoded to date, thus comparisons were not feasible. From published records, the M. paolo sp. nov. COI sequence revealed highest identity with Heterosphecia pahangensis Skowron (8.4% divergence), H. bantanakai Arita & Gorbunov (10% divergence), Pyrophleps ellawi Skowron Volponi, 2017 (10.3% divergence) and P. vitripennis Arita & Gorbunov (11.1% divergence).

Etymology. I dedicate this species to my husband, Paolo Volponi, a brilliant filmmaker and clearwing moth enthusiast, whose help and assistance in the field have been crucial in the studies of this and many other Sesiidae species.

Figures

FIGURE 1 Melanosphecia paolo Skowron Volponi sp. nov., two individuals mud-puddling, in 2017 (top left) and 2019. Photographs taken by Marta Skowron Volponi & Paolo Volponi.

FIGURE 2 Melanosphecia paolo Skowron Volponi sp. nov., ♂ holotype, 1—dorsal view, 2— ventral view after removing abdominal segments for genitalia analysis.

FIGURE 3 Melanosphecia paolo Skowron Volponi sp. nov., male genitalia. Top right corner: fractured saccus before the cover slip was placed.