Osmanthedon domaticola Agassiz & Kallies, 2018

Agassiz, David & Kallies, Axel, 2018, A new genus and species of myrmecophile clearwing moth (Lepidoptera: Sesiidae) from East Africa, Zootaxa 4392 (3), pp. 588-594 : 590-592

Osmanthedon domaticola Agassiz & Kallies spec. nov.

( Figs 1–6 )

Material examined. Holotype ♂ ( Fig. 1 ). [Tanzania] Sanya | 3.iii.1961 | B. Hocking, CIE Coll. No. 17818, BM Genitalia slide No. 33632 (BMNH). Paratypes (1♂, 4♀): 1♂ KENYA, Rift Valley, Laikipia, Mpala Research Centre, 1700 m; 0˚17’27”N 36˚52’53”E, larva in domatium of Acacia drepanolobium [= Vachellia drepanolobium ], 7.xi.12, emerged 29.i.2013, Agassiz, Beavan, Heckford & Ngugi; 1♀ KENYA, Rift Valley, Mpala Ranch, 1800 m, 0˚17’N 36˚52’E, larva in domatium of A. drepanolobium [= V. drepanolobium ], emerged 4.xii.2009, D. J. L. Agassiz ( Fig. 2 ) (NMK); 1♀ KENYA, Central, 10 km S of Naro Moru, 2060 m, 0˚16’53”S 37˚0’39”E, larva in domatium of A. drepanolobium [= V. drepanolobium ], emerged 15.xii.2009, D. J. L. Agassiz; 1♀ same data, emerged 7.i.2010 (ZMHB); 1♀ KENYA, Rift Valley, Naivasha, 1800 m, Lake Road South, larva in domatium of A. drepanolobium [= V. drepanolobium ], emerged 15.xii.2009, D. J. L. Agassiz.

Etymology. Derived from Latin, meaning dwelling in a domatium.

Description. Male, holotype ( Fig. 1 ). Alar expanse 15 mm, antenna length 3.8 mm, body length 8.5 mm.

Head. Labial palpus predominantly white, second palpomere with black bristly scales distally, apical palpomere black at tip; frons metallic grey. Antennae thick and distinctly clubbed, apically abruptly ending, not tapering; ventrally covered with short ciliae, which are slightly longer than the width of the flagellum.

Thorax. Legs black with white hair-like scales, coxae black, with broad white margins, tibiae and tarsomeres with white distal margins. Forewing with external transparent area (ETA) consisting of four cells between R5 and Cu1, the one between M3 and Cu1 being very small, all covered densely by semitransparent scales; apical area black, covered with individual white to grey scales between the veins, gradually giving way to ETA; fringe dark grey. Hindwing transparent; discal spot absent; fringe dark grey, white at anal margin.

Abdomen. Black, sternite 4 white, sternite 5 partially covered in white scales, anal tuft yellow ventrally.

Male genitalia ( Figs 4, 5 ). Vinculum and tegumen tightly fused, without any distinct gnathos lobes, tegumen ventrally membranous, valva with a soft bulbous crista near the centre of valva; base of the valva with welldeveloped scale or sensilla sockets; ventral margin of the valva with a distinct processus half way; phallus with a distinctly hooked and large cornutus and small scobinate corona penis.

Female ( Fig. 2 ). Similar to male, but slightly larger and transparent areas less densely covered by semitransparent scales. Antenna smooth; black dorsally, each segment ventrally with a row of yellow scales, transparent areas covered in semitransparent scales. Anal tuft only laterally developed, terminal segment dorsally and ventrally only with very short scales.

Female genitalia ( Fig. 6 ). Antrum very short, ductus seminalis close to ostium, ductus bursae close to antrum distinctly expanded.

Diagnosis. This species is superficially similar to some species of the tribe Osminiini , in particular the genus Osminia . In Africa, the latter is represented only by Osminia namibiana Kallies, 2004 which was described from the Brandberg in Namibia. However, Osminia species lack or have extremely short ciliae on the ventral surface of their antennae and the valva and uncus of the male genitalia are covered in simple setae.

Biology. The larvae of Osmanthedon domaticola spec. nov. live within domatia (ant galls) and are closely associated with ants on Vachellia drepanolobium (Harms ex Sjöstedt) P.J.H.Hurter (Fabaceae) . The domatium is used by aggressive ants of the genus Crematogaster Lund. Three species occur where the larva has been found, C. mimosae Santschi , C. nigriceps Emery and C. sjostedti Mayr , but it is not clear which ones are associated with this Sesiid species. The larva lives beneath a tough dome shaped membrane about 7 mm in diameter ( Fig. 7 ). There are small holes around the base of the dome, insufficient to allow an ant to get through, but around the dome amongst some frass are the head capsules shed by the larva at its various instars. Instead of this frass being loosely dispersed it is held against the wall of the domatium as though covered in some kind of secretion. Before pupation, the larvae gnaw a ring enabling the pupa to break out before eclosion ( Fig. 8 ). All specimens known to date were collected at altitudes between 1700 and 1800 m.

Distribution. Kenya and Tanzania.

Figures

FIGURES1–6. Osmanthedon domaticola gen. etspec.nov. 1.Male,holotype (alar expanse15 mm).2. Female,paratype (alar expanse 18.5 mm). 3. Venation. 4. Male genitalia, phallus removed. 5. Male genitalia, phallus.6. Female genitalia.

FIGURES 7, 8. Osmanthedon domaticola gen. et spec. nov., 7. Domatium, opened, with membranous structure under which the larva lives.8. Domatium with exposed exuvia after exclusion.