Alaena margaritacea, Eltringham, 1929, Eltringham, 1929

Terblanche, Etienne, 2021, Observations on the mating behaviour and related copulatory anatomy of Alaena margaritacea Eltringham, 1929 (Papilionoidea: Lycaenidae: Poritiinae), Metamorphosis 32 (1), pp. 24-27 : 24-26

OBSERVATIONS

During seven visits to the TL in December and January 2020 –2021, approximately five mating events were observed. Mating occurred strictly in grass tussocks that surround the loose rocks and extensive rock slabs where the larvae feed on crustose Lichinaceae ( Coetzer, 2015; Van der Walt et al., 2020). Males persistently perched on grass stems at distances of between 5–15 cm down from the tips. Here they rhythmically opened and closed their wings, displaying the bright black and orange patterns on their upper sides.

On each visit, individuals were present at distinct spots in the small breeding area which, currently, spans approximately 650 m 2 ( Fig. 1 ). On arrival at the site, for instance, a first male or two were consistently found in the north-eastern extremity of the area, and females at the south-western extremity—the latter approximately 5 m away from the adjacent montane forest known as Forest Glens.

During one of the observed mating events, the female led the pair up the grass stem for a distance of approximately 10 cm upon disturbance, where they were partly screened by an unidentified maiden-hair fern ( Figs 2 A & B ). The male followed by working his legs in reverse. The mating session of this pair was measured as lasting for at least 1 hr 38 min. The angle at which the male abdomen connected with that of the female in this pair was found to be tilted, with the point of connection distanced from the female abdomen’s posterior end ( Figs 3 A & B ).

Closer examination of a different, captured female specimen showed that the ostium bursa, that is, the vaginal orifice or opening, was partially covered by a shiny, sclerotized, button-like structure (Fig. 4). This structure is situated at a distance away from the posterior abdominal tip, which corresponds with the field observation of the tilted angle of copulation, as described above. This button-like structure was also observed in other living females at the TL (Fig. 5).

A SEM micrograph of this structure brought additional aspects into focus ( Fig. 6 ). It is a cup that partially covers the vaginal orifice and opens into it. Inside this cup, external to or on top of the orifice, a folded substance is visible. Under a light microscope, where it was viewed prior to SEM, this substance appeared “waxy”. While preparing the specimen for SEM, Willie Landman made the same observation. The SEM micrograph shows that the substance is folded to create gaps that increase its volume.

Figures

Figure 1 – Google Earth polygon (shaded area) of TL breeding area of Alaena margaritacea; an area of about 650 m2.

Figure 2 – Mating pair, female on top and male below: A – female wafting her wings; B – pair moved to a position where they are screened by an unidentified fern.

Figure 3 – Mating pair, female on top and male below: A – red arrow indicates tip of female abdomen; B – images showing the titled angle of copulation: C – close-up of Fig. 3B.

Figure 6 – SEM micrograph of ostium bursa of A. margaritacea female. It is situated ventrally towards the posterior end of the abdomen. Note the hardened cup and the substance covering the orifice (image: W. Landman).