Perrotia albiplaga Oberthür, 1916

Cock, Matthew J. W. & Congdon, T. Colin E., 2014, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera). Part 7. Hesperiinae incertae sedis: grass and bamboo feeders, Zootaxa 3872 (4), pp. 301-354 : 323-327

Perrotia albiplaga Oberthür, 1916

This Madagascan endemic is extremely rare in collections. Oberthür (1916) described and illustrated it from a male collected by the Perrot brothers at Fénérive (lowland forest) in the first quarter of 1896; Evans (1937) reports only the type in the BMNH. In the same paper, Oberthür described and figured P. albimacula , also captured by the Perrot brothers at ‘Antakares (Isokitra à Diego Suàrez)’. Evans (1937) treats P. albimacula as a subspecies of P. albiplaga , suggesting it may prove to be just a variety, and lists only the male type in the BMNH; however, the wing pattern of this specimen is significantly different from the holotype of P. albiplaga . A third species, P.

teresina (Oberthür) was described from a female captured at ‘Forêt du Rogez entre Tananarive et la Côte orientale de l'ile’ (i.e. Andekaleka (lowland forest), D.C. Lees pers. comm. 2012) by C. Lamberton; Evans treats this as a synonym of P. albiplaga albimacula , and lists only the female type in the BMNH. Viette (1956) indicates that subspecies are not justified and so P. albiplaga is monotypic, but adds no new localities. Ackery et al. (1995) and Lees et al. (2003) follow this treatment, although D.C. Lees (pers. comm. 2012) and T.B. Larsen (pers. comm. 2012) indicate that P. albimacula may prove to be a valid species, and P. t e res i na is likely to be a synonym of P. albiplaga . D.C. Lees (pers. comm.) advises that he is aware of only one further specimen, collected at Ambinanindrano by R.K. Kestell-Cornish around 1917, making at most four known specimens at this time.

Given this apparent rarity, it is somewhat astonishing that during a visit to Madagascar, MJWC found three caterpillars of this species (90/208) at Andasibé (Perinet), less than a mile from Lac Vert (to the west of Lac Vert, Perinet, position estimated at 18.942°S, 48.427°E). One female ( Figure 22 ) was reared. Only in 2012 was this specimen correctly identified by D.C. Lees and T.B. Larsen in the early stages of preparing this paper. It resembles the female type of teresina, but the UPF spots are reduced. Unfortunately little detail of the early stages was recorded at the time of collection, and the following is based mostly on the photographic record made and preserved penultimate instar caterpillars.

Food plant

The food plant on which caterpillars were found was a large bamboo. It was identified recently by Dr. S. Dransfield (Royal Botanic Gardens Kew) from Figure 23 as probably Decaryochloa diadelpha , a Madagascan endemic and the only species of its genus, which is very common at Andasibé.

Leaf shelters

A leaf shelter is shown in Figure 23 ; the shelter is made with a basal cut, and the distal half of the leaf is folded upwards to the apex; feeding is from the basal end of the shelter, leaving the margin intact and free, and basal to the shelter from the leaf edge on the opposite side of the leaf. Figure 25.1 shows the final instar caterpillar in a leaf shelter made by rolling a whole leaf upwards, but whether the open shelter reflects what was found in nature, a shelter under construction, or an artefact of remaking the shelter in captivity, cannot now be determined.

Caterpillar

One n-2 instar caterpillar was found about to moult to the penultimate instar ( Figure 24 ); Head 2.0 x 2.3mm wide x high; widest just below middle, indent at vertex; black with a diffuse pale patch on each epicranium from below apex parallel to epicranial suture, a sharply defined pale arc from base of adfrontals, running posteriorly basal to stemmata, and a sharply defined pale rhomboid patch above stemmata, just touching the arc. Pronotum black; black anal shield apart from the margin, where there are visible pale setae; the body is dull translucent pale green, the dorsal line darker; the body segments are ridged or folded in the posterior half; only spiracles T1 and A8 are visible and they are orange-brown.

The head of the penultimate instar caterpillar ( Figure 25 ) is wider nearer base, indent at vertex; 2.6 x 2.9mm wide x high (n=2); ground colour pale brown; a striking conspicuous black marking from vertex down face, widening from the vertex to about the top of the frons, then narrowing abruptly in the basal half of the frons, before widening as far as the inner stemmata just above the mouthparts; a broad pale yellow-white band outside this, the outer margin more or less straight from vertex to inner stemmata, extending posteriorly over the stemmata; a short dark line through the anterior stemmata; the posterior margin of head slightly darkened. Pronotum narrowly black on posterior margin; body dull translucent pale green, the dorsal line hardly differentiated; segments ridged or folded in posterior half; spiracles T1 and A8 conspicuous orange-brown, other spiracles orange-brown, but much less conspicuous; gonads on A5 yellow and sharply defined.

The final instar caterpillar ( Figure 26 ) is similar to the penultimate instar: head 3.0 x 4.0mm wide x high; head ground colour is a darker brown; the central black marking on the face is relatively narrower, except just above the mouthparts where it is comparable; the pale yellow-white band outside this is relatively narrower and the lateral margin concave. The head and body have scattered very short, pale, erect setae, longest around mouthparts and around margin of anal plate.

Pupa

The pupa ( Figure 27 ) was formed in the final leaf shelter, which is silk lined; a sparse sprinkling of white waxy powder on lining of shelter and on pupa, strongest around thorax; the cremaster is attached to the silk lining; there does not seem to have been a silk girdle. The pupa measured 23mm; proboscis sheath extends to cremaster; no frontal spike; ground colour dark brown; wings, legs and much of ventral abdomen light brown; short brown erect setae on head, dorsal thorax and abdomen; spiracles a contrasting light reddish orange-brown; true legs pale brown. Pupation lasted 18 days.

Figures

FIGURE 22. Pinned female Perrotia albiplaga, collected 16 Aug 1990 as final instar caterpillar on? Decaryochloa diadelpha, Andasibé, Madagascar; adult 15 Sep; 90 / 208 A. Scale bar 10 mm.

FIGURE 23. Leaf shelter of Perrotia albiplaga on? Decaryochloa diadelpha, Andasibé, Madagascar, 16 Aug 1990; 90 / 208. The food plant identification was made from this photo.

FIGURE 24. Instar 3 premoult caterpillar of Perrotia albiplaga collected and photographed 16 Aug 1990 on? Decaryochloa diadelpha, Andasibé, Madagascar; preserved; 90 / 208.

FIGURE 25. Instar 4 caterpillar of Perrotia albiplaga collected and photographed 16 Aug 1990 on? Decaryochloa diadelpha, Andasibé, Madagascar; preserved; 90 / 208. Note the shelter was full of water from a recent shower when collected.

FIGURE 26. Instar 5 caterpillar of Perrotia albiplaga collected and photographed 16 Aug 1990 on? Decaryochloa diadelpha, Andasibé, Madagascar; pupated 28 Aug; 90 / 208 A.

FIGURE 27. Pupa of Perrotia albiplaga collected as final instar caterpillar 16 Aug 1990 on? Decaryochloa diadelpha, Andasibé, Madagascar; pupated 28 Aug; photographed 31 Aug; adult 15 Sep; 90 / 208 A.