Phyllonorycter loxozona, Meyrick, 1936

Prins, Jurate De & Kawahara, Akito Y., 2012, Systematics, revisionary taxonomy, and biodiversity of Afrotropical Lithocolletinae (Lepidoptera: Gracillariidae), Zootaxa 3594 (1), pp. 1-283 : 115-116

The loxozona group

The forewing pattern in the loxozona group resembles very closely that of the majority of Afrotropical Phyllonorycter species. Larvae of the loxozona group feed on Dombeya spp. [ Malvaceae ]. Developed mines appear to resemble gall-like swellings.

The loxozona group consists of three species: P. didymopa ( Vári, 1961) , P. loxozona ( Meyrick, 1936) , and P. madagascariensis ( Viette, 1949) . Phyllonorycter madagascariensis was described from a single specimen without abdomen by Viette (1949). We made all possible efforts to find the holotype of P. madagascariensis (see Remarks below). A neotype designation is very much anticipated. We believe that with the kind help of the lepidopterists’ community it will be possible in the near future to obtain a neotype of this species reared from Dombeya spectabilis which grows in the Botanical Garden of Tsimbazaza, Antananarivo, Madagascar (type locality of P. madagascariensis ). Based on the original description, the forewing pattern of P. madagascariensis resembles that of P. didymopa . All three species make a long, semi-transparent gallery during the development of early instars and feed on Dombeya ssp. [ Malvaceae ] ( P. didymopa feeds on D. rotundifolia , P. loxozona on D. emarginata and D. rotundifolia , and P. madagascariensis feeds on D. spectabilis ). We, therefore, tentively included P. madagascariensis into this informal species group. Unfortunately, the unavailability of genitalia prevent a proper diagnosis between P. madagascariensis , P. loxozona and P. didymopa .

Male genitalia are known only for P. loxozona . They show a few, rather particular set of features characterizing this species: tegumen rather short, tuba analis long, protruding ca. 1/2 length of tegumen, long sinuate narrow valva covered with dense setation on cucullus (similar to Cameraria ), crescent-shaped vinculum with very short saccus, sternum VIII truncate, strongly tapering caudally with blunt weakly bidentate apex.

Female genitalia of the loxozona group, like those of Cameraria , are characterized by the location of ostium bursae opening at posterior margin of segment VII. Antrum in the loxozona group is broad and sclerotized, with strongly sclerotized ring encircling the opening of ostium bursae. Ductus bursae in the loxozona group like in Cameraria (the hexalobina and the landryi groups) might be crossed by a small plate situated anteriad antrum (in P. loxozona ). Corpus bursae of the loxozona group without signum.

Remarks. Vári (1961: 222) wrote the following: “It is an interesting peculiarity to find a gall-forming species in Lithocolletis , as most species make tentiform mines and no special growth of the leaf tissue is induced. A further interesting matter is the presence of the long, semi-transparent gallery, made during the early stages, whereas all other species are sapfeeding during this period, and no semi-transparent galleries are made”. This would indicate that the early instars of this group might possess a slightly different metamorphic development of mouthparts from the rest of Phyllonorycter . The male and female genitalia of the loxozona group resemble these of Cameraria . However such characters, as general pattern of forewing, absence of clearly notable setae on apex of tegumen, strongly developed complete transtilla, put these species close to Phyllonorycter . Probably, the loxozona group species might require a designation of a new genus. However, it seems preferable at the moment to follow a more conservative approach leaving this species group in Phyllonorycter , as initially proposed by Meyrick (1936: 33) until detailed larval and pupal morphology is studied and molecular characters are obtained.

Key to the species of loxozona group based on external characters and host plants

1. Second fascia at 1/2 of forewing slightly oblique towards apex, broader at dorsum and slightly tapering towards costa, blunt at costa ( Figs 81, 82, 85 ).................................................................................. 2

– Second fascia at 1/2 of forewing straight transverse, swelled at dorsal sector and bluntly tapering at costa; larvae feed on Dombeya emarginata and D. rotundifolia . [ Malvaceae ] ( Figs 83, 84 )....................................40. loxozona

2. Larvae feed on D. rotundifolia [ Malvaceae ]....................................................... 39. didymopa

– Larvae feed on D. spectabilis [ Malvaceae ]................................................. 41. madagascariensis

Key to females of loxozona group based on genitalia*

1. Anterior apophyses only slightly shorter than posterior apophyses; margin of ostium bursae not sclerotized (Fig. 331)................................................................................................. 39. didymopa

– Anterior apophyses more than 2× shorter than posterior apophyses; margin of ostium bursae heavily sclerotized ( Fig. 332 )..............................................................................................40. loxozona

* female genitalia of P. madagascariensis are unknown.

Figures

FIGURES 81–86. Adults. Scale bar 1 mm. 81, Phyllonorycter didymopa, holotype 6494♀, South Africa, Tswaing, 16.i.1955, in TMSA. 82, Phyllonorycter didymopa, ♀, South Africa, Tswaing, 16.xi.2004, leg. J. & W. De Prins, specimen ID: RMCA ENT 000003287. 83, Phyllonorycter loxozona, holotype ♀, Uganda, Busunju, 02.x.1935, leg. H.C. Taylor, in BMNH. 84, Phyllonorycter loxozona, ♀, South Africa, Rustenburg, 10–17.xi.1976, leg. Potgieter & Molekane, in TMSA. 85, Phyllonorycter madagascariensis, holotype, Antananarivo, leg. R. Paulian. The drawing is made by Willy De Prins after the original description and the drawing of Viette (1949: 175–176, fig. 5). 86, Phyllonorycter aarviki, holotype ♀, Tanzania, Morogoro, 25.iii.1992, leg. L. Aarvik, specimen ID: RMCA ENT 000004128.

FIGURES 332–333. Female genitalia. Scale bar 200 µm. 332, Phyllonorycter loxozona, holotype, the drawing is made by Willy De Prins after the genitalia prep. 6110, in BMNH. 333, Phyllonorycter aarviki, holotype, genitalia prep. MRAC/KMMA 00370, in RMCA.