Holocacista Walsingham & Durrant
van Nieukerken, Erik J. & Geertsema, Henk, 2015, A new leafminer on grapevine and Rhoicissus (Vitaceae) in South Africa within an expanded generic concept of Holocacista (Insecta, Lepidoptera, Heliozelidae), ZooKeys 507, pp. 41-97: 47-51
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|Holocacista Walsingham & Durrant|
Taxon classification Animalia Lepidoptera Heliozelidae
Holocacista ; Nielsen (1980): 105 [re-description in unpublished thesis].
Very small moths, wingspan between 3 and 5 mm, usually with a pattern of metallic-silvery spots, but in some species not metallic, typically comprising a dorsal and costal spot at 1/4 sometimes united into a fascia and a postmedial fascia, which also may be broken into two spots. In some species part of this pattern is absent. Males never with androconial scales or hair-pencils. Separated from externally somewhat similar Antispila species by the reduced venation (Figs 29-34); in Antispila the discoidal cell is present and more veins are retained (Fig. 35); also most Antispila species are larger and have more antennal segments. Separated from most Heliozela species by more extensive colour pattern, the few Heliozela that do have more spots can be separated also by the venation with discoidal cell (Fig. 36), also Heliozela species have more antennal segments. Species of Antispilina and some in the " Antispila " ampelopsifoliella group have a very similar venation and are more difficult to separate; most Holocacista differ in the male genitalia by the usually long appendix on the phallus, moreover they have a small epiphysis, which is absent in the other genera with reduced venation.
Adults. Very small moths, forewing length ca. 1.5-2.5 mm (wingspan ca. 3-5 mm).
Head (Figs 21-24). Almost oval in outline. Eyes in latero-ventral position, ventral margin not reaching lower margin of head. Eye phragma narrow, weakly melanised. No sutures present. Anterior tentorial arms very slender, prominently curved laterally before converging towards frons. Vestiture comprising lamellar scales, firmly appressed on head, in dry specimens scales on vertex sometimes raised, probably an artefact as a result of drying. Mouthparts: labrum narrow, pilifers absent. Mandibles small, as long as broad, relatively well sclerotised (Fig. 23). Maxilla with galea well developed and longer than head; maxillary palp reduced to a single segment. Labial palp well developed, 3-segmented, drooping, slightly shorter than head capsule; distal segment from slightly longer to 1.5 × second segment; depression for Organ von Rath not seen. Antenna (Fig. 24) ca. half length of forewing with 14-20 segments [best counted in denuded specimens on slides], no sexual dimorphism. Scape and pedicel of equal length, slightly shorter than flagellomeres. Flagellomeres cylindrical, longer than wide, each with two annuli of scales, often differently coloured, resulting in visible dark and pale rings from above. Pecten present, but not easily visible; Nielsen (1980) counted 4-6 hairs in Holocacista rivillei .
Thorax. Vestiture of appressed lamellar scales, usually concolorous with ground colour of forewings. Foreleg with small but distinct epiphysis of about 36-48 μm in Holocacista rivillei (Fig. 26) to 50-82 µm in Holocacista capensis (Fig. 25), distinctly smaller than in Heliozela (Fig. 27) (150-165 μm in two measured European specimens) and without the microtrichia along the inner side, which probably serve as antennal cleaning apparatus. In Antispila , Antispilina (Fig. 28) and Coptodisca epiphysis completely lacking.
Wings. Male retinaculum a series of 7-12 hook-shaped bristles, arising from a thickened serrate portion of Sc. Frenulum in male a strong curved bristle (e.g., Fig. 30), in female two bristles present (Figs 29, 34); no pseudofrenular bristles in male. Humeral field with scattered microtrichia, otherwise restricted on wing membrane to area just posterior of retinaculum, arranged in longitudinal rows. Scale sockets regularly spaced, not in distinct rows.
Venation in forewing (Figs 29-34) with Sc to middle of costa. R unbranched, a separate vein, to costa. Rs with M and CuA, ending in 3-4 branches, interpreted as Rs1+2 to costa, Rs3+4 to termen, M and CuA to dorsum; in one species, Holocacista sp. _Terminalia_SA, tentatively placed here, Rs+M+Cu even more reduced, with only 2 branches. Hindwing with Sc+R to costa, Rs+ M with 2-3 branches, Rs to costa, 1 or 2 branches of M to termen and dorsum; CuA a separate vein to dorsum.
Wing pattern (Figs 1-16). On forewing typically comprising a pair of opposite pale, often metallic spots at 1/3 and a similarly coloured fascia or opposite spots at 2/3 on a dark background, brown to black, or brassy and shining. Variation exists in relative size, whether spots are joined to a fascia, or fascia is broken, or spots may be absent (e.g., Figs 11, 14, 16). Many species show sexual dimorphy in pattern, with females having more or larger pale elements than male. Only a single species from Arabian Peninsula has a different pattern with much yellow, probably as an adaptation to the desert habitat (Fig. 13). A fringe line often available, with fringe scales pale. Hindwings uniform grey. Androconial scales absent in all species examined.
Pregenital abdomen. Abdominal sclerites weakly sclerotised. Anterior sternum II subtriangular, free.
Male genitalia. Vinculum (S IX) very long, anteriorly often reaching beyond anterior margin of segment VI, almost cylindrical; tegumen (TIX) narrow, usually with a medial posterior process, probably a composite structure with uncus. Gnathos absent. Valva rather narrow, with stalked pectinifer halfway to inner margin, pecten comprising 6-12 blunt sensilla; transtilla typically with medial anterior projection, sublateral processes long. Phallocrypt (manica) with some to many strongly-sclerotised conical spines, often arranged in an asymmetric fashion, or with many smaller spines. Phallus outer tube often with remarkable ventrally-curved appendix on phallus, or appendices of different sizes and shapes. Juxta present and often bilobed or reduced to narrow ventral process.
Female genitalia. SVIII pointed, T VIII deeply indented. Oviscapt with few lateral cusps. Anterior and posterior apophyses subequal in length. Spermathecal papilla usually with circular sclerotisation. Ductus spermathecae with many coils.
Larva. Larvae yellow or whitish, usually with darker head capsule. Larva of Holocacista rivillei described in detail by Grandi (1931) and Marchi (1956). Head prognathous, legs and prolegs absent, but paired ambulatory calli on T2 and 3 (ventral and dorsal) and fused ventro-medial - calli on A3-6. Larvae with four feeding instars and a fifth non-feeding instar that constructs the case in which it pupates.
Hostplants. Several species feed on Vitaceae and Rubiaceae , a few species on Anacardiaceae , and single species each on Balsaminaceae , Dilleniaceae , Geraniaceae and Plumbaginaceae . A species feeding on Combretaceae is tentatively added, but this requires confirmation.
Life history. Eggs are inserted in leaf tissue, often near a vein or leaf margin. All species construct leafmines (Figs 70-75, 79, 83-93), usually starting as a narrow linear mine, later usually widening into a blotch, or sometimes remaining an irregularly wide gallery, and cut out an oval shield, comprising the epidermal layers, during the penultimate instar. Frass is deposited in a central line in the mine or filling the mine, later often scattered in the blotch or pushed by the larva to one side. The shields (Figs 76-78), later forming the cocoons, are more or less flat, without the raised ridge that is characteristic for Antispila . They attach this cocoon to any surface (trunks, leaves, leaf litter, etc.) where the non-feeding final instar larva pupates. Adults are usually day flying (Figs 80-82), and rarely come to light.
Mainly Old World tropics and subtropics: Afrotropical, Oriental and Australian regions, north to Taiwan and southern Europe (type species). Some DNA barcodes suggest that the genus also occurs in South and Central America, but no adults have yet been studied from this area.
The species listed in the checklist below, both named ones and unnamed ones, share the external and venation characters described above, and those dissected also the male genitalia characters. Those species that we have been able to sequence form a well-supported clade in a phylogenetic analysis (both Bayesian and Maximum Likelihood) of the Heliozelidae based on four genes (unpublished study in progress), as part of a larger clade of genera with reduced venation (including also Antispilina Hering, 1941, Coptodisca Walsingham, 1895 and the " Antispila " ampelopsifoliella group). While checking several Indian species described by Meyrick, we could also change the following generic assignment: Heliozela anna (Fletcher, 1920), comb. n. (from Antispila , feeding on Myrtaceae ) (Figs 20, 36), whereas the following remain in their original genus: Antispila argostoma Meyrick, 1916 (Figs 18, 35) and Antispila aristarcha Meyrick, 1916 (Fig. 19), both feeding on Vitaceae . While we assign an unnamed species feeding on Impatiens from Vietnam to Holocacista here (Figs 16, 34), the Indonesian Microplitica metadesmia (Meyrick, 1934) that likewise feeds on Impatiens , has a completely different venation, more similar to Heliozela Herrich-Schäffer, 1853. Pending further study of this species and the type species of Microplitica Meyrick, 1935 ( Microplitis desmophanes Meyrick, 1922), we leave it in Microplitica for now.
In the checklist below we provide the original genus in brackets, type locality, and the hostplant of the types. The species are listed geographically, first the named ones, then the unnamed ones.
Malta, Vitis vinifera L. [type species]
Holocacista capensis van Nieukerken & Geertsema, sp. n.
South Africa, Western Cape, Paarl, Vitis vinifera L.
South Africa, [Kwazulu Natal], Durban, [ Rhoicissus sp.]
South Africa, Western Cape, Cape Town, Pelargonium cucullatum (L.) L’Hérit.
African species [see also Appendix A]
sp. Terminalia_SA [placement tentative]
South Africa, Terminalia prunioides M.A. Lawson ( Combretaceae )
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