Acanthopsyche Heylaerts, 1881

Usha, A. U., Sobczyk, T., Roby, T. J. & Jose, Joyce, 2022, Neotype designation, redescription, biology and distribution of Acanthopsyche alstoni Watt & Mann, 1903 (Lepidoptera: Psychidae) from India, Zootaxa 5159 (1), pp. 136-144 : 137-141

Acanthopsyche Heylaerts, 1881

Acanthopsyche Heylaerts, 1881 , Annales de la Société entomologique de Belgique, 25: 66 (key), 70.

Type species: Psyche opacella Herrich-Schäffer, 1846: 20 , by subsequent designation by Tutt (1900: 378).

Psychidae : Oiketicinae : Acanthopsychini ( Sauter & Hättenschwiler 1991: 84), Acanthopsyche alstoni Watt & Mann,1903

Acanthopsyche is characterized by males with bipectinated antenna and long ciliated pecten. Forewings with nine veins from dc and narrow scales. Hindwings with five veins from dc. Intercalary cell and accessory cell absent. Forelegs with long epiphysis, midleg and hindleg without spurs. Female apterous, eyes, antenna and legs rudimentary. Thoracic segments sclerotized dorsally ( Hampson 1892).

Acanthopsyche alstoni Watt & Mann, 1903: 197 , nr. 28, type specimens (unknown numbers of larval cases) lost ( Sobczyk 2011).

Type locality: India, “Duars”. The original description of A. alstoni Watt & Mann, 1903 is restricted to the larval cases.

Neotype examined: ♂. The Neotype is labelled as follows: 1) INDIA, Kerala, Athani, Ernakulum , (10.155517N and 76.354428 E) day of emergence, 13-11-2021, male 2) (supplementary specimen) Acanthopsyche alstoni , day of emergence 01-12-2021, female .

At present, the neotype are kept at the museum of the Department of Zoology , St. Thomas College , Thrissur as the work is a part of the doctoral degree of the first author. Once the thesis is submitted, the specimens will be transferred to Zoological Survey of India, India .

Material examined: INDIA, Kerala, Athani, Ernakulam (10.155517 N and 76.354428 E), altitude (15 mASL) 16 larval cases, Athani (Ernakulam);23 larval cases, Cheruthoni, Idukki;1 larval case, Anchuruli, Idukki;3 larval cases, Nariyampara, Idukki (all collected during 03-10-2021 to 05-01-2022. Usha) .

Supplementary description: ♂ ( Fig. 1a,b ): Relatively small species with brownish black and thick scaled wings. Body length 2.5–3 mm, Wingspan 7.4 mm, forewing length 3.2 mm, forewing width 1.6 mm, forewing index 0.5 mm.

Head. Covered densely with long brownish scales. Eyes medium-sized, black, interocular index 1.4 mm. Labial palpi fused. Tentorial pits and tentorium clearly pronounced. Antennae ( Fig. 2 ): 12 segments, antennae length 1.35mm, segments bipectinated, to apex uniformly decreasing, with cilia on the both sides. On the third and fourth antennal segment reaching maximum length, Scapus thickened, pedicellus disc-shaped.

Thorax. Forelegs covered with brownish hairs and tibia with epiphysis ( EPI: 0.64 mm). Distal tarsal segment slightly longer than other tarsal segments. Thorax measures 1.1 mm and with long brownish hairs. Abdomen is long 1.4 mm, covered with brown hair like scales. Wings over side thick scaled brownish black, without pattern, underside of both wings are with brownish scales ( Fig. 3a,b ).

Wing venation ( Fig. 4a,b,c ): Nine veins from dc forewing. In dc media stem undivided, dividing the cell into a larger anterior part and a small posterior part, without accessory cell. Sc runs parallel to the R veins to the apex. Median stem run in outer margin dc between M1 and M2. From dc edge R 3+ R 4 to one half stalked, with R 2 short stalked or from a point. The three M-veins are free. Two Cu veins are present and originate distally from dc. Basal fork of anal veins A1 and A2 are prominent. Hind wings with five veins from dc, this nearby M2+M3 distally expanded. Median stem undivided. Sc free ends in front of apex at anterior margin. R 1 at half its length with connecting bridge to dc. Three anal veins are free.

Abdomen. Genitalia ( Fig. 5 ): Elongated, 0.52 mm long, 0.28 mm with high fixed valvae. When closed, the valva do not protrude beyond the tegumen. Tegumen indented distally. Valva elongated tapering distally and present long hairs on the apex. Sacculus curved, distally covered with strong spines. Vinculum near the valva widest, evenly sclerotized, saccus distally very wide, slightly rounded. Phallus straight, shorter than genital length (0.31 mm), tapering distally. Presence of gnathos is not confirmed as they are invisible in the structure.

Larva. Larvae move actively on the hard objects like walls, gate, and concrete surfaces. The body of the larvae are light greyish colour and the head is highly sclerotized. The head capsule of the larvae is light yellowish with dark black patches on it. The length of a mature larvae is about 3–3.5 mm ( Fig. 6 ).

Pupal case (male). the pupal case of males is dark golden-brown colour and measures about 3 mm in length ( Fig. 7 ).

Larval cases. ( Fig. 8 a, b ) of this species are very small, sack like and conical in shape. Larval case is made up of small fragments of leaf and bark. Adult cases are almost cylindrical. The surface of the cases has a prickly appearance due to the presence of many minute spikes which are visible on close observation. Adult male cases measure 8.5–9.5 mm (2.1 mm width at centre). Cases of an adult female is slightly longer and wider than males ( Fig. 8b ); it measures about 11–12.5 mm (2.8 mm width at centre). Composition and structure of cases are similar in both sexes except size. The larval cases seemed to be attached directly to the leaf during pupation. At the same time on detaching the cases from the leaves, there were silken threads present. The thread becomes prominent during detachment or later in the course of weathering ( Fig. 8c ).

Female. ( Fig. 9a,b ): it is yellow, maggot shaped, with no wings and appendages. length 3.8mm. The head is clearly regressed, without any appendages. Sclerotization was observed on the head and thorax region and with dark brown in colour. Abdominal region is poorly sclerotized and packed with eggs.

DNA sequencing ( COX 1): The examined mitochondrial COXI (Cytochrome oxidase I) gene of A. alstoni is 653 bp long. The sequence has been uploaded to NCBI GenBank and Accession number is ON584252 . The nucleotide composition percentage of the species is 37.5( T), 17.3(C), 30(A), and 15.2(G).

Distribution and Range. Larval cases were collected from three districts (Wyanadu, Idukki and Ernakulam) of Kerala. The places and locations are plotted in Figure 10 . The altitude of the sites from where A. alstoni were collected ranges from 15 mASL to 1660 mASL. All sightings except Athani in Ernakulam (15 mASL) were above 700 mASL. The site at Athani was urban and predominantly a residential area with small homestead gardens around individual houses. All other sites were rural, in monoculture plantations near forest areas. The distance between the northern most observations to southernmost observation was 260km and east-west distance was 99 km. The diagonal area covered when joining all plots of observation was 12150 km 2 and its perimeter was 570.7 km. The diagonal area covered all types of land use and vegetation though all sites except Athani were situated near protected forest areas and near a wetland. Mean temperature range of the area was between 15°C and 35°C and rainfall was 350–450 cm.

Substrates and host plants. Larval cases and pupal cases were observed from Idukki and Ernakulam. Only pupal cases were observed from Wayanad. The larval cases were found moving actively on the hard surfaces such as walls, concrete slabs, building surfaces and also from live plants. The pupal cases were attached to different plant species. Significant damage to plants was not observed by this species. Maximum sightings of larval cases were from the surfaces of hard objects like walls, gates, etc in their larval stages. The pupae were attached mostly to the underside of leaves, twigs and bark. Nine species belong to eight families of plants are recorded as host plant of this species ( Table 1 ).

Life Cycle. The larval cases showed activity for a few days after collection and then become immobile. On examination the larvae were found to be dead. A. alstoni could not be successfully reared in the laboratory as the caterpillars died in the bag. Therefore, complete life cycle and many other characteristics of the species need further evaluation. Pupal cases from locations with cooler temperatures and high altitudes (Idukki and Wayanad) showed no emergence. Only cases collected from relatively higher temperature and lower altitude (Athani) showed emergence. Adults were obtained in the laboratory when they emerged from the pupal bags collected from the field. Therefore, the duration of various life cycle stages are indeterminate at present.

Discussion. Acanthopsyche Heylaerts, 1881 is one of the most widespread Psychidae genera ( Dierl, 1972). All previously known species have wingspans over 10 mm. The smallest known oriental species of the genus, Acanthopsyche minima Hampson,1900 is significantly larger with a wingspan of 12 mm. It was described from Sri Lanka (“ Ceylon, Puttalam”): “Uniform black-brown, wings rather sparsely clothed with black hairs, rather more thickly on basal half of inner area of forewing. Larval case covered with small land-shells, bits of the pupae of a large moth”. The genus Striglocyrbasia Sugimoto & Saigusa, 2001 includes similarly small species with a wingspan of less than 10 mm. This differs generically by a reduced number of veins (7–8 from dc fore wing, 3–4 from dc hind wing).

At the beginning of the investigations the specimen characters were compared to various species of psychids ( Sobczyk, 2011) and based on the observations it was placed in genus Acanthopsyche .

The characteristics of the specimen differed from other known species from the region. But the larval cases shape and size, attachment to the underside of the leaf and damage pattern in leaf (observed very rarely) matched with Watt & Mann (1903) original description: “ Acanthopsyche alstoni (?) n. sp. Found in Duars. 371. This the smallest species of all, found doing damage at Sylee, Duars, in November 1900. The larval cases are less than ¼ inch long, suspected by a thread. The insect acts on underside of the leaf and perforates it into a mass of minute perforations like shot. It has not been noticed elsewhere. We have not yet succeeded in obtaining the moth of this species.”

The identity of A. alstoni could only be determined because there is no agreement in the larval cases of other species. Neither in the plant protection literature ( Watt &Mann 1903) nor in taxonomic works ( Hampson 1900) is there information on other larval sacs of similar size and shape.

Figures

FIGURE 1a: ♂ Neotype of Acanthopsyche alstoni currently at STC Thrissur India—magnified view of head and thorax; b: ♂Neotype of Acanthopsyche alstoni at STC Thrissur India—full body view.

FIGURE 2: ♂ Antenna (detached)

FIGURE 4a: ♂ Fore Wing venation, descaled, coloured in Fuchsine, mounted in alcohol; b: ♂ Hindwing Wing, descaled, coloured in Fuchsine, mounted in alcohol; 4c: Wing venation.

FIGURE 5: Genitalia (male) dorsal view, mounted in Canada Balsam.

FIGURE 6: Larval case and dorsal view of larva of Acanthopsyche alstoni.

FIGURE 7: Lateral view of pupal case (male)

FIGURE 8a: Male and female cases; b: Male case, pupal case and adult; c: Male bags and pupal cases.

FIGURE 9a: Female case, pupal case and adult; b: Female adult.

FIGURE 10: Distribution map of Acanthopsyche alstoni

FIGURE3a: ♂ Forewing; b: ♂ Hind wing.