Metura oceanica Viette, P. E. L. Viette 1963
Creators: name: Beaver, Ethan P.
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Lepidoptera
Psychidae
Metura
Metura oceanica

description: Metura oceanica Viette, 1963
(Figs 2 E–F, 4E–F, 4L, 6E, 7B, 7E–F)
Metura oceanica Viette, 1963: pp. 142. Nielsen et al. 1996: pp. 35.
= Metura occanica Viette, 1963 (original misspelling).
Holotype: ♂, ‘Noumea, N. Caledonie, 29-VIII-55, J. Rageau / P.E.L. Viette det 1957, Metura oceanica m.s. male, holotype, P. Viette / 3115 / TYPE / Museum Paris 1957 coll P. Viette / Metura sp. n. near elongata Saunders det D.S. Fletcher 1955’ in MNHN (examined by photograph, Fig. 2F).
Paratype: 1 ♂ ‘New Hebrides [Vanuatu], Malekula, Ounua, Mar-April 1929, L.E. Cheesman, BM 1929-343 / 51. / Metura oceanica Viette, P.E.L. Viette det’ in NHM (examined by photograph, Fig. 2E).
Type locality: Noumea, New Caledonia.
Additional material examined: 2 ♂ larval bags (in WRI): Duck Island, New Caledonia, 19 November 2004, J. T. Jennings.
Diagnosis. Adult male M. oceanica are immediately distinguished from all other Metura species by the scale pattern at the dorso-anterior aspect of the abdomen, which in M. oceanica is black with an orange triangle (Fig.
2E). The species is otherwise similar to M. aristocosma and M. phyllosacca, except that the hindwing termen in this species is straight, however it is convex medially in the other two species. There genitalia are distinct from M. phyllosacca and are covered under that species. The mature larva is similar to M. elongatus except in M. oceanica the pronotal shield has the anterior and posterior edges black, and the orange colouration of the head is broken into three sub-triangular markings, separated by black, while in M. elongatus the head is entirely orange. The mature larval bag is comprised largely of foliage and in this way is similar only to M. phyllosacca. Unlike M. phyllosacca, the larval bag also has large areas of bare silk, and tends to have the largest leaves placed close to the anterior aperture, whereas in M. phyllosacca the largest examples of foliage adornment are situated approximately in the middle, and are less ‘top heavy’ in appearance. The posterior aperture is often bare of foliage in male M. oceanica specimens while in M. phyllosacca it is heavily adorned with small fragments of foliage, however this is subject to variation in some M. oceanica examples.
Redescription. Male. (Fig. 2 E–F) Forewing length 17-19 mm, hindwing 10 mm, expanse 40 mm (holotype). Head. Antennae bipectinate, black. Frons dark grey, ventral area black.
Thorax. Patagium and tegula yellow-ochreous, mesoscutum and mesoscutellum black dorsally, mesoscutum with some yellow-ochreous scales anteriorly in some specimens. Prothoracic legs yellow-ochreous, meso- and metathoracic legs the same but tinged with black dorsally. Forewing elongate, triangular; costa concave medially, gently convex toward blunt apex, termen subtly convex medially, inner margin concave posteriorly, convex anteriorly. Hindwing costa highly convex, apex blunt, termen mostly straight, inner margin expanded, convex. Both forewing and hindwing surface black, distal ends of all veins lightly scaled, transparent. Underside similar.
Abdomen. Black, dorsal anterior with conspicuous yellow-ochreous triangular marking tinged with grey scales. Intersclerite membrane unscaled, light brown. Ventral yellow-ochreous.
Sternite SVIII (Fig. 4L) anterior apophyses long, outer lateral margins convex, anterior margin concave, paired lateral ridges to near middle. Posterior margin weakly concave, lateral margins weakly concave.
Genitalia. (Fig. 4 E–F). Saccus narrow, elongate, posterior margin long, narrow ‘V’ shape. Vinculum with vincular arms straight, not parallel on inner margin with saccus, outer margin membranous towards tegumen. Tegumen outer margin straight. Uncus broad, higher than wide, triangular, posterior apex pointed, bifurcate, setose on dorsal aspect, lateral margins mostly straight. Transitellar arms anterior margin weakly convex, posterior weakly concave. Valvae broad, apexes bifurcate to two lobes, ventral lobe shorter, rounded, short spines at apex, inner surface with many short spines, sacculus pronounced, rounded, lightly spined at apex, otherwise smooth. Phallus elongate, ventrally concave, dorsally convex, ductus ejaculatorius heavily spined, vesica moderate, straight, smooth, dorsal aspect angular.
Female. Unknown.
Larva. Figure 7F. Head with dark ochreous colouration broken into three sub-triangular markings separated by black dorsally. Pronotal shield of thorax dark ochreous with anterior and posterior margins black, with two black parallel lines along lateral surface. Medial line white. Meso- and metathorax similarly patterned. Thoracic legs black, heavily sclerotised.
Larval Bag. (Figs. 6E, 7B, 7E) 60-100 mm length, 20 mm width. Silk grey to whitish cream. Adorned with foliage of the larval food plant, primarily leaf fragments 3-15 mm long. Largest foliage fragments typically attached at anterior aperture and at widest point of bag. Posterior aperture bares of foliage.
Distribution. (Fig. 9A). Endemic to New Caledonia:Amédée Islet; Duck Island; Hienghène village; Île des Pins; Lifou Island; Mare; Noumea; Paagoumène; Pouembout; Tiendanite; Tina sur mer; Voh; and Vanuatu: Malekula.
Biology and phenology. This species is found most commonly on the western Pacific native Acacia simplex (Sparrm.) Pedley (Mimosoideae), Ixora margaretae (N.Hallé) Mouly & B.Bremer (Rubiaceae), Casuarina equisetifolia L. (Casuarinaceae), Myoporum crassifolium G.Forst. (Scrophulariaceae) as well as on introduced potted Melaleuca (Myrtaceae) (T. Salesne pers. comm), and has also been regarded as a pest of other garden plants and ornamental street trees in urban areas such as on Terminalia catappa L. (Combretaceae), Psidium guajava L., Eugenia brasiliensis Lam. (Myrtaceae) and Delonix regia (Boj. ex Hook.) Raf. (Fabaceae) (Viette 1963). In some years, hundreds of specimens can be observed from individual trees (T. Salesne pers. comm) however this is subject to some sporadic temporal variation. The species is common coastally along littoral vegetation behind beachfronts, dry forest, and in urban and agricultural areas, and is a pioneer species after habitat disturbance or succession. The type specimens are from March-April, and a further specimen from June, reflective of a typical wet season flight period. Considerable variation exists in size, number, and location of foliage adornment on the larval bag, some specimens are heavily adorned with foliage (Fig. 6E, 7 B–E) while, less commonly, others are almost bare (Fig. 7F), which may depend on available foliage for larval bag construction, or weathering. The larva in Figure 7F utilises the extremely narrow foliage of Casuarina equisetifolia which may account for the bare design.
Remarks. Metura oceanica is listed as an Australian species by Nielsen et al. (1996) however this is in erratum, as the species is known only from New Caledonia and surrounding islands (Viette 1963). The origin of this listing is unknown however could be attributed to misidentification of the then known but undescribed M. phyllosacca which is superficially similar. Despite the apparent abundance of M. oceanica in New Caledonia, no specimens were available for dissection. Aspects of the species description along with the genitalia diagram (Fig. 4 E–F, 4L) provided herein are based also on that presented by Viette (1963), who was thorough in his original description, as only photographed specimens were available for comparison. A dorsal image is provided of the paratype (Fig 2E) rather than the holotype, as the orange scales at the anterior dorsal aspect of the abdomen are in better condition in this specimen.
description: Published as part of Beaver, Ethan P., 2020, Revision of the genus Metura (Lepidoptera: Psychidae) with description of two new species, pp. 188-210 in Zootaxa 4861 (2) on pages 205-208, DOI: 10.11646/zootaxa.4861.2.2, http://zenodo.org/record/4414734