Three new species of Oxyethira Eaton, 1873 (Trichoptera: Hydroptilidae) from New Caledonia

Oxyethira Eaton, 1873 is one of the most diverse genera of Hydroptilidae, comprising over 240 species distributed in all biogeographical regions. Here three new species of Oxyethira (Trichoglene) Neboiss, 1977 are described and illustrated from male specimens collected in New Caledonia: O. (Trichoglene) hamus sp. nov., recognized by the hook-shaped apex of the long inferior appendages in lateral view and by the posterior margin of segment IX with a trilobed appearance in ventral view; O. (Trichoglene) rectangulata sp. nov., recognized by the rectangular shape of the inferior appendages, which are totally fused and with two pairs of small setae on the inner face; and O. (Trichoglene) spiralis sp. nov., recognized by the strongly curvilinear shape of the subgenital process in dorsal and lateral views and by the long process spiralling around the ejaculatory duct at the phallus apex.

The diagnostic characteristics for the males in the subgenus Trichoglene are as follows: segment VIII without excision (considered as a plesiomorphic feature); short titillator (even absent in some species); phallus with a curved spine-shaped process in the sub-distal region; and subgenital processes widely separated and partially fused with the pleural region of segment IX (the two latter are considered apomorphic features) (Kelley 1984).
Three species groups are recognized among the New Caledonian members of the subgenus Trichoglene: the spinifera-group, with abdominal segment IX subquadrate; the caledoniensis-group, with venter of abdominal segment IX in ventral view produced anteriorly, proximally either rounded or tapered and somewhat triangular; and the insularis-group, with Y-shaped inferior appendages (Wells & Johanson 2015).
In this study, three new Oxyethira (Trichoglene) species are described, two belonging to the caledoniensis-group (O. spiralis sp. nov. and O. hamus sp. nov.) and one belonging to the spiniferagroup (O. rectangulata sp. nov.).

Material and methods
The material was collected using Malaise traps (Gressit & Gressit 1952) and preserved in 80% ethanol. For examination of the male genital structures, the abdomen was removed and cleared in 10% KOH and mounted temporarily in glycerin or glycerin jelly on a slide for viewing and drawing. Pencil sketches were made using a drawing tube mounted on a Leitz Laborlux S light microscope, and then scanned and used as templates to produce vector graphics in Adobe Illustrator ver. CS6. The removed abdomens were then stored permanently with the rest of their respective bodies in microvials with 80% ethanol. The terminology used in the descriptions follows that of Kelley (1984).
Male genitalia (Fig. 1A-D). Abdominal segment VIII almost cylindrical, with shallow incision at posterior margin in ventral view (Fig. 1C). Abdominal segment IX inserted within segment VIII; anterior margin forming three lobes in ventral view (Fig. 1C), surpassing anterior margin of segment VIII (Fig. 1A-B). Segment X not visible. Subgenital processes slightly curvilinear in dorsal view (Fig. 1B), each with pointed apex curved downward in lateral view and one bilobed process at base (Fig. 1A). Inferior appendages fused, with strongly sclerotized margins, bearing one pair of small mesal setae at posterior margin visible in dorsal (Fig. 1B) and ventral views (Fig. 1C), and one pair of small setae at inner margin visible in dorsal view (Fig. 1B); posterior margin slightly concave; in lateral view hook-shaped with apex curved backward and touching base of subgenital process (Fig. 1A). Setal lobes absent. Aedeagus elongate; in subdistal region, slender spine pointing left in dorsal view. Titillator absent (Fig. 1D). Paratypes 2 ♂♂; same collection data as for holotype; NHRS.
Male genitalia ( Fig. 2A-D). Abdominal segment VIII cylindrical with wide, V-shaped incision in ventral view (Fig. 2C). Abdominal segment IX inserted within segment VIII; anterior margin slightly concave, not surpassing anterior margin of segment VIII (Fig. 2B-C). Segment X not visible. Subgenital processes almost straight in dorsal (Fig. 2B) and ventral views (Fig. 2C), each bearing one bilobed process at base. Inferior appendages fused, rectangular in dorsal (Fig. 2B) and ventral views (Fig. 2C), bearing two pairs of small mesal setae at inner margin visible in dorsal view (Fig. 2B); divided into two parts in lateral view ( Fig. 2A): dorsal part forming a truncate hump, ventral part forming pointed projection. Setal lobes absent. Aedeagus elongate, with slender apical spine curved left in dorsal view. Ejaculatory duct extending freely at apex. Titillator absent (Fig. 2D).

Diagnosis
Based on general similarities, Oxyethira (Trichoglene) spiralis sp. nov. is tentatively placed in the group of Oxyethira caledoniensis. It is similar to O. caledoniensis Kelley, 1989 by the shape of segment IX in ventral and lateral views, with the anterior margin only slightly produced anteriorly and by the shape of the apparently fused inferior appendages. In O. caledoniensis the inferior appendages are widely separated and form bilobed sclerotized structures that are absent in O. spiralis sp. nov. The new species can be recognized in lateral view by the subquadrate shape of the inferior appendages, by the strongly curvilinear shape of the subgenital process in dorsal and lateral views, and by the long process spiralling around the ejaculatory duct at the phallus apex.
Etymology ʻSpiralisʼ, from Latin, ʻspiralʼ, referring to the shape of the long process present around the ejaculatory duct in this species.

Discussion
Despite the great morphological variation present in the genitalia of Oxyethira, all species described here present characteristics unique for the subgenus Trichoglene (Kelley 1984): segment VIII without modification; and widely separated subgenital processes that are partially fused with the pleural region of segment IX.
There are different distribution patterns for Oxyethira species in New Caledonia ranging from wide to localised, or even disjunct (north-south extremes) (Wells & Johanson 2015 Wells & Johanson, 2015. These species can be well localized or widely distributed in the Sud Province but are never found in the northern region (Province Nord) (Wells & Johanson 2015). Oxyethira (Trichoglene) spiralis sp. nov is only known from its type locality in the Province Nord. Wells & Johanson (2015) reviewed the New Caledanian Oxyethira species and described 17 new species, bringing the total number of species for the island to 26. Of these, 11 species belong to Trichoglene. Together with the herein described species the diversity of Oxyethira on New Caledonia is increased by about 10%, and of those in Trichoglene by almost 30%.
The three new species were found among several thousand New Caledonian Hydroptilidae stored in ethanol and collected at the end of 2003 and beginning of 2004. This means that new species can still be found in material from well-studied areas that have given rise to descriptions of dozens of new species in the family Hydroptilidae (Wells & Johanson 2012, 2014, 2015Wells, Johanson & Mary-Sasal 2013). This shows the potential for finding new Hydroptilidae in New Caledonia and that undescribed species are still available in collections or likely not yet collected.