Leucotrichia Mosely, 1934

Thomson, Robin E. & Holzenthal, Ralph W., 2015, A revision of the Neotropical caddisfly genus Leucotrichia Mosely, 1934 (Hydroptilidae, Leucotrichiinae), ZooKeys 499, pp. 1-100 : 6-7

Taxon classification Animalia Trichoptera Hydroptilidae

Genus Leucotrichia Mosely, 1934

Leucotrichia Mosely, 1934: 157 [Type species: Leucotrichia melleopicta Mosely, 1934, original designation]. Flint 1970: 3 [key, revision]. - Marshall 1979: 178 [review of the genus]. - Oláh and Johanson 2011: 152 [discussion of Leucotrichia genus cluster].

Description.

Male. Length of forewing ca. 2.0-5.0 mm. Wings unmodified, lacking a pouch, bulla, or patches of scales; forewing broad basally, acute apically; hind wing narrow, more acute than forewing, with row of hooked setae basal to cross vein r (Fig. 1E), edges with long setal fringe. Head with 2 or 3 ocelli; bearing setae and pair of setiferous posterolateral warts, dorsal region sometimes bearing modifications such as eversible posterolateral warts, patches of scales in place of setae, or setiferous protuberances (Figs 1A, 3, 4); antennae generally simple and unmodified, all flagellomeres of uniform size and shape, except in some species in which they may be elongate or have an inflated appearance (Figs 1A, 3). Maxillary palps with 5 segments, labial palps with 3 segments (Fig. 1B). Tibial spur count 1, 3, 4 (Fig. 1D). Mesoscutellum with transverse suture; metascutellum pentagonal (Fig. 1C). Genitalia. Abdominal sternum VII with single mesoventral process or tuft of prominent setae (Figs 2B, D, 34B). Sternum VIII produced posteroventrally beneath segment IX (Fig. 2B), with a posteromesal division (Fig. 2D). Segment IX open ventrally, sternum not developed (Fig. 2D), posterolateral margin with row of prominent setae (Fig. 2A). Tergum × with heavily sclerotized lateral plates, consisting of ventral and dorsal sclerites, and membranous apex (Fig. 2A). Subgenital plate connected dorsally to ventral angles of tergum × sclerites, produced ventrally as elongate mesal sclerite extending to base of inferior appendage, sometimes with dorsal arm (Fig. 10A), always with ventral arm (Fig. 2A, 10A). Inferior appendage simple, elongate, sometimes fused mesoventrally, generally with dorsal spine (Fig. 2A, D). Phallus tubular basally, constricted at midlength with median complex bearing basal loop and pair of spherical “windows” (Fig. 8E, F), basal loop sometimes extended on pair of basal supports (Fig. 10F); apex large, membranous, sac-like, generally bearing spines or sclerites.

Species relationships.

The species of Leucotrichia are divided into 2 main species groups based on adult features, as originally defined by Flint (1970). The pictipes species group is considerably smaller in species diversity than the melleopicta species group consisting of only Leucotrichia fairchildi Flint, 1970, Leucotrichia imitator Flint, 1970, Leucotrichia pictipes (Banks, 1911), and Leucotrichia sarita Ross, 1944 (Table 1).

Character states that distinguish members of the Leucotrichia melleopicta species group include males bearing 3 ocelli, a mesoventral process on sternum VII, an unmodified head (except for Leucotrichia chiriquiensis Flint, 1970), and 1 or 2 large patches of colored setae on the forewings. These characteristics all seem to represent the primitive state and should not be used to establish monophyly of the melleopicta group, although they can perhaps be used as diagnostic features to help identify species within the genus.

Character states distinguishing the Leucotrichia pictipes species group include males bearing 2 ocelli, either a brush of setae or a simple spine on sternum VII, a modified head (except for Leucotrichia imitator ) as discussed above under the generic description, and colored spots or linear setal patterns on the forewings. These characteristics, particularly the reduced number of ocelli and the modifications to the head, may represent synapomorphies for this group of species within the genus.

While the specialized members of the pictipes group may form a monophyletic species group, the same cannot be said with certainty of the members of the melleopicta group, as they share no synapomorphies that could unite them. Despite being much larger in terms of species numbers, no synapomorphic adult characters were found within the melleopicta group that could be used to support its monophyly or to divide it into monophyletic species groups. The 2 species groups, melleopicta and pictipes , are retained here for historical relevance. All species newly described here have 3 ocelli and are placed in the melleopicta species group, which is consistent with its definition.