Chimarra (Otarrha) ramosa, Holzenthal & Blahnik & Ríos-Touma, 2022

Holzenthal, Ralph W., Blahnik, Roger J. & Rios-Touma, Blanca, 2022, A new genus and new species of Ecuadorian Philopotamidae (Trichoptera), ZooKeys 1117, pp. 95-122 : 95

Chimarra (Otarrha) ramosa sp. nov.

Figs 12 , 13

Type material.

Holotype. Male (pinned). Ecuador: Orellana: river, road between Wawa Sumaco and Loreto [UV], 0.73632°S, 77.49507°W, 610 m a.s.l., 11.iii.2020, Ríos, Holzenthal, Frandsen, Pauls, Amigo, UMSP000501575 (UMSP). Paratypes. Ecuador: same data as holotype, 6 males (pinned) (UMSP), 5 males, 1 female (in alcohol) (MECN); Pastaza: small stream ca. 3.8 km (rd) SE Cuwitayo, 1.92251°S, 77.79459°W, 703 m a.s.l., Ríos, Holzenthal, Frandsen, Errigo, Amigo, 2 females (pinned) (UMSP).

Diagnosis.

This is a species in the Chimarra (Otarrha) patosa group, as defined by Blahnik (2002). Other species belonging to this group include C. amazonia Blahnik, 2002, C. parene Blahnik, 2002, C. parilis Blahnik, 2002, C. particeps Blahnik, 2002, C. patosa Ross, 1956, and C. peruana Blahnik, 2002. Like other members of the group, it has tine-like projections from the mesal margin of the inferior appendages. It is the 1st member of the group known from Ecuador; all others in the group have known distributions confined to Peru. Like C. patosa and C. peruana , the new species has distinct, digitate projections from the posterior margin of tergum VIII; however, they are much shorter than in either of those species and the apical spines are very short and inconspicuous (Fig. 12A, B ). Other distinctive aspects of the new species include additional spine-like projections from the inferior appendages, both basally and apically (Fig. 12C, D ), and a single pair of very short phallic spines (Fig. 12E ), much shorter and less conspicuous than those of other species in the group. Chimarra amazonia also has spine-like basal projections on the inferior appendages and, on this basis, as well as the presence of very short dorsal projections on tergum VIII, is the likely sister taxon of C. ramosa .

The genitalia of the female of Chimarra (Otarrha) ramosa closely resemble those of C. parilis and C. particeps , particularly in that the ventral margin of segment VIII is somewhat produced and subtruncate, but has a distinct, shallow, U-shaped mesal invagination, bordered on either side by ventral setal warts composed of several elongate submarginal setae (Fig. 13A ). It is most readily diagnosed by a very elongate V-shaped sclerite in the vaginal apparatus, most distinctly evident in ventral view (Fig. 13C ).

Description.

Adult. Forewing length male 3.9-4.3 mm (n = 5); female 4.7-5.0 mm (n = 2). Color nearly uniformly brownish black (fuscous). Chord of forewing hyaline, linear, indistinct. Palps short. Head relatively flat, moderately elongate (postocular parietal sclerite ca. half diameter of eye).

Male. Tergum VIII with pair of digitate projections from posterior margin, ca. as long as tergum, apices slightly dilated, with very short spines. Segment IX, in lateral view, with anterior margin nearly straight (slightly expanded in ventral half), segment longest ventrally, just above ventral process, posterior margin obliquely, nearly linearly, narrowed dorsally; posteroventral process relatively elongate (length more than 2 × width), nearly uniform in width, apex subtruncate, acute apicodorsally. Mesal lobe of tergum X (or posteromesal projection of tergum IX) very narrow and relatively short, less than half length of lateral lobes of tergum X, distinctly sclerotized, pre-apically with short, acute dorsal projection. Tergum X divided mesally, forming two sclerotized lateral lobes, narrowly separated to base; lateral lobes, as viewed laterally, each with apical invagination, extending nearly half length of segment and forming narrow, apically acute, dorsal and ventral lobes; dorsal lobe slightly shorter than ventral lobe and more strongly sclerotized, with scattered sensilla, except apically, beginning from base of lateral invagination, dorsally with three or four short setae; dorsal lobe with apex narrowed, strongly sclerotized, and distinctly downturned, ventral lobe rather weakly sclerotized, except apically, apex slightly upturned. Preanal appendage relatively large, flattened, ear-like. Inferior appendage elongate, narrow, mesally curved, tapering apically, apex inturned and acute; mesal surface with several tine-like projections: basal tine short and acute, spine-like, median tine very elongate, narrow, distinctly evident in lateral view, somewhat flexed or bent basally, pre-apical tine short and somewhat irregular in shape. Phallic apparatus with phallobase relatively short and tubular, with basodorsal expansion, distinctly ventrally flexed on ventral margin; endotheca with membranous, sack-like basodorsal lobe, lacking spines, apex of endotheca dilated, with two very short, closely apposed, subequal dorsal spines or sclerites. Phallotremal sclerite complex composed of moderately elongate rod and ring structure, with pair of short, weakly sclerotized, apicoventral sclerites.

Female. Segment VII with short, rounded ventral process near posterior margin. Segment VIII short, synscleritous; anterolateral margin very obtusely angular, with a weakly developed apodeme at ca. mid-height; posterior margin, as viewed laterally, with dorsal setal wart absent, lateral setae on a broadly rounded protrusion in ventral half, composed of marginal array of elongate setae; ventral margin of segment distinctly produced, in ventral view forming subtruncate projection with shallow posteromesal invagination, bordered on either side by ventral setal warts, each composed of more or less linear array of several elongate submarginal setae; dorsal margin of segment very short, but continuously sclerotized. Tergum IX short and very wide, with short, ventrally projecting, anterolateral apodemes; posterior margin with rounded mesal projection bearing cluster of short setae; sternum IX absent or not evident. Tergum X forming pair of subdivided lobes, each with short apical cercus; basal part of lobe large, distinctly sclerotized, and setose; apical part of lobe more weakly sclerotized, with ventromesal tract of short setae. Vaginal apparatus short, with distinct anteromesal cup-like sclerite and longitudinal anterior sclerites, including very elongate, narrowly V-shaped, posteromesal sclerite.

Etymology.

From the Latin ramus, meaning branches or antlers, and referring to the very branched inferior appendages of the male genitalia.

Habitat notes.

The small stream in Pastaza where paratypes were collected had a flow of 0.05 m3/s, a specific conductivity of 60 µS /cm, oxygen saturation was 90.7%, and daytime water temperature was 23.2 °C at the time of collection.

Figures

Figure 12. Chimarra (Otarrha) ramosa sp. nov. Male genitalia A segments VIII-X, lateral B segments VIII-X, dorsal C inferior appendage, segment IX, ventral D inferior appendage, dorsal E phallus, lateral.

Figure 13. Chimarra (Otarrha) ramosa sp. nov. Female genitalia A segments VII-X, lateral B segments IX, X, dorsal C segment IX, X, vaginal apparatus, ventral.