Oecetis angularis, Blahnik, Roger J. & Holzenthal, Ralph W., 2014

Blahnik, Roger J. & Holzenthal, Ralph W., 2014, Review and redescription of species in the Oecetis avara group, with the description of 15 new species (Trichoptera, Leptoceridae), ZooKeys 376, pp. 1-83 : 12-15

Oecetis angularis sp. n. Figs 3, 33, 47, Map 1

Diagnosis.

Oecetis angularis sp. n. is diagnosed by its intermediate size, coloration (yellow, with distinct forewing spots), weakly protruding, but angularly demarcated ventral lobe of the inferior appendage (Fig. 3A), and by having a phallobase with its ventral apex acutely angled (V-shaped), as viewed caudally (Fig. 3C). The ventral margin of the phallobase is arched rather than strongly bent, as viewed laterally. Other species in which the apex of the phallobase is V-shaped in caudal view include Oecetis metlacensis , Oecetis uncata sp. n., and Oecetis apache sp. n., all of which are slightly larger in size, darker in color (yellowish-brown or light brown), and have the phallobase more strongly arched or bent as viewed laterally, and Oecetis acciptrina , which is much smaller in size and has the phallobase very strongly bent or hooked near its apex as viewed laterally. Oecetis metlacensis and Oecetis apache additionally differ by having much less prominent forewing spots (absent in Oecetis apache ).

Despite the resemblance of the genitalia to the above mentioned species, in overall appearance (size, color and forewing spotting) Oecetis angularis probably more closely resembles Oecetis protrusa sp. n., Oecetis tumida sp. n., or Oecetis mexicana , sp. n., all of which differ in having the apex of the phallobase U-shaped in caudal view (although the shape of the apex may be somewhat difficult to discern in Oecetis tumida due to its bulbous expansion). A distinction can be made on the basis that the ventral margin of the phallobase is not “keeled” preapically in species described as having a U-shaped apex. The general shape of the inferior appendage in Oecetis angularis , with a weakly protruding ventral lobe, is most similar to Oecetis tumida , which is also similar in size; Oecetis tumida differs in having the ventral margin the phallobase noticeably convexly rounded preapically, as viewed laterally (Fig. 24B), somewhat as in Oecetis protrusa . In Costa Rica, where Oecetis angularis and Oecetis protrusa have been found together, Oecetis angularis is generally somewhat larger in size than Oecetis protrusa . In other parts of their ranges, however, size differences seem to be less apparent.

In size, color, and forewing spotting Oecetis angularis is also nearly identical to Oecetis punctata , with which it may co-occur. However, the differences in the shape of the inferior appendages of the males, as well as the arrangement of the crossveins of the chord, as discussed above for characters separating the Oecetis avara and Oecetis punctata groups, should readily distinguish them.

Adult.

Forewing length: male (9.3-10.8 mm); female (6.3-9.0 mm). Color pale yellowish to brownish-yellow (similar to Oecetis mexicana ); forewing spots distinct, spots at base of discal and thyridial cells large or moderately large, other spots smaller; veins of forewing chord widely spaced, s and r-m veins slightly closer; chord with small spots at juncture of major veins, spots at opposite ends of chord larger; spots at apices of major veins small, pigmentation confined to vein. Setae along veins in apical part of forewing elongate, semi-prostrate, laterally diverging. Fringe of setae along costal margin of forewing moderate in length, somewhat projecting, not conspicuously erect.

Male genitalia.

Segment IX very short, with elongate setae along posterolateral margin. Preanal appendage moderately elongate, simple in structure, apical setae more elongate. Tergum X with elongate, narrow, deflexed mesal lobe, apex of lobe slightly enlarged, with numerous small sensilla; mesal lobe continuous basoventrally with short, paired lateral membranous or lightly sclerotized projections. Inferior appendage with prominent rounded dorsal process and angularly projecting ventral process; ventral process not strongly projecting, forming an approximate right angle with dorsal process; basomesal projection rounded, moderately prominent, with short, stout mesally directed setae; dorsal process with stout, ventrally curved setae; base of appendage, as viewed ventrally (Fig. 3E), distinctly angled. Phallobase short and tubular basally, with relatively elongate, arched ventral apex; apex, as viewed caudally, with ventral margin sharply V-shaped and slightly keeled (Fig. 3C); phallotremal sclerite elongate, prominent.

Holotype.

Male(pinned), COSTA RICA: Puntarenas: Río Bellavista, ca. 1.5 km NW Las Alturas, 8°57.060'N, 82°50.760'W, el 1400 m, 16-17.iii.1991, Holzenthal, Muñoz, Huisman (UMSP) (UMSP000208089).

Paratypes.

GUATEMALA: Suchitepequez: Finca Moca, 12.vi.1966, Flint & Ortiz, 1 male, 1 female (pinned) (NMNH); Puente Ixtacapa, 18-19.vi.1966, Flint & Ortiz, 1 male (pinned)(NMNH); COSTA RICA: Arenal, Quebrada Trondorancito, 24.vii.1967, O. S. Flint, Jr., 13 males, 9 females (pinned) (NMNH); La Suiza, 17.vi.1967, Flint & Ortiz, 1 male (pinned) (NMNH); Río Seco, NW Esparta, 28.vii.1967, O. S. Flint, Jr., 1 male (alcohol) (NMNH); Alajuela: Reserva Forestal San Ramon, Río San Lorencito and tribs., 10°12.960'N, 84°36.420'W, el 980 m, 30.iii.-1.iv.1987, Holzenthal, Hamilton, Heyn, 1 male (alcohol) (UMSP); Río Pizote, ca. 5 km N Dos Ríos, 10°56.880'N, 85°17.460'W, el 470 m, 9.iii.1986, Holzenthal & Fasth, 1 male (pinned), 16 males, 15 females (alcohol) (UMSP); Cartago: Río Reventazón in CATIE along Sendero Espaveles, 9°53.580'N, 83°39.060'W, el 500 m, 22.iii.1991, Muñoz, 5 males, 2 females (pinned), 1 male (alcohol) (UMSP); Limón: Río Banano, 16 km WSW Bomba, 9°52.280'N, 83°10.020'W, el 150 m, 26.iii.1987, Holzenthal, Hamilton, Heyn, 2 males, 2 females (pinned) (UMSP); Río Telire and small trib., SE Suretka, 9°33.240'N, 82°53.520'W, el 48 m, 1.ii.1986, 1 male, 1 female (pinned) (UMSP); Res. Biol. Barbilla, Río Dantas, 9°59.640'N, 83°26.580'W, el 300 m, 27-30.i.1992, Holzenthal, Muñoz, Kjer, 7 males (alcohol) (UMSP); Puntarenas: same data as holotype, 15 males, 8 females (pinned) (UMSP); Río Cotón in Las Alturas, 8°56.280'N, 82°49.560'W, el 1360 m, 18.iii.1991, Holzenthal Muñoz, Huisman, 18 males, 7 females (pinned), 10 males, 18 females (alcohol) (UMSP); same location, 12.viii.1990, Holzenthal, Blahnik, Muñoz, 7 males, 1 female (pinned), 8 males (alcohol) (UMSP); Río Jaba, 2.4 km (air) NW San Vito, 8°49.920'N, 82°59.460'W, el 970 m, 13.vi.1986, Holzenthal, Heyn, Armitage, 1 male (pinned), 1 male, 1 female (alcohol) (UMSP); Río Ceibo, route 2, ca. 6 km W road to Buenos Aires, 9°8.940'N, 83°22.620'W, el 250 m, 20.ii.1986, Holzenthal, Morse, Fasth, 1 male (alcohol) (UMSP); Río Singri, ca. 2 km (air) S Finca Helechales, 9°3.420'N, 83°4.920'W, el 720 m, 21.ii.1986, Holzenthal, Morse, Fasth, 10 males, 20 females (alcohol) (UMSP); ECUADOR: Cotopaxi: Latacunga, 133 km W, 2.vii.1975, el 1080 m, A. Langley & J. Cohen, 1 male (pinned) (NMNH); Quevedo, 36 km NE, el 335 m, 2.vii.1976, J. Cohen, 9 males, 4 females (alcohol) (NMNH); Loja: Río Puyango, el 300 m, 17-18.viii.1977, L. E. Peña G., 2 males, 1 female (pinned) (NMNH); Pichincha: Santo Domingo de los Colorados, 14. km E, 5.vii.1975, Langley & Cohen, 1 male (pinned) (NMNH).

Etymology.

This species is named Oecetis angularis for the acutely angled ventral apex of the phallobase, as seen in caudal view.