Mejicanotrichia harrisi Bueno-Soria & Barba-Alvarez , 1999

Ramirez-Carmona, Mauricio, Barba-Alvarez, Rafael, Contreras-Ramos, Atilano & Rivas, Gerardo, 2022, Larval and female descriptions of Mejicanotrichia Harris & Holzenthal, 1997 (Trichoptera, Hydroptilidae, Leucotrichiinae) from Mexico, ZooKeys 1111, pp. 355-369 : 355

Mejicanotrichia harrisi Bueno-Soria & Barba-Alvarez, 1999

Figs 1A-C , 2A-D

Material examined.

25 larvae (IN-TR-00221). Mexico, Guerrero, Tonalapa del Río, Tonalapa River, near the Atlmolonga “balneario” (780 m a.s.l., 18°20'57.05"N, 99°42'10.12"W), 25 January 2020; leg. M. Ramírez-Carmona and O. Lagunas-Calvo.

Diagnosis.

Abdomen mainly membranous with presence of abdominal tergites and fine pigment spots (Fig. 1A ). Propleural sclerite with irregular shape (Fig. 1B ) compared to M. tridentata , also the abdomen is wider in appearance. The size of the mature larvae of M. harrisi (2.1 mm) is smaller compared to the other species of Mejicanotrichia . The propleural sclerite has the form of a "serrated tooth" unlike the other species of the genus (Figs 1B , 4B ; Bowles et al. 1999). Additionally, the abdominal dorsal tergites are wider and shorter than in M. tridentata , which exhibits a larger number of setae over the tergites than M. harrisi .

Description.

Dorsoventrally depressed body, range length: 1.9-2.1 mm, covered extensively by colorless and thick setae (Fig. 1A ). Dorsum covered almost entirely by fine pigments spots (ornamental) (Fig. 1C ), which give it the appearance of “sandpaper” (Fig. 2A ). Larval case absent until before pupation.

Head. Dark brown, prognathous, without visible ecdysial sutures. Antennae simple (Fig. 2B ).

Thorax. Pro-, meso-, and metanotum divided by a median ecdysial line (Fig. 1A ), with a lateral process with two thick and colorless setae except on pronotum. Pronotum anteriorly elongated, subsequently widened, longer than meso- and metanotum, covering much of the head; anterolateral corners folded towards the ventral region. The anterior pronotal margin with a row of thick and opaque setae. Propleural sclerite well developed and strongly dark, subtriangular (Fig. 1B ). Prothorax with a pair of ventral sclerites, each with an oval to subrectangular shape. Meso- and metathorax covered with thick, short, colorless setae. Lateral margins thickly darkened, appearing with a longitudinal bar (Fig. 1A ). Anterior margins of both nota with a row of opaque setae, in a smaller proportion than the pronotum. First pair of legs slightly shorter than the others. The three pairs of legs each with two rows of fine and moderately long setae on tibiae and tarsi, with well-developed tarsal claws.

Abdomen. Long and wide, gradually tapering posteriorly. Venter with thick and extremely short setae irregularly distributed on surface. Segments I-VIII with well developed, short and wide tergites, covering much of each notum, those on segment I differing noticeably in size and shape from remainder. All tergites with thick and short colorless setae. Tergite I divided in two by a median line, with two thin and dark setae on the anterior margin. Tergites II-VII with medial lacunae and two fine and dark setae in the posterolateral margin (Figs 1A, C , 2C ). Posterior and anterior margins of tergites with thick, short, and colorless setae, well distributed along both margins. Fine pigment spots more evident on integument around tergites (Fig. 1C ). Middle of anterior margin of tergites III-VI, with two flattened projections. Lateral projections of abdomen without tergites, but lateral margins bear a continuous row of slightly thick, long, colorless setae (Fig. 2D ); one seta noticeably longer than the others, arising at apex of each lateral projection. Segment IX strongly narrowed, posterior margin with four thick and opaque setae, two rows of thick setae in the middle. Anal prolegs prominent, cylindrical, projecting posteriorly, with well-developed anal claws curving ventrally (Fig. 1A ).

Comments.

The specimens were collected at a water temperature of 19 °C; with pH between 7.8-8.4; water presented a hardness of 171 mg CaCO3/l; the dissolved oxygen was 7.6 mg/l and 89% of oxygen saturation.

Figures

Figure 1. Larva of Mejicanotrichia harrisi Bueno-Soria & Barba-Alvarez, 1999 A habitus, dorsal B propleural sclerite C tergite of abdominal segment V, dorsal. Scale bars: 1 mm (A); 80 µm (B); 130 µm (C).

Figure 2. Scanning electron micrographs of larva of Mejicanotrichia harrisi Bueno-Soria & Barba-Alvarez, 1999 A habitus, dorsal B antenna C lacunae of abdominal segment V D lateral projection of abdominal segment V. Scale bars: 200 µm (A); 10 µm (B, C); 50 µm (D).

Figure 4. Larva of Mejicanotrichia tridentata (Bueno-Soria & Hamilton, 1986) A habitus, dorsal B propleural sclerite C tergite of abdominal segment V, dorsal. Scale bars: 1 mm (A); 65 µm (B); 80 µm (C).