Eubasilissa maclachlani White 1862

Panich-Pat, Thanawan & Prommi, Taeng On, 2021, The larva of Eubasilissa maclachlani White 1862 (Trichoptera: Phryganeidae) from Thailand, with notes on its biology, Zootaxa 5081 (2), pp. 286-294 : 287-288

Description of Eubasilissa maclachlani White 1862

( Figs 2–13 )

Final instar larva: Total length 40–45 mm (N = 4). Background color of head and notal sclerites yellowish-brown to reddish-brown ( Fig. 2 ).

Head: Head capsule width 3–4 mm (n = 4). Entire head ( Figs 3−4 ) yellowish-brown with median reddish-brown band on frontoclypeal apotome, median band extending from anterior margin to posterior angle of frontoclypeal apotome, suddenly wider posterior of setae no. 5; small pale spot surrounding base of each seta no. 11, 14, and 17 ( Fig. 3 ); small dark muscles scars evident on posterior half of head ( Figs 3−4 , 6 ). Labrum ( Fig. 3 ) with anterolateral brushes of hairs, setae no. 5 and setae no. 6 longer than other setae. Right mandible ( Figs 3−4 ) triangular with acute apex, one blunt dorsal tooth and two ventral teeth on mesal margin, left mandible triangular with 3 teeth; basolateral margin of each mandible with 2 pairs of long setae. Labium ( Fig. 4 ) with submental sclerite forming lightly sclerotized, V-shaped strap; maxillary lobes each represented by a slender finger-like process mesal of its maxillary palp; transverse cardines ( Fig. 4 ) triangular; ventral apotome ( Fig. 4 ) narrowly triangular.

Thorax: Pronotum ( Figs 6 , 9 ) yellowish-brown with black posterior margin; several pairs of short and long setae along lateral and anterior margins and on pronotal surface; pale muscle scars present near posterior edge; prosternal horn ( Fig. 7 arrow) and dark triangular prothoracic sternellum present. Mesonotum ( Figs 6 , 9 ) largely membranous; large mesonotal sa 1 sclerites contiguous mesally; mesonotal sa 2 sclerites present but very small and separate; mesonotal sa 3 sclerites ovoid, each with 12–14 long setae. Metanotal setae in positions sa 1 and sa 2 each have small, sclerotized area around base ( Figs 6 , 9 ); metanotal sa 3 sclerites ovoid, each bearing 10 long setae.

Legs brown ( Figs 10−12 ); forelegs somewhat raptorial, each with forefemur broad, flat; midfemur broader than hind femur, but narrower than forefemur; lower edges of trochanters and femora each with row of fine setae (arrows). Coxal combs small, each comb appearing as tiny, raised, transverse band (individual teeth not evident at 50X magnification), combs distributed over much of mesoventral surfaces of fore- and midcoxae ( Fig. 13 , arrows).

Abdomen: First abdominal segment with three well-developed humps (one dorsal and two lateral) ( Figs 2 , 8, 9 , arrows). Abdominal gills single on segments I to VIII ( Table 1 ). Lateral fringe on each side of segments III to VIII ( Fig. 8 , arrows). Tergite IX ( Fig. 14 ) heart-shaped with reddish brown dots (arrow); with 4 pairs of setae, mesal pair longest, lateral pair about one-third as long as mesal pair. Abdominal segment X lateral sclerite ( Fig. 14 ) with reddish-brown markings, and lateral and posterodorsal setae; basal tuft consisting of 3 stout, longer setae; anal proleg claw ( Fig. 14 ) with 2 accessory hooks ( Fig. 15 , arrow).

Larval case ( Fig. 5 ) of Eubasilissa maclachlani of 5 ring-like sections of rectangular leaf pieces fastened side by side, with rings joined end to end. Length of larval case up to 40 mm.

Material examined: THAILAND: PHITSANULOK PROV.: Phu Hin Rong Kla National Park, Mhun Daeng Noi stream, 1600 m a.s.l., 16°57’ N, 101°03’ E, 17-i-2003, 3 larvae, 1 male adult, leg. Viteepradit. CHIANG MAI PROV.: Doi Inthanon National Park, Siriphum Waterfall , 1380 m a.s.l. 18°32’ N, 98°31’ E, 13-i-2003, 1 larva, 1 male adult, leg. Thamsenanupap.

Bionomics. The larval specimens of E. maclachlani were collected from slowly flowing streams where leaves accumulated ( Fig. 1 ). The water temperature was under 20ºC on average ( Malicky & Chantaramongkol 1993; Changthong & Chantaramongkol 2005; Thamsenanupap 2005). An annual physicochemical analysis revealed that larvae grow in well-oxygenated (7.63 mg /L) and low-mineralized waters with a pH range of 5.8–6.8, alkalinity of 1.80 mg /L, and nitrate nitrogen, orthophosphate, and ammonia nitrogen of 0.9, 0.05, and 0.31 mg /L, respectively. The turbidity of water was 15.25 NTU. The guts of the larvae contain leaf fragments. Larvae of E. maclachlani can be found throughout the year in various instars ( Changthong & Chantaramongkol 2005), but the adult stage was only found in the cool months (November to January) ( Thamsenanupap 2005). Himalopsyche acharai Malicky & Chantaramongkol 1989 , Rhyacophila petersorum Schmid & Denning 1971 (in Denning & Schmid 1971), Arctopsyche hynreck Malicky & Chantaramongkol 1991a , Trichomacronema paniae Malicky & Chantaramongkol 1991b , and Ugandatrichia maliwan Malicky & Chantaramongkol 1991a , are other caddisfly species that appear together with E. maclachlani ( Thamsenanupap 2005) .

Figures

FIGURE 1. Sampling site of Mhun Daeng stream: Upper (1A) and lower (1B) parts of the collecting site.

FIGURES 2−5. Larva of Eubasilissa maclachlani White 1862: 2, habitus, right lateral; 3, head, dorsal; 4, head, ventral; 5, larval case.

FIGURES 6, 7. Larva of Eubasilissa maclachlani White 1862: 6, head and thorax, left dorsolateral; 7, head and thorax, ventral, showing prosternal horn (black arrow) and sternellum (white arrow).

FIGURES 8, 9. Larva of Eubasilissa maclachlani White 1862: 8, abdominal segments, left lateral, showing well-developed dorsal and lateral (paired) humps (arrows) on segment I and lateral fringe (paired) on segments III to VIII (arrows); 9, thorax and abdominal segment I, dorsal, showing meso- and metanotal setal areas (sa1, sa2, sa3) and dorsal and lateral humps of abdominal segment I (arrows).

FIGURES 10−15. Larva of Eubasilissa maclachlani White 1862: 10, outer (posterior) face of right foreleg, posterior, showing foretrochantin (vertical arrow) and row of fine setae (diagonal arrow); 10.1, base of right forecoxa, posterior; 10.1.1, apex of right forecoxa, dorsal. 11, inner (anterior) face of left midleg, anterior, showing row of fine setae (arrow); 11.1, base of right midcoxa, anterior; 11.1.1, right midcoxa, dorsal. 12, inner (anterior) face of left hind leg, anterior, showing row of fine setae (arrow); 12.1, inner (anterior) face of left hind coxa. 13, mesoventral surface of a forecoxa (inner) at 50X magnification, showing small coxal combs (arrows). 14, posterior end of abdomen, posterior, showing tergite IX and anal prolegs. 15, right anal claw, posterior, showing accessory hooks (arrow).