Amphipsyche meridiana Ulmer 1909

Peumwarunyoo, Pronthip & Prommi, Taeng-On, 2013, Larvae of Amphipsyche species (Trichoptera: Hydropsychidae) from Thailand, Zootaxa 3635 (3), pp. 251-260 : 256-259

Amphipsyche meridiana Ulmer 1909

Head: Dorsum of head yellow to dark-brown. Frontoclypeal apotome and dorsal surface of head flattened. Surface of head dark brown dorsally, with 2 distinct P-shaped yellow marks surrounding eyes and extending mesad toward middle of frontoclypeal apotome but separated on meson. Muscle scars posterodorsally. Head with few long bristles close to eyes. Head with numerous tapered setae on dorsal regions ( Figs. 20 , 30 ). Frontoclypeus with anterior margin concave and entire; triangular posterior end touching carina. Anteclypeus with 4 large brown sclerites basally; distal part of anteclypeus membranous. Lateral and ventral surfaces of head yellowish ( Figs. 19–20 ). Genae ventrally with stridulatory lines mostly in anterior half close to mid-ventral suture ( Fig. 21 ). Labrum oval shape in dorsal view with large membranous basal region and large brushes on apicolateral lobes; anterior margin with dense fringe of hairs ( Fig. 20 ). Anterior ventral apotome subtriangular with lateral lobe rounded and posterior tip pointed; posterior ventral apotome small and spearhead-shaped ( Fig. 21 ). Submentum large, triangular, with bristles on its apical margin ( Fig. 21 ). Dorsal and ventral ridges of both mandibles each with bristles on outer margins. Ventral blade of left mandible with blunt, basal tooth and 3 apical teeth; ventral blade of right mandible with 2, blunt, basal teeth and 3 apical teeth and dorsal blade with 1 apical tooth ( Fig. 23 ).

Thorax: Thoracic nota light brown with numerous tapered primary setae ( Fig. 34 ). Pronotum divided into 2 sclerites by median ecdysal line, with pair of short setae on either side of mid-line ( Fig. 23 ). Meso- and metanota each with median black mark on posterior margin: mesonotal mark large and crescentic; metanotal mark small and irregular in shape ( Figs. 24–25 ). Meso- and metanotal sclerites each with 3 pairs of long setae ( Figs. 24–25 ). Mesosternum with pair of tracheal gills; metasternum with 2 pairs. Transverse prosternite with transverse brown stripe, posterior margin with large, triangular median sulcus, sclerotized, with small and transparent plate on midposterior margin ( Fig. 26 ). All legs stout, equipped with spines, bristles and soft, tapered setae. Forelegs each with single, pointed trochantin and single coxal scraper on inner margin ( Figs. 27–29 ).

Abdomen: Abdominal segments with numerous tapered setae. Abdominal segments I and II each with row of hooks on tergum ( Figs. 32–33 ). First segment with 3 pairs of gills on sternum; gill bases placed adjacently. Segments II–VI each with 6 pairs of gills. Segment VII with 5 pairs of gills. Segment VIII with 2 pairs of gills ( Figs. 19 , 31 ). Sternum IX with pair of large ventral sclerites equipped with long bristles on posterior margins; with row of bristles on each ventrolateral surface (Fig. 36). Anal prolegs long and well-developed, each bearing cluster of long bristles and right-angled anal claw; dorsal surface of each proleg sclerotized (Fig. 36).

Diagnosis: This species may be distinguished from Amphipsyche gratiosa on the basis of the following combination of characteristics. Firstly, the frontoclypeal apotome has 2, separated, P-shaped, yellow marks. Secondly, abdominal gills each have a central stalk with numerous lateral filaments. Lastly, the average head length and width of Amphipsyche meridiana are longer than those for Amphipsyche gratiosa .

Material examined: THAILAND: Lopburi Prov.: Pasak Jolasit Dam outlet, 2-vii-2008, Prommi, 453 larvae, 56 male pupae, 1033 male adults; same locality, 2-viii-2008, Prommi, 426 larvae, 29 male pupae, 859 male adults; same locality, 2-ix-2008, Prommi, 298 larvae, 13 male pupae, 563 male adults; same locality, 2-x-2008, Prommi, 102 larvae, 9 male pupae, 605 male adults.

Discussion: Amphipsyche larvae differ from Macrostemum in having an anteclypeus with 4 basal sclerites rather than 2, and a frontoclypeus which does not extend beyond the carina. Amphipsyche occur from Sri Lanka and India eastward to China and through Java, Sumatra, Borneo and the Philippines. Barnard (1984) revised Amphipsyche adults and Ulmer (1957) gave detailed descriptions of the larvae from Java and Sumatra. In this study, A. gratiosa larvae were generally found on stony substrates in the middle reach of fast-flowing rivers and streams, whereas A. meridiana larvae were often associated with dams and impoundments where they reach high densities (Boon 1979). Seshadri (1955) recorded the nuisance caused during the monsoon by swarms of adult Amphipsyche emerging from channels downstream of a dam in India.

Amphipsyche nets consist of coarse silk strands that can withstand high current speeds. In addition, the nets do not collapse when flow velocities decline. At high densities, larvae exhibit unusual cooperative behavior and build large communal nets (Boon 1979).

Figures

FIGURES 19 – 22. Larva of Amphipsyche meridiana: 19, larva, right lateral view; 20, head, dorsal view; 21, head, ventral view; 22, mandibles, dorsal view.

FIGURES 30 – 35. SEM images of Amphipsyche meridiana: 30, head, dorsal view; 31, abdominal gills, right ventrolateral view; 32, row of abdominal hooks on segment I, dorsal view; 33, abdominal hooks, dorsal view; 34, setae on pronotum, dorsal view; 35, anal prolegs, ventrocaudal view.

FIGURES 23 – 29. Larva of Amphipsyche meridiana: 23, pronotum, dorsal view; 24, mesonotum, dorsal view; 25, metanotum, dorsal view; 26, prosternum (arrow point); 27, right foreleg, a right lateral view of the lateral (posterior) face with coxal scraper (arrow point); 28, right midleg, a right lateral view of the lateral (posterior) face; 39, right hindleg, a right lateral view of the lateral (posterior) face.