Diplectrona obscura Ulmer 1930
Creators: name: Zhou, Xin
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Trichoptera
Hydropsychidae
Diplectrona
Diplectrona obscura

description: Diplectrona obscura Ulmer, 1930
Figure 4a–k
LARVA (POSSIBLE ASSOCIATION)— Head. Head generally orangish brown, subquadrate, 1.4 mm long, 1.2 mm wide. Frontoclypeal apotome very broad, narrowed opposite eyes, behind which strongly expanded laterally.
Middle expansion as wide as anterior margin of frontoclypeus. Anterior margin of frontoclypeus smooth, slightly convex, without prominent flanges or teeth. Frontoclypeal apotome nearly flat, tentorial pits and mediotransversal crease not prominent (Fig. 4a). Dorsum of head (including frontoclypeus) densely covered by two types of secondary setae: long, thick, dark brownish blunt-setae and median to long, fine, tapered, dark hair-like setae (Fig. 4a). Blunt-setae erect, nearly perpendicular to surface of head capsule; hair-like setae lying close to surface, pointing cephalad. Posterior sixth of dorsum of head seta-less.
Eyes circled by whitish yellow area. Posterior seta-less area of head whitish yellow. Area on anterior fourth of frontoclypeus dark brownish, whose posterior border not conspicuous. Series of dark spots posterior to expansion of frontoclypeus, nearly U-shaped in arrangement. Parietal sclerites along frontoclypeal suture behind frontoclypeal expansion and along coronal suture with dark brownish thin stripes; contrasting with undarkened adjacent frontoclypeus. Muscle scars mostly confined to posterior areas of parietal sclerites, dark brownish, conspicuous (Fig. 4a). Anterior ventral apotome large, subtriangular, with anterior and posterolateral margins concave, anterior half of anterior ventral apotome dark. Posterior ventral apotome large, elongated, triangular, posterior border dark brownish. Anterior and posterior ventral apotome about same length, together longer than mid-ventral ecdysial line. Submentum smaller than anterior ventral apotome, trapezoidal; posterior margin curved; anterior margin short, not cleft, almost flattened; both anterolateral corners round.
Venter of head mostly yellowish orange. Stridulating files dark: anterior two-thirds relatively paler, brownish; posterior third dark brownish and extending laterodorsad to mid-regions of lateral sides of parietal sclerites. Stridulating files thickened, spaces between striae sparse. Each transverse striae on anterior twothirds of stridulating files consisting of series of short, longitudinal small ridges. Striae on posterior third closely spaced, consisting of short, broken, transverse ridges not clearly defined. Lateroventral sides of parietal sclerites bearing thick, long, acuminate setae and short, fine, tapered hair-like setae on anterior halves (Fig. 4b). Series of muscle scars on lateral sides of parietal sclerites dark, very conspicuous (Fig. 4c).
THORAX. Thoracic nota densely covered by long, thick, dark blunt-setae and short, fine, tapered hair-like setae. Pronotum yellowish orange; meso- and metanota dark brownish. Pronotum subdivided longitudinally in middle, constricted laterally at posterior border. Blackish marks along lateral borders not reaching anterolateral corners (Fig. 4e). Setae 22 on anterolateral corners inconspicuous, indifferentiable from regular blunt-setae. Prosternal plate large, folded ventrad at posterior third, with lateral borders strongly incised. Blackish marks along anterior border thinner near middle of each side. Posterior border of prosternal plate concave, bearing broad blackish mark, surrounded by reddish brown area. Posterior prosternal sclerites not present (Fig. 4f). Foretrochantins not forked, each bearing series of blackish, thick bristles (Fig. 4g). Forefemur with small triangular scraper on middle of dorsomesal surface (Fig. 4h), presumably functioning as stridulator rubbing against stridulating files on ventral side of head. Mesonotum with transverse ecdysial suture on posterior third, extending anterolaterad toward anterior third of lateral borders (Fig. 4e). Diagonal grooves pronounced, extending from anterolateral corners to near transverse suture. Posterior border bearing wide, flattened blackish U-shaped mark on middle two-thirds; this median mark connected laterally with lateral borders of mesonotum by thin, curved, blackish lines, with triangular brownish areas behind them (Fig. 4d). Metanotum with transverse ecdysial suture on posterior sixth, extending anterolaterad toward anterior third of lateral borders. Diagonal grooves not as pronounced as those on mesonotum. Posterior border bearing wide, thin blackish mark on middle two-thirds, not continuous with blackish marks along lateral borders (Figs. 4d, e). Mesosternum bearing pair of ventromesal gills; metasternum bearing pair of ventrolateral gills and single ventromesal gill (Table 4). Each thoracic tracheal gill with single stem.
ABDOMEN. Abdominal terga densely covered by thick, elongated, dark brownish club-hairs, with sparsely scattered short, fine, hair-like setae among them (Fig. 4i). Abdominal segments III–VII bearing simple, long, finger-like lateral gills on pleura (Fig. 4j). Abdominal segment III with one lateral gill; IV–VII with three closely arranged lateral gills on each side (Table 4). Abdominal sternum I bearing pair of single-stemmed ventral gills on each side (one lateral and one median), stems widely separated; segments II–V each bearing one bifid ventrolateral gill and one single ventromesal gill, with latter situated slightly anterior of former; VI bearing one ventrolateral and one ventromesal gill on each side, both single; VII–IX with no ventral gills (Table 4).
Ventral plates on abdominal segment VIII small, triangular, with yellowish pigmentation. Anterior part of each plate VIII with short, thickened, conical golden setae; posterior border with long, thick, blackish bristles, pointing posterolaterad. Area between plates VIII sclerotized and pigmented such that ventral plates on segment VIII appearing as single sclerite. Ventral plates IX large, nearly semi-circular, with lateral borders convex, mesal borders straight; yellowish. Golden setae on anterior part of each plate IX longer than those on plates VIII; series of variably long, thick, blackish bristles distributed along almost entire length of lateral border, pointing posterolaterad or posterad. Posteromesal corner of each plate IX without thickened golden setae. Thickened golden setae on anterior regions of ventral plates VIII and IX bearing prominent setal sockets (Fig. 4k).
Diagnosis. This species can be differentiated from other Chinese Diplectrona species by the presence of a series of dark muscle scars on the posterior whitish area of each parietal region.
Material examined. Guangxi: Long-lin County, Jin-zhong-shan Provincial Forest Preserve, Nong-heng Gou, ~ 1.3 km N of Xi-she Village. N24.57867, E104.91399. 1140 m. 11-June-2004. L-F Yang, X. Zhou, C. J. Geraci, K. Kjer, 8 specimens.
Thorax Abdominal segments
Dr. John Morse of Clemson University, USA, Dr. Karl Kjer of Rutgers University, USA, and Professor Lianfang Yang of Nanjing Agricultural University, China, have provided critical advice on this larval association work and made important comments on the manuscript. Changhai Sun of Nanjing Agricultural University, China, did crucial work on adult morphology. I especially appreciate the great assistance from the scientists and staff members of the following Chinese Nature Preserves: Nan-ling, Ding-hu-shan and Nankun-shan Nature Preserves of Guangdong Province; Cen-wang-lao-shan, Jin-zhong-shan, Jiu-wan-da-shan, Mao-er-shan and Shi-wan-da-shan Nature Preserves of Guangxi Province; Wu-yi-shan Nature Preserves of Jiangxi Province; and Li-zi-ping and Da-feng-ding Nature Preserves of Sichuan Province. Special thanks to Dr. Shaoying Liu of Sichuan Forestry Science Institute for his generous help organizing our Sichuan exploration in 2005. This work was supported by the National Science Foundation (NSF DEB-0316504). COI sequence analysis is supported by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC) and from Genome Canada through the Ontario Genomics Institute to Dr. Paul D. N. Hebert, Biodiversity Institute of Ontario, University of Guelph, Canada.
description: Published as part of Zhou, Xin, 2009, The larvae of Chinese Hydropsychidae (Insecta: Trichoptera), Part I: Arctopsyche shimianensis, Parapsyche sp. A, and Diplectrona obscura, pp. 1-17 in Zootaxa 2174 on pages 13-16, DOI: 10.5281/zenodo.189300