Cheumatopsyche Wallengren 1891

Zhang, Ao & Zhou, Xin, 2021, The larvae of Chinese Hydropsychidae (Insecta: Trichoptera), Part II: Potamyia chinensis and Cheumatopsyche trifascia, Zootaxa 4926 (4), pp. 547-558 : 553-554

GENUS Cheumatopsyche Wallengren 1891

Cheumatopsyche larvae are typically small and may lack conspicuous diagnostic characters among species. Some general larval characters considered useful in previous studies (e.g., Statzner 1984) include the shape and number of notches on the front margin of the frontoclypeus; the shape of the foretrochantins, especially the shape of the dorsal branch; the shape of the submentum; the morphology of primary seta 3 on the frontoclypeus; the shape of the posterior prosternal sclerites; characters of the secondary setae, and the morphology of the stridulating files. In addition, Schefter and Wiggins (1987) promoted the use of secondary setae located on the head, thoracic nota and abdominal segments in diagnoses of Cheumatopsyche larvae.

A total of 29 Cheumatopsyche species have been recorded from China ( Yang et al. 2016). While only the larva of C. ventricosa was illustrated ( Dudgeon 1999), the larval stage of C. spinosa was readily recognized in a life history study ( Dudgeon 1997). In the present work, seven Chinese Cheumatopsyche species were studied for possible larval-adult associations using DNA sequences, among which one species ( C. trifascia ) was successfully associated following Zhou et al. (2007) ( Table 1; Fig. 1 ). Meanwhile, the other six species remained unassociated because the identification of adults was in progress, or the larvae (HPGPs 6–11, Figs, 1a, 1b) or adult males (HPGP 5, Figs. 1a, 1b ) were not available to this study. However, both D2 and COI fragments appear able to provide enough nucleotide variation among Cheumatopsyche species to enable future associations. A single larva (CNCAD_0016) had identical D2 sequence with an adult male (CNCAD_0134), which was tentatively identified as C. nr. infascia (HPGP 12, Fig 1b ). However, this larva was not considered successfully associated because its COI sequence showed differences from that of the adult, therefore violating the stringent criteria proposed by Zhou et al. (2007). The larvae of Cheumatopsyche are among the most abundant caddisfly larvae in many stream systems. Yet, the difficulties in identifying species of both adults and larvae make them one of the most challenging groups in freshwater ecological research and biomonitoring projects. The DNA association approach used in this work could play an important role in future larval-adult association and species identification for the genus.

Generic characteristics of the genus. Larva generally small; head and thoracic nota often lacking prominent marks. Head bearing dense, short, tapered hair-like setae, no blunt-setae. Anterior margin of frontoclypeal apotome with or without median notch (usually with a notch). Mediotransversal fold of frontoclypeus and tentorial pits not pronounced. Anterior ventral apotome subtriangular. Posterior ventral apotome minute, triangular. Submentum trapezoidal with anterior margin cleft. Seta 22 on anterolateral corners of pronotum prominent, long. Prosternal plate large, followed posterolaterally by pair of posterior sclerites usually minute. [The North American species C. etrona Ross 1941 has large posterior sclerites ( Wiggins 1996)]. Foretrochantins forked. Metasternum with three ventral gills: single ventromesal tracheal gill in addition to pair of coxal (lateral) gills—based on C. trifascia and African species C. thomasseti (Ulmer) . [But see Scott (1983) for number of metasternal gills in Cheumatopsyche .] No scalehairs on abdominal segments. Abdominal segment VII with or without ventral gills.

Figures

FIGURE 1. Larval-adult association of Chinese Potamyia and Cheumatopsyche species. 1a, COI Maximum Likelihood phylogram; 1b, D2 Maximum Likelihood phylogram. L = larva; M = adult male. Bootstraps values are shown below stems; values less than 75 are not shown in the phylograms.