Hydropsyche Pictet, 1834

Oláh, J. & Johanson, K. A., 2008, Generic review of Hydropsychinae, with description of Schmidopsyche, new genus, 3 new genus clusters, 8 new species groups, 4 new species clades, 12 new species clusters and 62 new species from the Oriental and Afrotropical regions (Trichoptera: Hydropsychidae), Zootaxa 1802, pp. 1-248 : 56-57

Hydropsyche Pictet

Hydropsyche Pictet, 1834: 199 .

Type species: Hydropsyche cinerea Pictet, 1834 , synonym of H. instabilis Curtis, 1834: 213 ; subsequent selection by Ross (1944): 86. [ Curtis (1836): 601 and Westwood (1840): 49 selected Philopotamus instabilis Curtis as the genotype of Hydropsyche ; this designation is however invalid, instabilis not being originally included in the genus]

Symphitopsyche Ulmer, 1907 , new synonym

Plesiopsyche Navás, 1931 ; Ross & Unzicker 1977: 304 (as synonym of Symphitopsyche ).

Mexipsyche Ross & Unzicker, 1977 , new synonym

Ceratopsyche Ross & Unzicker, 1977 , new synonym

Herbertorossia Ulmer, 1957 , new synonym

Remarks: For Ceratopsyche , the type species is Hydropsyche bronta Ross which is now member of the Hydropsyche morosa species group. Ceratopsyche was described originally by Ross & Unzicker as a subgenus of Symphitopsyche . Ceratopsyche received full generic status by Nielsen (1981). The Hydropsyche morosa species group was erected from the bifida group of Ross (1944) by Schefter & Wiggins (1986) when Hydropsyche bifida Banks was designated a junior synonym of H. morosa Hagen ( Schefter & Unzicker 1984) .

The type species of Herbertorossia is Hydromanicus ungulatus Ulmer with type locality New Guinea. There are no differences between “ Herbertorossia ” and Hydropsyche among the primary generic characters, even the median cell of the hind wings is always closed. The short maxillay palp segment V is a secondary generic character and occurs, although sporadically, in other Hydropsyche species , as well as in other genera, i.e. Hydronema and Schmidopsyche . The asymmetrical and enlarged pretarsal claw is a secondary generic character occurring sporadically among hydropsychines. The genus is transferred to Hydropsyche in the Hydropsyche ungulata species group.

With around 400 species, Hydropsyche is one of the largest recognized caddisfly genera, with almost worldwide distribution. They are medium-sized, with little pronounced forewing irrorations, maculations and reticulations. The genus is the only one in the Hydropsychinae having closed median cell in the hind wings, except in Hydronema spp. However, there are sporadically occurring species in the many species groups with an open hind wing median cell. Their placement in a particular species group is demonstrated by their exhibi- tion of the same, well-defined, phallic apparatus as that of their respective species group. In the Hydropsyche genus cluster, only Hydropsyche has retained 5 primitive states of the primary generic characters: (2) proepisternal setal wart present; (3) forewing crossveins m-cu and cu separate; (4) hind wing median cell closed; (6) spur formula 244; and (7) hind wing forks 1235 present. The genus has only 2 derived characters: (1) reduced elongated preanal appendages, and (5) loss of crossvein m-cu in the hind wings, with the stems of M and Cu running very close.

In Hydropsyche there are several species with secondary reductions and parallelism not present in the vast number of related species:

1. An asymmetrical pretarsal claw, laterally flanked by setal bundle. This is a derived character of Hydropsyche , but a symmetrical pretarsal claw, without a laterally flanked setal bundle is found in Hydropsyche keoda , new species.

2. A primitive character in Hydropsyche is the separate forewing Sc and R1. All the examined specimens of the widely distributed H. pallipenne Banks from India and Malaysia have a deviation from this venation. In this species the Sc and R1 veins converge immediately before intersecting with the wing margin. The venational state is similar in H. trimonticola Mey , H. minutanga , new species, and H. binaria Mey.

3. A primitive character for Hydropsyche is the presence of a closed forewing and hind wing median cell. However H. tanua , new species and H. keralana , new species have open median cell in the hind wings. Furthermore, H. kozhantschikovi Martynov , H. valvata Martynov and H. orientalis Martynov have frequently open median cell in the hind wings, even in individuals from the same locality.

4. In the genitalia, the endophallus is usually broad and attached to the dorsum of the phallotheca in the Hydropsyche pluvialis species group. However, the endophallus is narrow and runs free in all individuals of H. kaznakovi Martynov examined from Pakistan.

The principle of grouping Hydropsyche species into species groups follows the possible trend of phallic evolution from the simple membranous, to the various complexities of the sclerotized phallothecal terminalia. The membranous endotheca, that evolved into various forms of endothecal processes and spines, is believed representing a primitive state compared with derived species characterized by having sclerotized structures. The primitive condition is represented by a large endotheca surmounted on phallothecal terminalia, with or without various membranous endothecal processes and complexity of spines. The sclerotized endothecal processes, and the phallotremal sclerites with variously developed or reduced membranous endothecal processes, possibly developed from this condition.