Three new species of Metalype from China, Metalype hubeiensis Qiu & Morse, sp. n., M. shexianensis Qiu & Morse, sp. n., and M. truncata Qiu & Morse, sp. n., are described and illustrated. Metalype uncatissima (Botosaneanu, 1970) is reported from China for the first time. The differences between genus Metalype and genus Psychomyia are discussed and four Psychomyia species are transferred to Metalype: Metalype holzenthali (Schmid, 1997); M. klapaleki (Malicky, 1995a); M. kumari (Schmid, 1997); and M. nithaiah (Malicky, 2014). A key to the males of Metalype species of the world is provided.

Annulipalpia , caddisfly, east Palearctic Region, Oriental Region

Knowledge of the Chinese Trichoptera fauna was limited before the mid-1900s, described solely by foreign scholars (Morse et al. 1994). It has increased considerably since the 1980s, mostly due to the work of Chinese scientists. There were only 530 Chinese species known by 1990 (Yang et al. 2005), but 1267 Chinese species were described by the middle of 2014 (Yang et al. 2016). However, records of Psychomyiidae increased from 19 species to only 26 species in that interval; this number is relatively small compared to the number of Psychomyiidae species known from the Oriental and East Palearctic Regions (405 spp., Morse unpublished data) and from adjacent countries (e.g., 73 spp. in India, 58 in Thailand, 35 in Vietnam; Morse unpublished data). Schmid (1984) estimated that there are actually 40,000 caddisfly species in southwestern Asia, although this estimate has been questioned by Malicky (1993a). Thus, this study is part of a continuing effort to document the Chinese caddisfly fauna that is mostly unknown to science, focusing here on Metalype of Psychomyiidae.

The genus Metalype was established by Klapálek (1898). For more than 100 years, it contained only the type species Metalype fragilis (Pictet, 1834). Wing venation (Fig. 1) and male genitalia of Metalype are very similar to those of Psychomyia Latreille, 1829 (in Cuvier 1829; type species Psychomyia annulicornis Pictet, 1834, selected by Ross 1944, synonym of Psychomyia pusilla Fabricius, 1781). Malicky (1995a) suggested that Metalype is a synonym of Psychomyia. Schmid (1997) treated M. fragilis as a Psychomyia species and included it in his Psychomyia mahayinna species group (“Mahayinna Group”) with six other Psychomyia species; he suggested that this group is the oldest lineage of Psychomyia. Li and Morse (1997) completed a phylogenetic analysis of Psychomyiidae and concluded that Metalype is a monophyletic genus closely related to Psychomyia and Paduniella Ulmer, 1913 (type species Paduniella semarangensis Ulmer, 1913, monotypic), these three genera collectively constituting the subfamily Psychomyiinae. Li and Morse (1997) also listed characters supporting the monophyly of Metalype and transferred three Psychomyia species to Metalype. Later, they indicated that Metalype and Psychomyia are sister genera, and Metalype + Psychomyia is the sister lineage to Paduniella (Li and Morse 1998). However, some Metalype species are still considered to belong in Psychomyia by some authors (Robert 2002, Mey and Nozaki 2006, Waringer and Graf 2011, Malicky 2014). Frandsen et al. (2016) concluded that Psychomyiinae is monophyletic, but in addition, they included the genus Lype McLachlan, 1878 (type species Lype phaeopa (Stephens, 1836), selected by Ross 1944) as sister to Paduniella in their phylogeny of this subfamily.

Figure 1. 

Wing venation of Metalype truncata sp. n., right wings, dorsal. A forewing B hind wing.

In Asia, Metalype species have been reported from Japan (Mey and Nozaki 2006, Nozaki and Nakamura 2007), Korea (Botosaneanu 1970), Nepal (Malicky 1995b), Pakistan (Schmid 1961), and Russia (Levanidova et al. 1995), but not from China (Yang et al. 2016); this apparent absence may have resulted from a lack of studies, or Metalype species are recognized in China as species of Psychomyia. For example, Psychomyia nithaiah Malicky, 2014 was described from Taiwan, but it is probably a Metalype species because it is very similar to Metalype uncatissima (Botosaneanu, 1970). In this article, we report four Metalype species from China, with three of them new to science. We also discuss the differences between Metalype and Psychomyia species. A key to males of Metalype species of the world is also provided.

The three new species were first described in Dr Li You-wen’s dissertation (Li 1998), but their names were explicitly excluded from availability under Article 8 of the 3^rd edition of the International Code of Zoological Nomenclature (International Commission on Zoological Nomenclature 1985). However, Dr Li deposited his material in the Clemson University Arthropod Collection (CUAC), Clemson, South Carolina, USA; and Department of Plant Protection, Nan-jing Agriculture University (NJAU), Nan-jing, People’s Republic of China (PRC). Here these species are described based on those specimens to make the names available.

Specimens were collected with ultraviolet light traps during 1990–1993 and were preserved in 80% ethanol. The sampling sites are listed in Table 1, with original label names and modern or corrected Chinese names. Holotypes of the new species are deposited in NJAU, paratypes are deposited in NJAU and CUAC. The specimens of Psychomyia klapaleki Malicky, 1995a and Metalype fragilis were loaned by Dr Hans Malicky from his personal collection in Lunz am See, Austria.

Specimens are all preserved in 75%–100% ethanol. Abdomens of a few individuals were removed and water-bath heated in 10% KOH for a few minutes to remove muscle and other non-chitinous tissues for illustration. Specimens were observed under a dissecting microscope. An eyepiece with a grid was used to prepare pencil templates of the various views. The templates were traced with the vector graphics software Adobe Illustrator® (version 19.0.0, 64-bit).

For the specimens that were collected during 1990–1993, no geographical coordinates were taken by GPS at that time. We tried to find the most probable sampling sites based on the location names and descriptions of original labels, and obtained the geographical coordinates from Google Earth (Version 7.1.7.2600). The elevation of one site: An-hui Province, She County, Yan-yuan Town, Huang-bai-shan Village, was missing, so the elevation of this site was also obtained from Google Earth. Elevations of all other sites were obtained from the labels. Modern Chinese names and geographical coordinates of sampling sites were confirmed by Prof Sun Chang-hai (Sun C-h) of Nan-jing Agriculture University.

Terminology for wing venation (Fig. 1) follows that of Schmid (1998). Terminology for male genitalia follows Nielson (1957) except that the pair of flat processes beyond the superior appendages are called “Tergites IX+X” (Ross 1938) and the apical portion of the phallus is called a “phallicata” (“phalicata” [sic], Ross 1956). Terminology for larvae follows Wiggins (1996).

To date, only the characters of the type species, Metalype fragilis, have been used to diagnose the genus Metalype. Among the diagnostic characters now known to distinguish Metalype and Paduniella, synapomorphic characters for Metalype include the apicomesal spurs of the hind tibiae that are short and curved, twisted, truncate or forked apically; in the male genitalia the subapicomesal teeth of the superior appendages and the contorted phallus without a paramere. Synapomorphic characters for Paduniella include the 6-segmented maxillary palps, 4-segmented labial palps, and compressed male harpagones (Li and Morse 1997).

According to Li and Morse (1997, 1998), the most obvious differences between males of Metalype and Psychomyia are (1) The presence or absence of subapicomesal teeth on the superior appendages; (2) the size of the mesodorsal expansion of the basal half of each harpago; (3) the presence or absence of membranous basodorsal surfaces of the harpagones; and (4) the degree of fusion of male tergites XI+X with the superior appendages. These and other characters and their polarities are indicated in Table 2.

The presence or absence of subapicomesal teeth on the superior appendages is easily recognized. However, similar teeth are found in Psychomyia amor Malicky & Chantaramongkol, 1997; P. amphiaraos Malicky & Chantaramongkol, 1997; P. andromache Malicky, 1997; P. andromeda Malicky, 1997; P. asvagosha Schmid, 1961; P. capillata Ulmer, 1910; P. dasaratha Malicky, 1993b; P. holzenthali Schmid, 1997; P. kalais Malicky, 2004b; P. kiskinda Malicky & Chantaramongkol, 1993; P. klapaleki, P. kumari Schmid, 1997; P. kuni Malicky & Chantaramongkol, 1993; P. lak Malicky & Chantaramongkol, 1993; P. monto Malicky & Chantaramongkol, 1993; P. neboissi Schmid, 1997; P. nithaiah, P. sinon Malicky & Prommi, 2006; P. sonlana Oláh & Malicky, 2010; P. vietnama Oláh & Malicky, 2010; and P. wigginsi Schmid, 1997; Among them, P. nithaiah, P. holzenthali, P. kumari, and P. klapaleki are very similar to the three species transferred to Metalype by Li and Morse (1997): M. anaktujuh, M. mahayinna (Schmid, 1961), and M. uncatissima. The latter three species were included in Schmid’s Psychomyia mahayinna group together with Metalype fragilis (Schmid, 1997), so we hypothesize that these four species also belong to the genus Metalype and we cite them in Metalype through the remainder of this paper. All of the other 17 species above with subapicomesal teeth on the superior appendages are very different from Metalype by the following characters: (1) Tergites IX+X are fused with the superior appendages completely (synapomorphy; tergites IX+X are separated from the superior appendages in Metalype); (2) the superior appendages are greatly expanded basodorsally (synapomorphy; the superior appendages are not expanded in Metalype); (3) the superior appendages each have a large mesal concavity (synapomorphy; the superior appendages are without concavities in Metalype); (4) the coxopodites are semicircular (semicircular condition is synapomorphic; the coxopodites are round, triangular, or rectangular in Metalype); (5) the harpagones are forked (synapomorphy; the harpagones are single in Metalype).

The phallicata is more or less vertical basally and has a reversed-S-shape with an apical hook directed dorsad in Metalype species and all of these 17 Psychomyia species. This general shape is a synapomorphy for Psychomyia and Metalype, with the phallicata of Psychomyia species other than those 17 species generally more nearly horizontal and evenly curved, probably apomorphic within Psychomyia.

Moreover, P. sonlana, P. sinon and P. andromache also have a few more mesal spines on the superior appendages. Considering that there are many Psychomyia species with dense spines on the mesal surfaces of the superior appendages, it is possible that the subapicomesal teeth in these species are remnants or a modification of the mesal spines in one or more monophyletic groups within genus Psychomyia and thus these spines are a homoplasy, not homologous with the synapomorphic subapicomesal teeth of Metalype.

The peculiar shape of the expansion of the harpagones is not observed in Psychomyia species. It is not apparent also in Metalype shexianensis and M. anaktujuh. Instead, these two species have a mesal process on each of harpago, possibly representing a dorsal hump that shifted apicomesad. Metalype holzenthali, M. klapaleki, and M. nithaiah have that kind of expansion; whereas M. kumari has mesal processes that resemble those of M. shexianensis and M. anaktujuh. This expansion, possibly modified into a mesal process in some species, is likely a synapomorphy for some, if not all species of Metalype.

The membranous basodorsal surfaces of the harpagones are present in all Metalype specimens we observed, but this character is seldom mentioned in descriptions. Botosaneanu (1970) described this character in the original description of Metalype uncatissima. Malicky (1995a) mentioned this character in his re-description of M. fragilis and his description of M. klapaleki. Under the dissecting microscope, the membranous part is often without setae, the color is white or light yellow, the boundary between the membranous and the non-membranous parts is very obvious; after clearing, the membranous part is transparent and almost invisible, so that it can be distinguished from other parts. This character is likely a synapomorphy for Metalype.

Schmid (1997) described the separation of tergites IX+X and superior appendages as a character of his Psychomyia mahayinna group. This separation can be recognized in all Metalype species and the fusion of these structures is seen in most Psychomyia species. However, the fusion of tergites IX+X with the superior appendages is not very obvious in some Psychomyia species, for example Psychomyia arefinae Schmid, 1997; P. schefterae Schmid, 1997 and P. scottae Schmid, 1997. On the other hand, the bases of the superior appendages can be very wide (Metalype anaktujuh, M. shexianensis), which can make this character ambiguous. Metalype holzenthali, M. klapaleki, M. kumari, and M. nithaiah all have tergites IX+X separated from the superior appendages, as for other Metalype species. Thus the fusion of tergites IX+X and superior appendages seems to be a synapomorphy within genus Psychomyia.

The apicomesal spurs of hind tibiae on Psychomyiidae species other than those of Metalype are straight and acute. On all Metalype species we have studied, the apicomesal spurs are shorter than the apicolateral spurs, and these apicomesal spurs are more or less curved, twisted, truncate, or forked apically (Figs 2E, 3F, 4E, 5E, 6). All Psychomyia specimens we observed (including Psychomyia flavida Hagen, 1861; P. extensa Li, Sun, and Yang, 1999; P. nomada (Ross, 1938), and eleven unpublished species from China) have apicomesal spurs straight and slightly longer than the apicolateral spurs, never forked or truncate. Metalype mahayinna has apicomesal spurs similar to those of Metalype truncata (Malicky 1996; pers. comm). Males of M. nithaiah and M. klapaleki (Fig. 7) also have the apicomesal spur on each hind tibia shorter than the apicolateral spur and curved apically, supporting the hypothesis that these species belong in Metalype. The spurs of M. holzenthali and M. kumari are unknown to us. The slightly curved, twisted, forked or truncate apicomesal spurs on male hind tibiae is a synapomorphy within genus Metalype.

Figure 6. 

Male of Metalype fragilis (Pictet, 1834). Apical spurs of right hind leg, ventral.

Figure 7. 

Male of Metalype klapaleki (Malicky, 1995a). Apical spurs of right hind leg, ventral.

A difference between Metalype and Psychomyia females is that those of Metalype have a transverse row of setae on segment IX and those of Psychomyia species are without these setae (presence of the transverse setal row is synapomorphic). This difference is observed in females of Psychomyia usuguronis (Matsumura, 1931) (Ito et al. 2011), P. flavida (Ito et al. 2000), P. pusilla (Malicky 2004a), M. fragilis (Malicky 2004a), and M. uncatissima (Li and Morse 1997). However, the females are unknown for the four Psychomyia species we hypothesize here to belong to Metalype (M. nithaiah, M. holzenthali, M. kumari, and M. klapaleki).

Edington and Hildrew (1995) compared the larvae of Psychomyia pusilla and Metalype fragilis, and found three differences between them: (1) Psychomyia pusilla has the submental sclerites longer than wide, with dark patterns (synapomorphy); M. fragilis has the sclerites wider than long and without patterns. (2) Psychomyia pusilla has the ventral apotome small and triangular, no more than two times as wide as long (synapomorphy); M. fragilis has the ventral apotome expanded laterally, more than five times as wide as long. (3) Psychomyia pusilla has five or six teeth on the mesal surface of each anal claw; M. fragilis has two or three teeth (character polarity uncertain).

The long submental sclerite character is found in Psychomyia flavida and has been used for distinguishing the larvae of Psychomyia and Paduniella, with these sclerites wider than long in the latter (Wiggins 1996, Li and Morse 1997, 1998, Morse and Holzenthal 2008). We observed this long submental sclerite character for P. nomada specimens in the CUAC. On the other hand, the wide submental sclerites on larvae of Metalype species have been confirmed for the larvae of M. fragilis and M. uncatissimaby many authors (Waringer and Graf 2011, Urbanič et al. 2003, Coppa et al. 2009, Torii 2011, Torii and Nakamura 2016). For all the species mentioned above, the small ventral apotome is usually coupled with the longer submental sclerites. One exception is the Psychomyia sp. larva from Aichi (Torii and Nakamura 2016); that larva has submental sclerites longer than their width, but the ventral apotome is wide. Dark patterns on the submental sclerites of Psychomyia are always present, although sometimes faint.

Coppa et al. (2009) concluded that the main character distinguishing the larva of Paduniella vandeli Decamps, 1965 from that of Metalype fragilis is the number of teeth on the ventral margin of each anal claw. The final instar larva of P. vandeli bears seven or eight teeth on each anal claw (Coppa et al. 2009) while that of M. fragilis bears only two or three teeth (Coppa et al. 2009, Edington and Hildrew 1995). On the other hand, the larva of M. uncatissima has eight teeth on each anal claw (Torii 2011), Paduniella nearctica Flint, 1967 has four to six teeth; Psychomyia flavida (Morse and Holzenthal 2008) and Psychomyia sp. (probably P. lumina, Wiggins 1996) each have four teeth, and P. nomada has three or four teeth. The third instar larva of P. vandeli also has three teeth on each anal claw (Coppa et al. 2009). Moreover, the teeth may not be uniform; some of them can be very small and hard to recognize. Thus, the number of teeth on each anal claw is not a reliable character for distinguishing the three genera.

Torii and Nakamura (2016) identified larvae of Psychomyiidae by molecular methods. They compared the morphological characters of larvae and noted that the episternum of each foreleg of Metalype uncatissima is without a vertical suture while larvae of Paduniella horaiensis Nishimoto, 2011 and Psychomyia sp. have the suture. We observed this suture on P. nomada specimens, but it is also present on the larva of M. fragilis (Coppa et al. 2009), so that the absence of the suture may be an autapomorphy of M. uncatissima. Torii and Nakamura (2016) also mentioned that the mature larva of Metalype (5–6 mm) is longer than the larva of Paduniella (3–4 mm). The phylogenetic evidence and diagnostic differences for larvae of Metalype and Paduniella remain inconclusive until more information on larvae is available.

The larva of M. klapaleki has submental sclerites wider than long. In fact, no differences have been found between larvae of M. klapaleki and larvae of M. fragilis (Urbanič et al. 2003), further supporting our hypothesis that M. klapaleki is a species of Metalype. Larvae are unknown for the other three species that we transfer here to Metalype. When they become known, we predict that the larval characters for those species will support our hypothesis.

The male genitalia of Metalype and Psychomyia are very similar to each other, but there are some distinctive characters supporting the monophyly of each genus. The details are shown in Table 2. The known female genitalia and larvae of Metalype are similar to those of Paduniella and both of them are very different from female genitalia and larvae of Psychomyia. Treating Metalype as a synonym of Psychomyia may cause difficulties for identifying females and larvae of Psychomyia. However, female genitalia and larvae of only a few species are known in these genera, such that more information will be helpful. Based on the characters of males, we conclude that the following species should be transferred from Psychomyia to Metalype:

Metalype holzenthali (Schmid, 1997), comb. n.

Metalype klapaleki (Malicky, 1995a), comb. n.

Metalype kumari (Schmid, 1997), comb. n.

Metalype nithaiah (Malicky, 2014), comb. n.

The dissertation research of Dr Li You-wen formed the template and inspiration for this publication. By his choice, we were unable to communicate with Dr Li to assure his agreement to publish the work, necessitating our publishing it without his explicit authorship. Even so, we are very thankful for his significant scientific contributions to it. We are grateful to our colleagues in Nan-jing Agriculture University for lending specimens. Thanks to Prof Sun C-h for his help on confirming the information about sampling sites. Thanks to Dr H Malicky for loaning specimens. Thanks to Dr P Frandsen for providing molecular data for reference. Thanks to all the colleagues mentioned in the text for assistance to collect the specimens. We also appreciate the reviewers’ and the editor’s suggestions that helped us to get this manuscript published.