Psilotreta spatulata, Kawase, 2022

Kawase, Naoki, 2022, The genus Psilotreta Banks (Trichoptera, Odontoceridae) in Japan, Zootaxa 5195 (6), pp. 501-521 : 507-510

publication ID	https://doi.org/ 10.11646/zootaxa.5195.6.1
publication LSID	lsid:zoobank.org:pub:1A42B1B9-9D3F-44D8-B9C7-0D96CB2312ED
DOI	https://doi.org/10.5281/zenodo.7231569
persistent identifier	https://treatment.plazi.org/id/E84587ED-FFA4-0871-E7BC-FA6C62C0FDFA
treatment provided by	Plazi
scientific name	Psilotreta spatulata
status	sp. nov.

Treatment

Psilotreta spatulata sp. nov.

( Figs 3A–3M View FIGURE 3 , 9F, 9I View FIGURE 9 , 11C View FIGURE 11 )

Psilotreta sp. Tsuda 1938 , 104, larva, case, Okinawa Island; Tanida 2003, 374, 380, case, Okinawa Island.

Diagnosis. The male genitalia of P. spatulata sp. nov. are most similar to those of P. moritai in the shapes of a pair of flattened spatula-shaped lateral processes but can be distinguished from the latter by the following structures: (1) the shape of each lateral process of tergum X is sub-triangular in lateral view in P. spatulata sp. nov. ( Figs 3I1–3I View FIGURE 3 View FIGURE 1 View FIGURE 2 4 View FIGURE 4 ), but narrow rectangular in P. moritai ( Figs 4C View FIGURE 4 1 View FIGURE 1 , 4C View FIGURE 4 2 View FIGURE 2 ); and (2) a pair of parameres in the phallus are long and located laterally in P. spatulata sp. nov. ( Figs 3J, 3K View FIGURE 3 ), but they are short and located ventrally in P. moritai ( Figs 4D, 4E View FIGURE 4 ).

Adult ( Figs 3A–3C View FIGURE 3 ). Body and antennae brown, wings light brown in alcohol. Length of each forewing: male 8.2–9.3 mm (mean = 8.7, n = 10), female 8.2–9.9 mm (mean = 9.3, n = 7). On head dorsally, eyes hemispherical, large especially in male ( Fig. 3A View FIGURE 3 ); locations and shapes of setal warts most similar to those of P. japonica ( Fig. 1A View FIGURE 1 ), but pair of anterior warts round oval (narrow transverse in P. japonica ). Venation similar to that of P. japonica ( Figs 1B, 1C View FIGURE 1 ), but crossvein m-cu absent in male hind wings ( Fig. 3B View FIGURE 3 ), and base of M3+4 and Cu1a directly connected without cross vein in female forewings ( Fig. 3C View FIGURE 3 ).

Male genitalia ( Figs 3D–3K View FIGURE 3 ). Tergum IX elongate, subtriangular in dorsal view, with steep sides above basal setal warts ( Figs 3D, 3E, 3H View FIGURE 3 ). Basal segment of each inferior appendage as long as preanal appendages, thick, slightly dilated at middle in lateral view, covered with setae; apical segment about 1/2 as long as basal segment, cylindrical with many small brown teeth on apical half ( Figs 3D, 3G, 3H View FIGURE 3 ). Preanal appendages elongate, compressed ( Fig. 3D View FIGURE 3 ). Median dorsal process of tergum X extending posteriorly, apical half clavate with truncate or round apex in dorsal view ( Figs 3D–3F View FIGURE 3 2 View FIGURE 2 ). Pair of lateral processes of tergum X sclerotized, as long as median dorsal process, forming subtriangular plate in lateral view ( Fig. 3H View FIGURE 3 ); each with ventral projection extending antero-ventrad ( Figs 3I1–3I View FIGURE 3 View FIGURE 1 View FIGURE 2 4 View FIGURE 4 ); posterior portion of each lateral process occasionally bearing few denticles ventrally (marked with arrows in Figs 3I View FIGURE 3 1 View FIGURE 1 , 3I View FIGURE 3 2 View FIGURE 2 ), dorsal margins of lateral processes sometimes partially concave beside their intermediate appendages (marked with arrows in Figs 3E, 3I View FIGURE 3 4 View FIGURE 4 ). Pair of intermediate appendages dark brown, heavily sclerotized, and strongly curved, C-shaped in lateral view, with acute apex directed posterad ( Figs 3D, 3H, 3I1–3I3 View FIGURE 3 View FIGURE 1 View FIGURE 2 ), sometimes directed posterolaterad ( Figs 3E, 3I View FIGURE 3 4 View FIGURE 4 ).

Phallus with phallotheca long, cylindrical; endotheca with pair of long, acute parameres laterally, each apex directed posterolaterad; aedeagus membranous with weakly sclerotized ventral plate, phallotremal sclerite V-shaped in ventral view, strongly curved dorsad ( Figs 3J, 3K View FIGURE 3 ).

Female genitalia ( Figs 3L–3M View FIGURE 3 ). Sternum IX semicircular to sub-triangular in ventral view with median longitudinal sulcus at posterior 2/3 of sternum IX between pair of indefinite broad pigmentations ( Fig. 3M View FIGURE 3 ). Posterior margin of segment X transverse, almost straight in ventral view; segment X with pair of flattened (depressed) dorsolateral lobes, sparsely setose ( Fig. 3L View FIGURE 3 ). Length of vaginal apparatus 2 times as long as sternum IX.

Final instar larva ( Figs 9F, 9I View FIGURE 9 ). Length up to 9 mm. Generally similar to those of P. japonica and P. kisoensis , but head and thoracic nota uniformly brown to dark brown without markings. Among primary setae on head, setae 9, 12, 14, and 15 thick, pale brown, other setae fine, white to near transparent; setae 14 longest and 1.5 to 2 times as long as 9; setae 9 second longest and about 1.5 to 2 times as long as 15. Branched gills as in Fig. 9I View FIGURE 9 on each side of abdomen (numbers of branches in parenthesis, n = 3): anterior dorsal gills on segments II (8–10), III (8–14), IV (10), V (7–8), VI (4–7), VII (3–5) and VIII (0-4); anterior ventral gills on segments II (8), III (10–14), IV (8–12), V (8–11), VI (6–7), VII (4–7) and VIII (2–4); anterior lateral gills lacking. Case similar to that of P. japonica , but smaller.

Holotype. Male (in alcohol), Okinawa Island. Okuni-rindo, Iji, Kunigami-son , Okinawa Pref., 26°44'03" N 128°13'36"E, 21.iii.1999, T. Ito and A. Ohkawa ( LBM1410012539 View Materials ). GoogleMaps

Paratypes. Okinawa Island : 9 males, 1 female, same data as holotype ( LBM1410012540 View Materials – LBM1410012549 View Materials ) GoogleMaps ; 1 male, Sukuna-gawa, Yona, Kunigami-son , 26°45'N 128°13'E, 22.iii.1999, T. Ito and A. Ohkawa ( LBM1410012550 View Materials ) GoogleMaps ; 4 males, same locality, 10.iv.2011, T. Ito ( LBM1410012551 View Materials – LBM1410012554 View Materials ) GoogleMaps ; 9 males, 4 females, Genka, Nago-shi , 26°36'N 128°04'E, 8.iv.2011, T. Ito ( LBM1410012555 View Materials – LBM1410012567 View Materials ) GoogleMaps ; 1 male, 5 females, Benoki, Kunigami-son , 26°8'N 128°3'E, 9.iv.1996, M. Aoyagi ( OMNH) GoogleMaps ; 2 males, Hiji river, Kunigami-son , 26°7' N 128°2' E, 12.iv.1996, M. Aoyagi ( OMNH) GoogleMaps ; 2 males, 1 female, Ryukyu University Station, Yona, Kunigami-son , 26°76'N 128°21'E, 11.iv.1996, M. Aoyagi ( OMNH) .

Other specimens examined. Okinawa Island: 1 male, 2 females, Genka, Nago-shi , 26°36'N 128°04'E, 8.iv.2011, T GoogleMaps . Ito ; 3 males, same locality, 18.iii.2012, T . Ito ; 2 males, 2 females, Hogen-hashi, Genka, Nago-shi , 8.iv.2011, T . Ito ; 3 larvae, same locality, 22–24.xi.2010, T . Ito ; 6 larvae, same locality, 17–19.x.2014, T . Ito ; 1 female, Heigi-hashi, Genka, Nago-shi , 26°45'N 128°13'E, 18.iii.2012, T GoogleMaps . Ito ; 1 larva, Teina-gawa, Nago-shi , 26°56'N 128°09'E, 10.i.1989, T GoogleMaps . Kishimoto ( OMNH) ; 1 male, 1 female, Benoki, Kunigami-son , 26°8'N 128°3'E, 12.iv.1997, M. Yoshio GoogleMaps ; 9 males, same locality, 12.iv.1997, T GoogleMaps . Ueda ; 1 female, Ie-rindo, Sosu, Kunigami-son , 11–15.iv.2001, K. Uesugi ; 1 male, Hiji, Kunigami-son , 26°42' N 128°11' E, 27.iii.2006, K. Konishi GoogleMaps ; 8 males, 2 females, same locality, 8.iv.2011, T GoogleMaps . Ito ; 1 male, 1 female, same locality, 10.iv.2011, T . Ito ; 1 larva, same locality, 21.iii.1999, T . Ito and A. Ohkawa ; 1 male, Ryukyu University Station, Yona, Kunigami-son , 26°76'N 128°21'E, 2.iv.1986, N. Kobayashi ( OMNH) ; 1 male, same locality, 8.iv.1996, M. Aoyagi ; 2 larvae, Aha, Kunigami-son , 26°70'N 128°28'E, 16.x.1988, S. Shokita ( OMNH) ; 2 larvae, 4 cases, same locality, 5.ix.1994, M. Aoyagi ( OMNH) ; 1 male, Takasato, Ogimison , 26°41'N, 128°11'E, 17.iii.2012, T GoogleMaps . Ito ; 1 larva and 2 pupae, Okukubi, Kin-cho , 26°28'20”N 127°55'35”E, 22.vi.2004 GoogleMaps ; 3 males, 1 female, Okukubi, Kin-cho , 26°29'N 127°55'E, 1.iii.2011, R GoogleMaps . Kuranishi. Ishigaki Island : 1 male, Omoto-dake, Ishigaki-shi , 18–19.iii.2002, I. Oshima, K. Sugishima and T . Yoshida .

Etymology. The Latin species epithet spatulata is derived from the spatula-shaped lateral processes in the male genitalia.

Distribution and habitat. Psilotreta spatulata sp. nov. is an Oriental species distributed in Okinawa and Ishigaki Islands in the Ryukyu Archipelago, southwestern Japan ( Fig. 11C View FIGURE 11 ) and was found in small mountainous streams.

Remarks. Tsuda (1938) recorded larvae and pupae of unidentified Psilotreta species from Okinawa Island and Tanida (1997) also recorded unidentified larvae and males from Okinawa Island. These larvae do not have distinct markings on their heads and thoracic nota as found in previously known Japanese species, P. japonica and P. kisoensis ( Tsuda 1938, Tanida 2003). The author examined the male and larval specimens deposited in Osaka Museum of Natural History that were used by Tanida (1997) and confirmed that both the adults and larvae agree with those of P. spatulata sp. nov. described above. Although the author could not examine specimens used by Tsuda (1938), they most probably belong to this species.

Japanese name. Okinawa-kiso-tobikera.