Podonychus gyobu, Yoshitomi & Hayashi, 2020

Yoshitomi, Hiroyuki & Hayashi, Masakazu, 2020, Unexpected discovery of a new Podonychus species in Kyushu, Japan (Coleoptera, Elmidae, Elminae, Macronychini), ZooKeys 933, pp. 107-123 : 107-108

publication ID	https://dx.doi.org/10.3897/zookeys.933.48771
publication LSID	lsid:zoobank.org:pub:AF5FAEDE-580A-470D-A2BC-299A9B163E2D
persistent identifier	https://treatment.plazi.org/id/3EDFF62A-25F7-4BEF-AA92-88FF2ED8B260
taxon LSID	lsid:zoobank.org:act:3EDFF62A-25F7-4BEF-AA92-88FF2ED8B260
treatment provided by	ZooKeys by Pensoft
scientific name	Podonychus gyobu
status	sp. nov.

Treatment

Podonychus gyobu sp. nov. Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 Japanese name: Hyotan-hime-doromushi View Figure 8

Type material.

Holotype (EUMJ): male, "JAPAN: KYUSYU/Oita Pref. Usa shi/Yamabukuro: Iroha-gawa", "[locality name in Japanese characters] 12. XII. 2018 33.498440, 131.28958 D. Inoue leg.". Paratypes (EUMJ, NMW, HOWP, KMNH), 1 ex., same data as for the holotype; 1 ex., same locality, but 8. XII. 2018; 2 males, 2 females, and 6 exs., same locality, but 15. XII. 2018, J. Nakajima, D. Inoue leg.; 6 exs., same locality, but 30. III. 2019, H. Yoshitomi leg.; 1 ex., "JAPAN: KYUSYU Oita Pref. Usa-shi [locality name in Japanese characters]", "[locality name in Japanese characters] 33.421472, 131.357887 24. XII. 2018, D. Inoue leg."; 3 exs., "Noyama, Ajimu machi, Usami-shi, Oita Pref., Kyushu, Japan, 33.412806, 131.349694, 29. XI. 2019 H. Yoshitomi leg."; 2 exs., "Yasaka-gawa, Yamaga-machi, Kitsuki-shi, Oita Pref., 33.430687, 131.477928, 24. I. 2020, D. Inoue leg.".

Larval specimens examined.

3 mature larvae (EUMJ in ethanol), Iroha-gawa, Yamabukuro, Usa shi, Oita Pref., 30. III. 2019, H. Yoshitomi leg.

Comparative specimen examined.

Podonychus sagittarius Jäch & Kodada, 1997: 1 male paratype (EUMJ), "INDONESIEN 1991 (22) Siberut, Toteburu-Bakeuluk leg. Jäch 17.2", "PARATYPUS Podonychus sagittarius sp. nov. des. Jäch & Kodada ‘98”.

Diagnosis.

The new species is morphologically similar to P. sagittarius , and differs from it in the following characteristics: 1) penis almost straight from base to near apex in lateral view (slightly curved ventrally in P. sagittarius ); 2) lateral margins of the 2nd labial palpomeres strongly arcuate (weakly arcuate in P. sagittarius ); 3) 3rd antennomeres longer than wide (as long as wide in P. sagittarius ). The endophallicstructures of P. sagittarius were not described in detail, but judging from the aedeagus illustrations ( Jäch and Kodada 1997, figs 78-80) they are similar to those of P. gyobu sp. nov.

Description of adult.

Body (Fig. 1A-D View Figure 1 ) obovate, convex dorsally, shiny. Coloration of body brown, mouth parts, antennae and legs paler. Plastron distributed in posterior part of head (Fig. 3B View Figure 3 ), elytral intervals VIII-IX (Fig. 2C-F View Figure 2 ), hypomera, epipleura, lateral part of meso- and metaventrites, and abdominal ventrites I-V (Fig. 2G, H View Figure 2 ).

Head with sparse suberect setae. Eyes small with about 40 facets. Antennae 6-segmented; approximate ratio of length of antennomeres 1-6: 6: 7: 6: 2: 3: 14 (N = 1, paratype). Maxillae (Fig. 4B View Figure 4 ) with oblong terminal segment of galea; maxillary palpi 3-segmented, with oblong terminal palpomere. Mandibles (Fig. 4C View Figure 4 ) feebly asymmetrical, with three apical teeth, shallowly notched in antero-lateral parts, bearing setae in lateral part. Labium (Figs 3C View Figure 3 , 4D View Figure 4 ) with 2-segmented palpi; terminal palpomeres strongly arcuate along lateral margins. Pronotum (Fig. 2B, C View Figure 2 ) with sparse suberect setae, widest at basal 1/3, depressed transversally in the middle; median groove (Fig. 2A View Figure 2 ) thin and shallow, running from posterior almost to anterior margin; sublateral carinae absent; lateral declivity (Fig. 2B View Figure 2 ) with oblique impressions; PW/PL 0.88-1.08 (1.03). Elytra with small tubercles along anterior margin, with one pair of sublateral carinae on interval VIII (Fig. 2E, F View Figure 2 ); plastron setae on intervals VIII-IX; EL/EW 1.47-1.63 (1.55); EL/PL 1.95-2.32 (2.18); EW/PW 1.28-1.50 (1.37); TL/EW 2.13-2.37 (2.26). Hind wings (Fig. 3A View Figure 3 ) reduced, examined specimen (paratype) micropterous. Legs relatively long; length of foreleg about 0.9 times as long as TL. Ventral side of thorax and abdomen more or less as in P. sagittarius .

Male. Tergite VIII (Fig. 4E View Figure 4 ) semicircular, bearing long setae in caudal part; sternite VIII (Fig. 4F View Figure 4 ) semicircular, with slender and relatively long median strut; sternite IX (Fig. 4G View Figure 4 ) slightly sclerotized, oblong, with long and slender paraproct. Aedeagus (Fig. 4H-J View Figure 4 ) long, almost straight; phallobase short, slightly less than 0.25 times as long as penis (LB/ML), with semicircular sclerotization projecting dorsally; parameres absent; penis long, almost straight, with pointed apex curved ventrally; fibula and corona absent; C 160o; MH/ML 0.16; BL/CL 0.60; LCP/LBP 1.59. Endophallus in everted condition (Fig. 3D-H View Figure 3 ) longer than penis, lacking bladders and distinct sclerites; basal tube (BT in Fig. 3D View Figure 3 ) long, 350 μm, bearing scaly spines; apical tube (AT in Fig. 3D View Figure 3 ) 250 μm, projecting from ventro-apical part of BT, well sclerotized and slender in basal 2/3, expanded and membranous in apical 1/3 closely covered with shallow furrows; gonopore situated at apex of AT.

Female. Tergite VIII (Fig. 4K View Figure 4 ) semicircular, bearing setae of variable length; sternite VIII (Fig. 4L View Figure 4 ) shallowly concave in caudal margin, bearing long setae in postero-lateral parts, with long and stout median strut. Ovipositor (Fig. 4M View Figure 4 ) longer than sternite VIII, bearing minute apical sensilla on stylus and coxite; approximate ratio of stylus, distal part of coxite, basal part of coxite and valvifer (N = 1) as 1.0: 4.3: 2.6: 8.0. Secondary sexual dimorphism not strongly pronounced.

Measurement (N = 10). TL 1.21-1.36 (1.28) mm; PW 0.37-0.45 (0.41) mm; PL 0.37-0.43 (0.40) mm; EL 0.82-0.95 (0.87) mm; EW 0.51-0.60 (0.56) mm.

Description of larva.

Body (Fig. 5A-C View Figure 5 ) semi-cylindrical in cross-section, convex dorsally, flat ventrally. Coloration of body entirely pale orange; legs paler; granules on dorsum darker, forming longitudinal stripes.

Head visible dorsally, well exposed from prothorax, trapezoidal, widest at apical 1/3, densely covered with short spines, bearing short setae. Eyes (Fig. 6C, E View Figure 6 ) lacking lens of stemmata. Antennae (Figs 5D View Figure 5 , 6F View Figure 6 ) relatively long; antennomere Ias long as wide; antennomere II long, with long and slender sensorial appendage; antennomere III shorter than sensorial appendage on antennomere II, with short sensorial appendage at apex. Labrum (Fig. 5E View Figure 5 ) transverse, with a row of pectinate setae in anterior part of dorsal surface, with a pair of long apodemes projecting from postero-lateral corners. Mandibles (Fig. 5F View Figure 5 ) subtriangular, with long and pectinate setae on lateral parts; two apical teeth short and blunt; basal setose processes long. Maxillae (Figs 5G View Figure 5 , 6D View Figure 6 ) with relatively long palpi. Labium (Figs 5G View Figure 5 , 6D View Figure 6 ) with a pair of long setae in middle. Thorax serrate in lateral parts, widest at metathorax. Prothorax with seven ventral sclerites; mesal one small, situated between procoxae; antero-lateral ones wide, bearing plumose setae on anterior margin; postero-lateral ones quadrate, bearing three long plumose setae. Mesothorax with five ventral sclerites; mesal one wide and transverse, sinuate at posterior margin, bearing short bipectinate setae near midcoxae; antero-lateral ones oblong, bearing long bipectinate setae. Metathorax with five ventral sclerites; mesal one wide and transverse, bearing short setae. Granules on dorsal surface of thorax and abdomen (Fig. 7D, E View Figure 7 ) distributed linearly and somewhat irregularly, bearing short setae in posterior end, with long and curved setae in basal part. Y-shaped projections (Fig. 7A, D, F View Figure 7 ) present on caudal margins of thoracic and abdominal segments. Spiracles thumb-shaped, on mesothorax and abdominal segments I-VIII, situated near lateral margin. Legs 5-segmented, short and stout; apical segment stout, with short inner seta. Abdomen (Fig. 8C View Figure 8 ) with pleural sclerites on segments I-VII, gently tapering caudally. Abdominal segment IX (Fig. 8G View Figure 8 ) long, as long as abdominal segments VI-VIII combined, flat ventrally, serrate at apex (Fig. 8E View Figure 8 ), with line of granules in midline of dorsal surface, bearing four long lateral setae and one ventral seta, densely covered with short spines. Ventral operculum (Fig. 8G, H View Figure 8 ) oblong, situated in caudal 1/3 of abdominal segment IX.

Biological notes.

This species lives in small rivers at low elevation. Larvae and adults were collected from submerged roots of reeds using a net. They were collected with Elmomorphus brevicornis Sharp, 1888 and Stenelmis nipponica Nomura, 1958.

Distribution.

So far, this species is known only in the Iroha and Yakkan river systems, in the eastern part of Kyushu, Japan.

Etymology.

“Gyobu” is an NPO (nonprofit organization) in Kitakyushu, Fukuoka. This new species was discovered during a survey of water beetle fauna by Mr D. Inoue, president of "NPO Kitakyushu Gyobu". The epithet is a noun in apposition.