Pseudovelia lasiomma Watanabe et Hayashi, sp. nov.

[Japanese name: Biwako-Nagare-Katabiroamenbo]

(Figs. 1–10, 12–24)

Pseudovelia sp.: Hayashi et al. 2023: 4.

Type Material. HOLOTYPE: apterous male (EUMJ), Lake Biwa, Kitoge, Imadu-cho, Takashima-shi, Shiga Prefecture, Japan, 3 XI 2022, K. Watanabe leg. PARATYPES: 83 apterous males, 82 apterous females (EUMJ, HOWP, IIM, KWC), same data as holotype; 1 apterous male, 1 apterous female (KWC), Lake Biwa, Asahi, Shinasahi-cho, Takashima-shi, Shiga Prefecture, Japan, 4 VII 2017, K. Watanabe leg. ; 1 apterous male, 2 apterous females (KWC), Lake Biwa, Kitafunaki, Adogawa-cho, Takashima-shi, Shiga Prefecture, Japan, 19 VII 2018, K. Watanabe leg. ; 2 apterous males, 1 apterous female (HOWP) LC738991 – LC738993, Lake Biwa, Otsu-shi, Shiga Prefecture, Japan, 12 II 2022, Y. Ishiyama leg.

DNA barcodes. The 658 bp COI gene sequence data are available. The accession numbers (LC738991 – LC738993) have been registered in the DNA Data Bank of Japan (Hayashi et al. 2023).

Description.

Apterous male (Figs. 1–2, 5, 7, 12–24). Coloration (Figs. 1, 5, 7): Head blackish-brown, median line of head grey, posterior margin brown; labrum yellowish-brown, rostrum dark-orange, segment 3 middle to segment 4 apex black; antennal segment I yellowish-brown, apical part dark-brown, segment II dark-brown, basal part yellowishbrown, segments III–IV dark-brown; inner margin along eyes silver; eyes dark-red; pronotum dark-brown, anterior portion brown, punctation black; mesopleuron and metapleuron blackish-brown; fore leg mainly yellow, apex of femur dark-brown, base and apex of tibia dark-brown, apical half of tarsus dark-brown; middle leg mainly yellow, apex of femur and tarsomere I dark-brown, tibia mainly dark-brown, apical half of tarsomere II dark-brown; hind leg mainly yellow, base and apex of tibia dark-brown, apex of tarsomere I–II dark-brown; abdomen mainly brown, lateral portions of mediotergite I, posterior margin of mediotergite VI, mediotergite VII, and mesal margins of laterotergites III–V with prominent silvery pubescence; segment VIII brown. Body: Length, 1.99–2.10 mm (mean ± SD = 2.05 ± 0.04 mm); width, 0.73–0.76 mm (0.74 ± 0.01 mm), 2.72–2.82 times as long as wide. Head (Fig. 19): Short and wide, length, 0.38–0.43 mm (0.41 ± 0.02 mm); width, 0.52–0.54 mm (0.53 ± 0.01 mm), 1.21–1.38 times as wide as long; eyes with many short hairs (Figs. 19–20); antenna 0.47–0.54 times as long as body, lengths of antennal segments I–IV as follows: I, 0.32–0.33 mm (0.32 ± 0.00 mm); II, 0.20–0.22 mm (0.21 ± 0.01 mm); III, 0.19–0.21 mm (0.21 ± 0.01 mm); IV, 0.27–0.33 mm (0.31 ± 0.02 mm). Pronotum: Broad, length, 0.44–0.47 mm (0.45 ± 0.01 mm); width, 0.67–0.69 mm (0.68 ± 0.01 mm), 1.47–1.54 times as wide as long; bearing dense black punctures scattered all over except the anterior part, posterior margin of pronotum arched, anterior margin slightly emarginated, mesonotum and metanotum hidden under pronotal lobe except laterally, mesopleuron slightly larger than metapleuron. Legs: Fore leg (Fig. 12) short, femur simple, with many short and long hairs; tibia with dense short setae ventrally, grasping comb from half to apex ventrally (Fig. 13); middle leg (Fig. 14) long, femur simple, with many short and long hairs, tibia with dense short setae from half to near apex ventrally and at apex, with black long setae from half to near apex in inner margin; hind leg (Fig. 15) long, femur simple, with many short and long hairs, tibia slightly curved to inner dorsal part, with dense short setae apex ventrally, tarsomere I with 4–5 long swimming bristles along posterior margin, tarsomere II 1.20–1.59 times as long as tarsomere I; femur, tibia, and tarsus (middle and hind leg include tarsomere I and II) lengths: fore leg: 0.55–0.57 mm (0.56 ± 0.00 mm), 0.49–0.51 mm (0.50 ± 0.01 mm), and 0.25–0.27 mm (0.26 ± 0.01 mm), respectively; middle leg: 0.70–0.71 mm (0.70 ± 0.00 mm), 0.67– 0.69 mm (0.68 ± 0.01 mm), 0.15–0.18 mm (0.17 ± 0.01 mm), and 0.28–0.31 mm (0.29 ± 0.01 mm), respectively; hind leg: 0.69–0.74 mm (0.72 ± 0.02 mm), 0.76–0.80 mm (0.78 ± 0.02 mm), 0.19–0.24 mm (0.22 ± 0.01 mm), and 0.29–0.31 mm (0.29 ± 0.01 mm), respectively. Abdomen: Slightly narrower toward rear; mediotergites flat, segments II–V subequal in length, VII the longest, I–VI obviously wider than long, VII slightly wider than long; laterotergites slightly raised. Genital segments (Figs. 16–18, 21–24): Segment VIII (Figs. 16–18, 21–23) about 1.5 times as long as wide, posterior margin with many light-brown hairs, large circle-shaped depression ventrally, this depression 0.6 times ventral length, middle anterior margin with clump of very short setae, middle to anterior of this depression with a row of 8 short spine-like setae, lateral portion of this depression with many punctures, lateral and posterior margins with dense spine-like setae, middle part of posterior margin with a cluster of spines; pygophore (Fig. 24) small, rounded, many light-brown hairs.

Apterous female (Figs. 3–4, 6, 8). Structures similar to those of apterous male. Body larger than that of male. Body: Length, 2.47–2.61 mm (2.54 ± 0.05 mm); width, 0.88–0.95 mm (0.94 ± 0.02 mm). Head: Length, 0.46–0.51 mm (0.49 ± 0.02 mm); width, 0.61–0.62 mm (0.62 ± 0.01 mm), 1.21–1.34 times as wide as long; antenna 0.47–0.51 times as long as body, lengths of antennal segments I–IV as follows: I, 0.36–0.38 mm (0.37 ± 0.01 mm); II, 0.24– 0.27 mm (0.26 ± 0.01 mm); III, 0.25–0.26 mm (0.25 ± 0.00 mm); IV, 0.34–0.36 mm (0.35 ± 0.01 mm). Pronotum: Length, 0.51–0.62 mm (0.57 ± 0.04 mm); width, 0.76–0.77 mm (0.77 ± 0.01 mm), 1.26–1.52 times as wide as long. Legs: Fore tibia without grasping comb, hind tibia straight, tarsomere I without swimming bristles (Figs. 4, 6); femur, tibia, and tarsus (middle and hind leg include tarsomere I and II) lengths: fore leg: 0.67–0.70 mm (0.69 ± 0.01 mm), 0.54–0.58 mm (0.56 ± 0.02 mm), and 0.33–0.35 mm (0.34 ± 0.01 mm), respectively; middle leg: 0.85–0.91 mm (0.88 ± 0.02 mm), 0.82–0.88 mm (0.84 ± 0.02 mm), 0.19–0.21 mm (0.20 ± 0.01 mm), and 0.34–0.38 mm (0.37 ± 0.01 mm), respectively; hind leg: 0.91–0.94 mm (0.92 ± 0.01 mm), 0.99–1.03 mm (1.02 ± 0.01 mm), 0.22–0.24 mm (0.23 ± 0.01 mm), and 0.34–0.36 mm (0.35 ± 0.01 mm), respectively; hind tarsomere II 1.42–1.62 times as long as tarsomere I. Abdomen (Fig. 3): Mediotergites flat, segment I longest, I–VIII wider than long, posterior margin of segment VI ventrally not straight, weakly convex with a median depression (Fig. 4); laterotergites broad, slightly raised.

Macropterous male and female. Unknown.

Etymology. The specific epithet “ lasiomma ” means hairy eyes.

Diagnosis. Pseudovelia lasiomma sp. nov. can be distinguished from 25 species and two subspecies by eyes with dense hairs (Table 1). Pseudovelia intonsa Hecher, 1997, P. longitarsa Andersen, 1983, and P. sexualis (Paiva, 1917) are similar to P. lasiomma sp. nov. with dense hairs on the eyes, but can be distinguished by the following combination of characteristics: hind tibia longer than tarsus (tarsus longer than tibia in P. longitarsa); grasping comb approximately half of fore tibia length (<0.5 times tibia length in P. intonsa, and>0.5 times tibia length in P. longitarsa and P. sexualis); hind tarsomere I with 4–5 long swimming bristles along posterior margin (tarsomere I without long swimming bristles in P. intonsa, and tarsomere I with long swimming bristles only on basal portion in P. longitarsa); hind tarsomere I straight (tarsomere I curved in P. longitarsa); body shape parallel-sided (body shape slightly oval, metanotum widest in P. sexualis); interocular distance wide (interocular distance narrow in P. sexualis); most of dense hairs on eyes longer than diameter of ommatidium (dense hairs on eyes shorter in P. sexualis: See Andersen (1983: fig. 6)); 2–3 swimming bristles on hind tarsomere I longer than length of tarsomere I, length of swimming bristles vary (all swimming bristles on hind tarsomere I shorter than length of tarsomere I, length of swimming bristles differences scarce in P. sexualis: See Andersen (1983: fig. 11)); posterior margin of ventral depression of segment VIII with a cluster of spines (posterior margin of ventral depression of segment VIII without a cluster of spines in P. sexualis: See Andersen (1983: fig. 13)). Among the Japanese species of Pseudovelia, P. lasiomma sp. nov. is similar to P. esakii, but can be distinguished by the following combination of characteristics: eyes with dense hairs (Figs. 19–20) (eyes bare with only two ocular setae in P. esakii: Figs. 25–26); abdominal segment VIII with large circle-shaped depression (long horizontal oval-shaped depression in P. esakii: Figs. 27–28); middle area and lateral margin of this depression with row of setae (middle area and lateral margin of this depression with cluster of setae in P. esakii: Figs. 27–28).

Remarks. The first author observed more than 200 adults, including breeding individuals and the type series. Macropterous males and females have not been found, although macropterous adults have been recorded for all other species of Japanese Pseudovelia: P. esakii, P. hirashimai, P. takarai, P. tibialis tibialis, P. tsutsuii (Hayashi & Miyamoto 2018; Hirasawa 2019). Pseudovelia lasiomma sp. nov. and P. sexualis have many common characteristics and may be closely related. The distributions of the two species are relatively widely separated, which is an important consideration in speciation studies. Elucidation of the barcode region will clarify the relationship between the two species.

Distribution. Japan (Lake Biwa) (Fig. 11).

Biology. This species inhabits the land at the lake margins and was found mostly within ca. 20 cm of the edge. The individuals were discovered in gaps, under driftwood, and on water plants. The nymphal appearance period in the type locality includes late autumn, as the nymphs were found on November 3, 2022 (Figs. 9–10).

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Key to the species of Pseudovelia from Japan

The key is applicable to apterous males and is based on Esaki & Miyamoto (1955), Miyamoto (1959, 1964), Ye et al. (2013), Ye & Bu (2016), Hayashi & Miyamoto (2018), and Li et al. (2022).

1. Eyes with dense hairs (males and females). Distribution: Japan (Honshu; Lake Biwa)......................................................................................... Pseudovelia lasiomma Watanabe et Hayashi, sp. nov.

- Eyes bare with only two ocular setae..................................................................... 2

2. Middle tibia with a tuft of stout bristles near apex on anterior margin; grasping comb of fore tibia> 0.5 times as long as tibia. Distribution: Japan (Hokkaido, Honshu, Okino-shima Is., Shikoku, Kyushu, Tsushima Is., Shimo-koshikishima Is., Yaku-shima Is., Nakano-shima Is.), Russia, China, Korea, Vietnam ..................... P. tibialis tibialis Esaki & Miyamoto, 1955

- Middle tibia without a tuft of stout bristles near apex on anterior margin; grasping comb of fore tibia ≤ 0.5 times as long as tibia............................................................................................... 3

3. Medial portion of fore tibia with distinct process; hind tarsomere II more than twice as long as tarsomere I; hind tarsomere I with eight swimming bristles; antennal segment I longer than segment IV. Distribution: Japan (Ishigaki-jima Is., Iriomote-jima Is.), China ..................................................................... P. takarai Miyamoto, 1964

- Medial portion of fore tibia without distinct process; hind tarsomere II less than 1.3 times as long as tarsomere I; hind tarsomere I with fewer than four swimming bristles; antennal segment I the same length as or shorter than segment IV............. 4

4. Tarsomere II of hind leg shorter than tarsomere I. Distribution: Japan (Honshu)................ P. esakii Miyamoto, 1959

- Tarsomere II of hind leg the same length as or longer than tarsomere I. Distribution: Takara-jima Island and southward.... 5

5. Antennal segment I shorter than segment IV; hind tarsomere I the same length as tarsomere II; hind tarsomere I with three long swimming bristles. Distribution: Japan (Ishigaki-jima Is., Iriomote-jima Is., Yonaguni-jima Is.)................................................................................................... P. hirashimai Miyamoto, 1964

- Antennal segment I the same length as segment IV; hind tarsomere I shorter than tarsomere II; hind tarsomere I with two long swimming bristles and one short bristle. Distribution: Japan (Takara-jima Is., Amami-oshima Is., Kikai-jima Is., Tokuno-shima Is., Okinawa-jima Is., Iheya-jima Is., Tokashiki-jima Is., Aka-jima Is., Zamami-jima Is.).................................................................................................... P. tsutsuii Esaki & Miyamoto, 1955