Parachauliodes rastellus, Shimonoya, 2019

Shimonoya, Mitsuru, 2019, A new species of the genus Parachauliodes (Megaloptera: Corydalidae: Chauliodinae) from Northern Kyushu, Japan, Zootaxa 4585 (1), pp. 151-167 : 152-166

Parachauliodes rastellus sp. nov.

[New Japanese name: Chikushi-kurosuji-hebitombo]

( Figs. 2 , 4–9 )

Type material. Holotype: ♂ ( UMUT), [KYUSHU, JAPAN], Saga Prefecture, Takeo-shi, Takeo-cho, Nagashima (altitude 30 m), 19.IV.2018 (M. Shimonoya leg.) . Paratypes: 9♂ 4♀ (M. Shimonoya leg.); the same locality as holotype , 1♂ 13.V.2017, 1♂ 14.I.2018 larva collected and emerged on 29.IV.2018, 1♂ 12.IV.2018, 1♂ 20.IV.2018; Takeo-shi, Takeo-cho, Takeo (altitude 18 m) , 2♂ 19.IV.2018, 1♂ 20.IV.2018; [KYUSHU, JAPAN], Fukuoka Prefecture, Munakata-shi, Takemaru (altitude 38 m) , 2♂ 16.I.2018 larvae collected and emerged on 19.IV.2018, 30.IV.2018; 4♀ 16.I.2018 larvae collected and emerged on 24.IV.2018, 30.IV.2018, 1.V.2018, 6.V.2018. Larvae in alcohol all 11 exs. (M. Shimonoya leg.); Fukuoka Prefecture, Munakata-shi, Takemaru (altitude 38 m), 10 exs. 3. VI.2017 ; the same locality as holotype, 1ex. 7.IV.2018 .

Etymology. The specific epithet “rastellus”, from the Latin for small rake ( Fig. 3 ), refers to the rake-like male antenna of the new species.

Diagnosis. Forewing with many brownish small spots; RP four (or five) -branched, only one branch from rarp2. Male antenna pectinate with short branches, female antenna serrate. Male ectoprocts bilobed, inner surface of dorsal lobe with rows of blackish brush-like spinous setae; gonocoxites 10 in lateral view median plate with tip prominently curved dorsad and directed posteriorly, in ventral view median plate teaspoon-like with rounded tip.

Description. Adult. Male. Body length average 37 mm (31–40 mm, n=6; measured while alive because abdomen shrinking after death), forewing length 44 mm (38–49 mm, n=10), hindwing length 40 mm (34–44 mm, n=10), antenna length 23 mm (17–26 mm, n=10).

Head dark ochreous, with blackish thick line markings on genae, vertex dark brown, with ochreous longitudinal streaks. Compound eyes dark brown. Ocelli, median ocellus greyish yellow, lateral ocelli brown, with black inner margins ( Fig. 2B ). Antenna blackish brown, flagellum 55–69 (average 62, n=9) segments; proximal half, pectinate with short clavate branches; from half toward tip, gradually modified to serrate; approximately 10 segments of apex moniliform ( Fig. 5A ). Mouthparts brown.

Prothorax greyish dark green, lateral and posterior margin brown to greyish dark brown ( Fig. 4A ). Legs dark brown with dense setae, coxae to tibiae greyish dark green to brown, tarsi and tarsal claws blackish brown. Wings elongated, pale smoky brown. Forewing pterostigmatic area dark brown, with many brownish small spots, three indistinct small dark-brownish nygmata between RP and MA. Hindwing much paler than forewing, two indistinct small dark-brownish nygmata between RP and MA. Veins dark brown, crossveins white. RP four (or five) - branched, only one branch from rarp2, three crossveins between RA and RP. M two-branched, four crossveins between RP and MA, four crossveins between M to MP and CuA to CuA1, usually (89.3%, n=14) two crossveins between MP and CuA1, two crossveins between CuP and A1. A1 two-branched, with posterior branch sinuated. A2 two-branched, with anterior branch sinuated, posterior branch strongly sinuated ( Fig. 6 ).

Abdomen brown to blackish brown. Tergite 9 brown with setae, in dorsal view wider than long, anteriorly concave, posteriorly convex, with arcuate anterior incision, and center of posterior margin with slightly concaved medially ( Fig. 7A ), in lateral view subquadrate, with ventral posterior corner roundly produced ( Fig. 7C ). Sternite 9 with semicircular membranous process. Ectoprocts bilobed, in lateral view subovate, and slightly incised medially ( Fig. 7C ), in ventral view ventral lobe developed with slightly angular tip and inner margin slightly curved convexly, with shallow longitudinal incision on outer portion, distally inner surface of dorsal lobe with rows of blackish brush-like spinous setae ( Fig. 7B ). Callus cerci large, not prominent. Gonocoxites 10 sclerotized with a pair of lateral arms (amalgamated with gonocoxites 9), in lateral view median plate with tip prominently curved dorsad and directed posteriorly, dorsally basal area of median plate ridged widely ( Fig. 7D ), in ventral view median plate teaspoon-like with rounded tip ( Fig. 7B ).

Female. Body length average 45 mm (42–49 mm, n=4; measured while alive), forewing length 47 mm (45–48 mm, n=4), hindwing length 42 mm (41–43 mm, n=4), antenna length 20 mm (19–20 mm, n=4).

Coloration and general morphology, except antenna and genitalia, almost same as in male. Antenna blackish brown, flagellum 60–64 (average 61, n=3) segments; serrate, approximately 10 segments of apex moniliform ( Fig. 5B ).

Gonocoxites 8 in lateral view nearly subtrapezoidal with posterior margin produced. Ectoprocts in lateral view digitiform, in ventral view subtriangular. Callus cerci not prominent. Gonocoxites 9 in lateral view foliate with pointed tip, broad, wider than ectoprocts ( Figs. 7E, 7F ).

Larva (last instar). Head width, male 4.2–5.2 mm (n=3), female 6.1–7.1 mm (n=4); body length, male 39–43 mm, female 51–58 mm, impossible to determine sexes of larvae from external features until pupation.

Head black and shiny, with punctures. Antenna brown. Clypeus light brown. Mandible black and shiny, with left mandible four teeth, with right three teeth on inner margin in addition to apical tooth.

Prothorax black and shiny, with punctures, medially paired shallow dents; mesothorax and metathorax brown, dorsally blackish thick line marking. Legs, coxae dark brown, trochanter to tarsi brown with dense setae, claws dark brown.

Abdominal segments I to VIII unsclerotized, with paired lateral abdominal filaments, dorsal coloration greyish brown, with ochreous small spots, indistinct mid-dorsal longitudinal stripe dark brown ( Fig. 8A ); ventral coloration dark brown, with ochreous small spots ( Fig. 8C ). Paired respiratory tubes on the segment VIII, cylindrical, contiguous at bases, apices narrow and white, with blackish band (also found on exuvium), length of tube 1.1 to 1.3 times as long as basal width of tubes ( Fig. 8D ). Segment IX narrower than VIII. Segment X paired anal prolegs, with two brownish hook-shape claws.

Distribution. Japan, northern Kyushu, Saga and Fukuoka Prefectures.

Habitat. The larvae of the new species occur shallow streams with substrate that includes few rocks and stones at an altitude of 20 to 50 m.

Ecology. Adults and larvae are active nocturnally. Adult males of the new species are attracted to lights at night. The flying behavior of female at night is unknown. Adult emergence period overlaps to some extent between the new species and P. japonicus . Larvae burrow under fallen leaves, sand, or mud in the water diurnally and are nocturnally active moving on the surfaces of benthic sediments.

2: Parachauliodes rastellus sp. nov. holotype male wing venation. scale bar: 10 mm.

Pupation and emergence. Lateral abdominal filaments of last instar larvae were observed to become wilted, indicating pupation was near. The larvae left the stream and excavated a pupal chamber in moist soil. At room temperature of approximately 24°C, the combined prepupal and pupal stages durations averaged 18 days (both sexes 13–22 days, n=7; male 16–22 days, n=3; female 13–20 days, n=4).

Copulation. The next day after emergence, a female mated with a male. Copulation occurred at night. The following day after mating, the male mated with another female. The mating positions in the rearing cage were vertical ( Fig. 9A ).

Oviposition. Description of oviposition (one female). The next day after mating, the female laid eggs. Oviposition occurred at night. First, the female held onto a branch with head downward and soon began to oscillate the terminal segment of abdomen slowly as she gradually descended the branch, laying 1,576 eggs around the branch closely with rows in one layer deep in one batch. Duration of oviposition extended over approximately three hours and an average of 8 to 9 eggs are laid per minute ( Figs. 9B, 9C ). The female continued to descend the branch without laying eggs and oscillating her terminalia to the left and right slowly for about five minutes before leaving the branch.

Eggs. Length 0.9 mm, width 0.3 mm, elongate ovate, with micropylar process, coloration light grey with translucent, elliptical shadow of an embryo in the egg, center dark brown, surroundings deep green. Micropylar process pale yellow ( Fig. 9D ).

Hatching. The eggs hatched 17 days after oviposition at room temperature of 24°C. Hatching lasted for four days from one egg mass. The egg chorion was cut by mandible of each larva near the micropylar region and the head of the larva was gradually advanced over 8 to 9 minutes ( Fig. 9E ).

First instar larvae walked on the egg mass until the sclerotization was complete ( Figs. 9F, 9G ), and dropped in the water below. Lateral abdominal filaments were observed to stick to the abdomen of the larvae and to unfold after they fell into the water ( Figs. 9H, 9I ).

Remarks. Parachauliodes rastellus is most similar to the sympatric P. japonicus . Parachauliodes japonicus is widely distributed in Honshu, Shikoku, Kyushu, Fukue Island, and Yaku Island in Japan ( Liu et al., 2008), but the geographical variation of P. japonicus is poorly known, except for specimens from Fukue Island that have blackish wings ( Liu et al., 2008). To minimize the influence of geographical variation, sympatric populations of both the new species and P. japonicus (18 larvae) from Saga Prefecture, Takeo-shi, Takeo-cho, Nagashima, altitude 22 to 45 m and Fukuoka Prefecture, Onga-gun, Okagaki-machi, Joubata (adjacent to the locality of paratypes), Mt. Jouyama, altitude 140 m were reared and directly compared.

In adult, Parachauliodes rastellus appears to be similar to P. japonicus in having a similar longitudinal venation of wings with only one branch from rarp2 ( Kuwayama, 1962), and the male gonocoxites 10 median plate with rounded tip, but it can be distinguished from P. japonicus by the following characters: 1) male antenna pectinate with short branches ( Fig. 5A ), 2) crossveins between MP and CuA1 usually two ( Fig. 6 ), 3) coloration of lateral and posterior margin of prothorax brown to greyish dark brown ( Figs. 4A, 4B ), and 4) male ectoprocts ventral lobe developed with slightly angular tip, with shallow longitudinal incision on outer portion ( Fig. 7B ). In P. japonicus , 1) male antenna serrate ( Figs. 10A, 10B ), 2) crossvein between MP and CuA1 usually one (91.7%, n=18) ( Figs. 10A, 10C ), 3) coloration of lateral and posterior margin of prothorax ochreous (brown preserved) ( Figs. 10B, 10D ), and 4) male ectoprocts ventral lobe developed with rounded tip, and incision on outer portion almost absent.

In last instar larva, P. rastellus appears to be similar to P. japonicus with the respiratory tubes on the abdominal segment VIII cylindrical and contiguous at bases, but it can be distinguished by the following characters: 1) coloration of apices of respiratory tubes white, with blackish band ( Figs. 8D, 8E ), 2) length of tubes 1.1 to 1.3 times as long as basal width of tubes ( Fig. 8D ), and 3) ventral coloration of abdomen dark brown, with ochreous small spots ( Fig. 8C ). In P. japonicus , 1) coloration of apices of tubes white, without the blackish band ( Figs. 10G, 10H ), 2) the length of tubes relatively short compared with that of P. rastellus , 1.0 to 1.1 times as long as basal width of tubes ( Fig. 10G ), and 3) ventral coloration of abdomen medially ochreous with laterally brownish small spots ( Fig. 10F ).

Figures

FIGURE 2. Parachauliodes rastellus sp. nov. A. holotype male, B. holotype male (head enlarged), C. paratype female, D. paratype female (head enlarged). scale bars: 10 mm.

FIGURE 3. Photograph of small rake.

FIGURE 4. Parachauliodes rastellus sp. nov. A. holotype male (alive), B. paratype female (alive).

FIGURE 5-6. 1: Parachauliodes rastellus sp. nov. A. male antenna, B. female antenna. scale bars: 1 mm.

FIGURE 7. Parachauliodes rastellus sp. nov. A. male genitalia, dorsal view, B. male genitalia, ventral view, C. male genitalia, lateral view, D. male gonocoxites 10, lateral view, E. female genitalia, lateral view, F. female genitalia, ventral view. c: callus cercus, e: ectoproct, gx: gonocoxite, S: sternite, T: tergite. scale bars: 1 mm.

FIGURE 8. Parachauliodes rastellus sp. nov. larva (last instar, alive). A. whole body, dorsal view, B. whole body, lateral view, C. abdomen, ventral view, D. respiratory tubes, dorsal view, E. respiratory tubes, lateral oblique view. scale bar: 5 mm.

FIGURE 9. Parachauliodes rastellus sp. nov. A. copulation, B. oviposition, C. fresh egg mass, D. fresh eggs (enlarged), E. hatching process, F to I. first instar larvae, F. larvae on the egg mass (enlarged), G. larvae on the egg mass, H. dorsal view, I. lateral view. scale bars: 10 mm (C), 1 mm (D, H).

FIGURE 10. Parachauliodes japonicus. A. male, B. male (alive, enlarged), C. female, D. female (alive, enlarged), E to H. larva (last instar, alive), E. whole body, dorsal view, F. abdomen, ventral view, G. respiratory tubes, dorsal view, H. respiratory tubes, lateral oblique view. scale bars: 10 mm (A, C), 5 mm (E).