Cybaeus koikei,

Sugawara, Yusuke, Ihara, Yoh & Nakano, Takafumi, 2021, A new species of Cybaeus L. Koch, 1868 (Araneae, Cybaeidae) with simple genitalia from central Japan is the sister species of C. melanoparvus Kobayashi, 2006 with elongated genitalia, Zoosystematics and Evolution 97 (1), pp. 223-233: 223

publication ID

http://dx.doi.org/10.3897/zse.97.64473

publication LSID

lsid:zoobank.org:pub:93DA2C6A-37A0-4AF7-8C17-B90FC041BB0C

persistent identifier

http://treatment.plazi.org/id/30DB7CE2-EDD2-49D7-9CD4-F508B82FACFC

taxon LSID

lsid:zoobank.org:act:30DB7CE2-EDD2-49D7-9CD4-F508B82FACFC

treatment provided by

Zoosystematics and Evolution by Pensoft

scientific name

Cybaeus koikei
status

sp. nov.

Cybaeus koikei  sp. nov. Figures 4View Figure 4, 5View Figure 5, 6View Figure 6, 7View Figure 7

Diagnosis.

‘Small-sized’ Japanese Cybaeus  . Both sexes of C. koikei  are most similar to those of C. melanoparvus  . Although males of these two species resemble each other in lacking a palpal PA and having a palpal tibia that is almost as long as the palpal patella (Figs 6CView Figure 6, 8DView Figure 8), they can be clearly distinguished by their simple and small palpal bulb (Fig. 6BView Figure 6) whereas C. melanoparvus  have a well-developed palpal bulb (Fig. 8BView Figure 8). Females of C. koikei  are clearly distinguishable by their relatively simple spermathecae (Fig. 6EView Figure 6); C. melanoparvus  has highly complex spermathecae (Fig. 8FView Figure 8).

Material examined.

Holotype: Japan • ♂; Kyoto Prefecture, Kyoto City, Sakyo, Hanase Pass ; 35°9.98'N, 135°47.58'E; 14 Oct. 2020; T. Nakano leg.; under a stone along a mountain stream; KUZ Z3744GoogleMaps  . Paratypes: Japan • 1 ♀; same locality as for holotype; 35°09.85'N, 135°47.51'E; 14 Oct. 2020; T. Nakano leg.; under a stone along a forest trail; KUZ Z3743GoogleMaps  1 ♂; same locality as for holotype; 35°9.65'N, 135°47.19'E; 24 Sep. 2012; N. Koike leg.; KUZ Z2364GoogleMaps  1 ♂; same data as for preceding; NSMT-Ar 20964GoogleMaps  8 ♀♀; same data as for preceding; KUZ Z2365GoogleMaps  1 ♀; same data as for preceding; KUZ Z3741GoogleMaps  ; 1 ♀; same data as for preceding; NSMT-Ar 20965GoogleMaps  .

Additional specimens: Japan • 1 ♂; Kyoto Prefecture, Nantan City, Ashiu ; 35°17.97'N, 135°44.19'E; 14 Nov. 2007; N. Koike leg.; KUZ Z2335GoogleMaps  1 ♀; Kyoto Prefecture, Kyoto City, Kita, Kumogahata-detanicho ; 35°7.92'N, 135°42.7'E; 7 Nov. 2012; N. Koike leg.; KUZ Z2419GoogleMaps  4 ♀♀; same data as for preceding; KUZ Z3742GoogleMaps  1 ♂; Shiga Prefecture, Takashima City, Yokotani Valley ; 35°18.34'N, 135°53.96'E; 21 Oct. 2020; Y. Sugawara leg.; under a stone along a mountain stream; KUZ Z3748GoogleMaps  1 ♀; same data as for preceding; KUZ Z3745GoogleMaps  1 ♀; same data as for preceding; KUZ Z3747GoogleMaps  1 juv.; same data as for preceding; KUZ Z3746GoogleMaps  1 ♀; same locality as for holotype; 35°9.46'N, 135°47.24'E; 16 Oct. 2019; K. Matsuda leg.; under a stone along a mountain stream; KUZ Z2824GoogleMaps  2 ♀♀; same locality as for holotype; 18 Jun. 2008; N. Koike leg.; KUZ Z3751GoogleMaps  1 ♀; same locality as for holotype; 30 Nov. 2008; N. Koike leg.; KUZ Z3752GoogleMaps  1 ♂; Kyoto Prefecture, Kyoto City, Sakyo, Ohara-kochihiracho , Amida  -ji Temple ; 35°8.27'N, 135°49.64'E; 2 Nov. 2008; N. Koike leg.; sifted from fallen leaves; KUZ Z3753GoogleMaps  1 ♂; Shiga Prefecture, Otsu City, Mt. Shirataki ; 35°14.61'N, 135°52.57'E; 24 Oct. 2012; N. Koike leg.; KUZ Z3754GoogleMaps  3 ♂♂; same data as for preceding; KUZ Z3755GoogleMaps  6 ♀♀; same data as for preceding; KUZ Z3756GoogleMaps  1 ♀; same data as for preceding; KUZ Z3757GoogleMaps  4 ♂♂; Shiga Prefecture, Otsu City, southeast of Mt. Horai ; 35°11.81'N, 135°53.49'E; 24 Oct. 2012; N. Koike leg.; KUZ Z3759GoogleMaps  1 ♀; same data as for preceding; KUZ Z3758GoogleMaps  6 ♀♀; same data as for preceding; KUZ Z3760GoogleMaps  5 ♂♂; Fukui Prefecture, Tsuruga City, Mt. Nosaka ; 35°36.16'N, 136°1.66'E; 25 Oct. 2012; N. Koike leg.; along a forest trail; KUZ Z3762GoogleMaps  1 ♀; same data as for preceding; KUZ Z3761GoogleMaps  9 ♀♀; same data as for preceding; KUZ Z3763GoogleMaps  .

Type locality.

Japan, Kyoto Prefecture, Kyoto City, Sakyo, Hanase Pass (35°9.98'N, 135°47.58'E).

Description.

Male (holotype, KUZ Z3744; Figs 4AView Figure 4, 5A, BView Figure 5). Measurements (mm). CL 2.04, CW 1.53; head 0.91 wide; abdomen 1.71 long, 1.32 wide; ocular area 0.27 long, 0.59 wide; sternum 0.95 long, 0.93 wide. Leg formula, IV > I > II > III; length of legs (femur + patella + tibia + metatarsus + tarsus): leg I 6.03 (1.70 + 0.68 + 1.44 + 1.41 + 0.80); leg II 5.58 (1.55 + 0.64 + 1.28 + 1.33 + 0.78); leg III 4.96 (1.41 + 0.58 + 0.93 + 1.26 + 0.77); leg IV 6.31 (1.67 + 0.60 + 1.41 + 1.75 + 0.87).

Carapace (Fig. 5AView Figure 5). Head narrow, ca. 0.59 × as wide as thoracic region; thoracic region almost as high as head. AER straight in frontal view; PER almost straight in dorsal view; AME smallest, < 1/2 diameter of other eyes; ocular area ca. 2.1 × wider than long. Clypeus shorter than median ocular area.

Mouthparts. Chelicerae slightly geniculate, promargin of fang furrow with 3 teeth (median one largest), retromargin with 4 teeth and 3 or 4 denticles, and basally with lateral condyle. Labium wider than long.

Leg macrosetae. Leg I: tibia p4, r0, v2-2-2-2; metatarsus p4, r1, v2-2-2. Leg II: tibia p3, r0, v2-2-2-2; metatarsus p4, r2, v2-2-3.

Abdomen (Fig. 5BView Figure 5). Oval; mid-posterior part widest. Colulus with two groups of 1 or 2 setae.

Palp (Fig. 6A-CView Figure 6). Patella without PA, lateral surface covered with cluster of robust setae. Tibia almost as long as patella; RTA plate-like, occupying 2/3 of length of tibia. Cymbium ca. 2 × longer than wide, slightly expanded prolaterally. Genital bulb circular in ventral view. Conductor: distal part unelongated; proximal arm short, hooked. Embolus simple, originating and terminating, respectively, at ca. 11 o’clock and ca. 5 o’clock in ventral view.

Color (Fig. 5A, BView Figure 5). Carapace: head brown, with reticulate dark brown markings; thoracic region yellowish brown, with radiating dark brown bands. Chelicerae, maxillary lobe and labium yellowish brown. Sternum beige. Legs beige to yellowish brown, darker distally, with pale to dark brown annulations. Abdomen: dorsally dark olive-brown with pale brown chevron-like markings; ventrally pale brown.

Female (paratype, KUZ Z3743; Fig. 5C, DView Figure 5). Measurements (mm). CL 2.17, CW 1.51; head 1.00 wide; abdomen 2.03 long, 1.35 wide; ocular area 0.31 long, 0.66 wide; sternum 1.00 long, 0.98 wide. Leg formula, IV > I > II > III; length of legs (femur + patella + tibia + metatarsus + tarsus): leg I 5.39 (1.57 + 0.62 + 1.34 + 1.20 + 0.66); leg II 5.05 (1.54 + 0.60 + 1.13 + 1.14 + 0.64); leg III 4.51 (1.35 + 0.55 + 0.89 + 1.10 + 0.61); leg IV 5.71 (1.64 + 0.60 + 1.30 + 1.45 + 0.72).

Carapace (Fig. 5CView Figure 5). Head ca. 0.66 × as wide as thoracic region; thoracic region slightly higher than head. AER almost straight in frontal view; PER slightly recurved in dorsal view; AME smallest, < 1/2 diameter of other eyes; ocular area ca. 2.1 × wider than long. Clypeus shorter than median ocular area.

Mouthparts. Chelicerae slightly geniculate, teeth and denticles of fang furrow not observable and covered by long setae; basally with lateral condyle. Labium wider than long.

Leg macrosetae and abdomen (Fig. 5DView Figure 5). Same as for male holotype.

Genitalia (Figs 6D, EView Figure 6, 7View Figure 7). Posterior margin of epigynal plate weakly ‘M’ -shaped. Atrium located posteromedially on epigyne and with 2 distinct copulatory openings. CPs separated on both sides of atrium; CD long running anteromedially. Each of SH and SS slightly bulbous; SH small, with a few primary pores anteromedially; SS running posteromedially; SB large, globular, directed anterolaterally; Bennett’s gland located anteriorly at connection between SS and SB.

Colour (Fig. 5C, DView Figure 5). Carapace: head brown, with reticulate dark brown markings; thoracic region yellowish brown, with radiating dark brown bands. Chelicerae, maxillary lobe and labium dark yellowish-brown. Sternum light yellowish-brown. Legs pale brown to yellowish brown, darker distally, with medium to dark brown annulations. Abdomen: dorsally dark olive-brown with pale brown chevron-like markings; ventrally light yellowish-brown to brown.

Variation.

Males. Measurements (mean ± 1SD, followed by ranges in parentheses; n = 19, including holotype and paratypes): CL 2.05 ± 0.11 (1.87-2.23), CW 1.50 ± 0.10 (1.33-1.65); CW/CL 0.73 ± 0.03 (0.70-0.82); TibIL 1.45 ± 0.07 (1.31-1.59); TibIL/CL 0.71 ± 0.02 (0.68-0.74). Legs longer than those of females.

Females. Measurements (n = 42, including paratypes): CL 2.06 ± 0.17 (1.67-2.31), CW 1.41 ± 0.12 (1.06-1.57); CW/CL 0.68 ± 0.02 (0.64-0.75); TibIL 1.30 ± 0.12 (1.04-1.51); TibIL/CL 0.63 ± 0.03 (0.53-0.68).

Etymology.

The specific name is dedicated to Mr Naoki Koike who assembled the large collection of Japanese Cybaeus  spiders that is now kept at Kyoto University, including the specimens of this new species.

Remarks.

This species constructs a ‘V-shaped’ retreat (Fig. 4BView Figure 4), which is the most common type of retreat among Japanese Cybaeus  ( Ihara 2006, 2009b; Ihara et al. 2021). Because all specimens collected in 2019 and 2020 were found under stones, it is possible that this species prefers to construct its retreat on the underside of stones rather than in decaying substrates.

According to the nuclear ITS-1 sequences obtained from the holotype male ( KUZ Z3744) and the paratype female ( KUZ Z3743), the males and females examined in this study clearly belong to the same species newly described here. Their ITS-1 sequences through the overlapping aligned positions (451 bp) are completely identical to each other.

Two species, C. daimonji  and C. kiiensis  Kobayashi, 2006 whose spermathecae are grouped into 'type 1', occur in sympatry with C. koikei  sp. nov. through montane habitats on the western side of Lake Biwa. However, they are clearly distinguishable by body size: the body length of C. koikei  sp. nov. reaches ca. 4 mm whereas that of C. daimonji  and C. kiiensis  reaches ca. 6 mm and ca. 2.5 mm, respectively ( Kobayashi 2006; Matsuda et al. 2020). Additionally, males of C. koikei  sp. nov. are conclusively distinguishable from those of C. daimonji  and C. kiiensis  by the lack of PA on its palp. Males of both C. daimonji  and C. kiiensis  possess a PA on their pedipalp ( Kobayashi 2006; Matsuda et al. 2020).

Kingdom

Animalia

Phylum

Arthropoda

Class

Arachnida

Order

Araneae

Family

Cybaeidae

Genus

Cybaeus