Cybaeus daimonji, Matsuda & Ihara & Nakano, 2020

Matsuda, Kenji, Ihara, Yoh & Nakano, Takafumi, 2020, Description of a New Species of Cybaeus (Araneae: Cybaeidae) from Central Honshu, Japan, Species Diversity 25, pp. 145-152 : 146-150

Genus Cybaeus L. Koch, 1868 Cybaeus daimonji sp. nov. [New Japanese name: Daimonji-namihagumo] ( Figs 1–5 )

Diagnosis. “Medium-sized” Japanese Cybaeus . Females of C. daimonji sp. nov. resemble those of C. communis Yaginuma, 1972 , C. kirigaminensis Komatsu, 1963 , C. maculosus Yaginuma, 1972 and C. shinkaii ( Komatsu, 1970) , which also are “medium-sized” and have a similar posteromedially located atrium and inverted V-shaped spermathecae [figs 2-2-30- 18–23 in Ihara (2009a)]. However, females of C. daimonji sp. nov. can be discriminated from those of the other four species by the copulatory ducts running toward the medial part of respective spermathecae, while in the other four congeners the copulatory ducts run directly toward the respective spermathecal heads [for C. communis , based on an unpublished observation by Yoh Ihara; for C. kirigaminensis , pl. 4, fig. H in Komatsu (1963); for C. maculosus , fig. 38 in Yaginuma (1972); and for C. shinkaii , fig. 4 in Komatsu (1970)]. Males of C. daimonji sp. nov. possess a palpal tibia, which is shorter than the palpal patella, and thus can be clearly discriminated from those of C. communis [fig. 37 in Yaginuma (1972)], C. kirigaminensis [pl. 4, fig. D in Komatsu (1963)] and C. shinkaii [fig. 2-2-30- 17 in Ihara (2009a)] bearing a tibia that is longer than the patella [see also figs 2-2-30- 14–16 in Ihara (2009a)].

Material examined. Holotype: KUZ Z2753 ( Fig. 1A ), male, under rotten wood in Mt. Daimonjiyama , Sakyoku , Kyoto City, Kyoto Prefecture, Japan (35.027462°N, 135.801530°E), Kenji Matsuda ( KM), 1 November 2019 . Paratypes (in total 13 specimens collected from the type locality by KM): 6 males, KUZ Z2754 (35.027378°N, 135.801555°E), KUZ Z2755 (35.027462°N, 135.801530°E), KUZ Z2756–Z2757 (35.027280°N, 135.801641°E), KUZ Z2758 (35.026685°N, 135.801831°E), KUZ Z2759 (35.024971°N, 135.802875°E), and 4 females, KUZ Z2761 (35.027302°N, 135.801637°E), KUZ Z2762 (35.027142°N, 135.801608°E), KUZ Z2763 (35.025709°N, 135.802005°E), KUZ Z2764 (35.025709°N, 135.802005°E), 1 November 2019; 3 females,

KUZ Z2760 (35.026154°N, 135.80301°E), KUZ Z2765 (35.026370°N, 135.802903°E), KUZ Z2766 (collected near from the location of KUZ Z2765 ), 26 November 2019 ( KUZ Z2754 – Z2759 , Z2761 – Z2766 were dissected) .

Additional materials (in total 28 specimens were collect- ed from 3 locations in Kyoto, by KM): 2 males, KUZ Z2767 (35.035561ºN, 135.798191ºE), KUZ Z2768 (35.035885ºN, 135.798609ºE), and female, KUZ Z2783 (35.035507ºN, 135.798138ºE), Mt . Uryuyama, 24 October 2019; 6 males, KUZ Z2769 (35.036335ºN, 135.797853ºE), KUZ Z2770 (35.036796ºN, 135.797790ºE), KUZ Z2771 (35.036862ºN, 135.797984ºE), KUZ Z2772 – Z2773 (35.036900ºN, 135.797945ºE), KUZ Z2774 (35.037242ºN, 135.798057ºE), and 5 females, KUZ Z2784 – Z2785 (35.036597ºN, 135.797874ºE), KUZ Z2786 (35.036547ºN, 135.797793ºE), KUZ Z2787 (35.037240ºN, 135.798016ºE), KUZ Z2788 (35.037191ºN, 135.798158ºE), Mt . Uryuyama, 30 October 2019; 7 males, KUZ Z2775 (35.042871ºN, 135.797571ºE), KUZ Z2776 (35.042327ºN, 135.798311ºE), KUZ Z2777 (35.041602ºN, 135.799438ºE), KUZ Z2778 (35.041573ºN, 135.799448ºE), KUZ Z2779 (35.040904ºN, 135.799914ºE), KUZ Z2780 (35.040474ºN, 135.800204ºE), KUZ Z2781 (35.040553ºN, 135.800283ºE), and 6 females, KUZ Z2789 (35.042341ºN, 135.798351ºE), KUZ Z2790 (35.041719ºN, 135.799351ºE), KUZ Z2791 (35.041602ºN, 135.799438ºE) ,

KUZ Z2792 (35.041638ºN, 135.799287ºE), KUZ Z2793 (35.040974ºN, 135.800063ºE), KUZ Z2794 (35.040912ºN, 135.799824ºE), Mt . Uryuyama, 8 November 2019; male, KUZ Z2782 , Mt . Hieizan (35.055603ºN, 135.814328ºE), 25 November 2019 ( KUZ Z2767 – Z2771 , Z2773 – Z2789 , Z2791 – Z2794 were dissected) .

Description. Males. Measurements [KUZ Z2753 (holotype)]. Body length 6.27; carapace 3.04 long, 2.21 wide, head 1.26 wide; abdomen 2.98 long, 2.46 wide; sternum 1.52 long, 1.38 wide; labium 0.45 long, 0.45 wide. Leg formula, IV>I>II>III; length of legs (femur+patella+tibia+metatarsus+tarsus): leg I 10.24 (2.56+0.88+2.54+2.45+1.81); leg II 9.29 (2.25+0.88+2.29+2.29+1.58); leg III 8.45 (2.24+0.80+1.92+2.16+1.33); leg IV 11.11 (2.78+0.90+ 2.66+3.14+1.63).

Carapace ( Fig. 2A ): head narrow, 0.57 times as wide as thoracic region; thoracic region as high as head. Anterior median eyes smallest, approximately one-half diameter of other eyes; anterior eye row straight in frontal view; posterior eye row almost straight in dorsal view; ocular area twice as wide as long. Clypeus length 0.62 times length of median ocular area in holotype. Chelicerae geniculate, promargin of fang furrow with 3 teeth, retromargin with 4 teeth and 5 denticles (=small teeth), and basal with lateral condyle. Abdomen ( Fig. 2B ) globular.

Leg spination: Leg I: tibia p3, r3 (left) or 2 (right), v2-2-2-2; metatarsus p4 (left) or 3 (right), r3 (left) or 2 (right), v2-2- 3. Leg II: tibia p3, r3 (left) or 2 (right), v2-2-1-2; metatarsus p4, r4 (left) or 3 (right), v2-2-3.

Palp [KUZ Z2755 (paratype)] relatively slender ( Fig. 3A ). Patellar apophysis prominent on retrolateral anterior margin of patella, extended distally, slightly arched dorsally, triangular in dorsal view, distodorsal surface with 6–7 (left) or 6–8 (right) peg setae ( Fig. 3B ). Tibia slightly shorter than patella, retrolateral tibial apophysis (RTA), plate-like, occupying most of length of tibia, distal margin slightly extended ( Fig. 3B ). Cymbium slender, prolaterally unexpanded ( Fig. 3C ), 2.7 times longer than wide; 0.9 times as long as femur, 1.3 times as long as patella+tibia. Bulb elliptic ( Fig. 4A ); embolus simple, curved, originated and terminated, respectively, at ca. 11 o’clock and ca. 4 o’clock positions in ventral view ( Fig. 4A, B ); conductor simple, triangular, small ( Fig. 4B, C ).

Females. Measurements [KUZ Z2760 (paratype)]. Body length 6.02; carapace 3.14 long, 2.19 wide, head 1.47 wide; abdomen 3.28 long, 2.51 wide; sternum 1.47 long, 1.34 wide; labium 0.42 long, 0.48 wide. Legs shorter than those of male; leg formula, IV>I>II>III; length of legs (femur+patella+tibia+metatarsus+tarsus): leg I 7.96 (2.29+0.72+2.14+1.74+1.07); leg II 7.57 (2.29+0.69+ 1.82+1.65+1.12); leg III 6.69 (1.95+0.69+1.50+1.62+ 0.93); leg IV 8.51 (2.13+0.80+2.11+2.22+1.25).

Carapace ( Fig. 2C ) longer than that of male: head 0.67 times as wide as thoracic region, slightly wider than that of male. Abdomen ( Fig. 2D ) oval, slightly larger than that of male.

Leg spination. Leg I: tibia p2, v2-2-2-2; metatarsus p1, r2 (left) or 1 (right), v2-2-2. Leg II: tibia p3 (left) or 4 (right), v2-2-1-2; metatarsus p3, r2 (left) or 1 (right), v2-2-3.

Genitalia [KUZ Z2764 (paratype)]. Atrium slightly concave, located posteromedially on epigyne, anterior margin slightly curved, with two distinct copulatory openings ( Fig. 5A ). Copulatory ducts, running anterolaterally toward medial part of respective spermathecae ( Fig. 5A, C ). Paired spermathecae inverted V-shaped in ventral view; each spermatheca consisting of 3 well-defined parts, head, stalk and base ( Fig. 5B, C ): head globular, located anteromedially above epigynum, with 2 simple pores ventromedially, heads well separated from each other; stalk cylindrical, loosely coiled, with developed Bennett’s gland at junction with base; base larger than head or stalk, globular, located posterolaterally above epigynum. Pair of fertilization ducts narrow, running posteromedially ( Fig. 5B, C ).

Variation. Males. Measurements (mean±1SD, followed by ranges in parentheses; n =23, including holotype;): body length 5.26±0.42 (4.40–6.27); carapace length 2.91±0.15 (2.48–3.14), width 2.14±0.13 (1.81–2.35), head width 1.26±0.08 (0.99–1.36); abdomen length 2.45±0.27 (2.00–2.98), width 1.81±0.24 (1.33–2.46); leg I 9.40±0.54 (7.97–10.24); leg II 8.89±0.52 (7.36–9.78); leg III 7.92±0.43 (6.61–8.72); leg IV 10.07±0.57 (8.30–11.10). Leg I metatarsus with v2-2-3 spines (v2-2-1 only on right leg of KUZ Z2758). Distodorsal surface of patellar apophysis with 5–10 (left) or 5–11 (right) (usually 6, or 7) peg setae.

Females. Measurements [mean±1SD, followed by ranges in parentheses; n =19, including KUZ Z2760: for body length, abdomen length and width, n =7 (KUZ Z2760, Z2761, Z2763, Z2765, Z2783, Z2790, Z2794)]: body length 5.90±0.54 (5.36–6.43); carapace length 3.13±0.19 (2.78– 3.52), width 2.18±0.13 (2.02–2.29), head width 1.49±0.09 (1.34–1.58); abdomen length 3.37±0.39 (2.85–3.71), width 2.38±0.37 (1.82–2.70); leg I 8.15±0.39 (7.60–8.59); leg II 7.59±0.43 (6.94–8.26); leg III 6.90±0.41 (6.03–7.44); leg IV 8.89±0.49 (8.19–9.44). Leg I metatarsus with v2-2-3 spines, but sometimes with v2-2-2 spines. Spermathecal head location slightly variable, located from anterior margin to almost middle part of epigynum, but heads always separated.

Coloration. Carapace yellowish brown with reticulate olive-black markings on lateral sides of head, and with radical olive-black bands on thorax. Chelicerae, maxillae, labium and sternum yellowish brown; chelicerae deeper than others. Legs also yellowish brown, but paler than carapace, with olive black annulations. Dorsum of abdomen olive black with dull-yellowish broken chevrons ( Fig. 2 ).

Retreat. This species constructs a silken tube-like retreat, often V-shapes, with an opening at each end ( Fig. 1B ) and silk signal threads extending from each opening.

Distribution. This species appears to be restricted to a very small montane area of approximately 1.5 km 2 located on the western side of the southernmost part of Lake Biwa, Japan ( Fig. 6 ). Spiders identified as C. daimonji sp. nov. were collected from the western side of the Higashiyama- Sanjuroppo mountains. The confirmed northernmost habitat occupied by the species was located at Mt. Hieizan and the southernmost collection site was the type locality, Mt. Daimonjiyama.

DNA sequences. In total 11 sequences were determined: paratype male ( KUZ Z2755 ), six sequences, ITS-1 ( LC 529208 ; 676 bp), 28S ( LC 529207 ; 790 bp), H3 ( LC 529206 ; 328 bp), COI ( LC 529209 ; 658 bp), 12S ( LC 529211 ; 332 bp), and 16S ( LC 529210 ; 439 bp); and paratype female ( KUZ Z2764 ), five sequences, ITS-1 ( LC 529214 ; 676 bp), 28S ( LC 529213 ; 790 bp), H3 ( LC 529212 ; 328 bp), COI ( LC 529215 ; 658 bp), and 12S ( LC 529216 ; 332 bp) .

According to the nuclear ITS-1 and mitochondrial COI sequences obtained from the paratype male and paratype female, the males and females examined in this study clearly belong to the same species newly described in the present study. The ITS-1 sequences obtained from the male and female are almost concordant with each other (675/676 bp), and their COI sequences are identical.

Etymology. The specific name is derived from the type locality, Mt. Daimonjiyama. The specific name is from a Japanese word, and thus treated as indeclinable.

Remarks. Females of C. daimonji sp. nov. may be most likely to be confused with females of C. shinkaii in their spermathecal characteristics. In addition to the feature of copulatory ducts, however, females of C. daimonji sp. nov. are distinguishable from those of C. shinkaii by spermathecal heads that are separated [vs. heads contiguous; fig. 2-2- 30- 23 in Ihara (2009a)]. Although males of C. maculosus remains unknown, Ihara (2009a) suggested a possibility that C. maculosus might belong to the same species as C. communis . Therefore, it is highly possible that males of C. daimonji sp. nov. are also distinguishable from those of C. maculosus by characteristics of the palpal tibia.

In addition to the four “medium-sized” congeners, i.e., C. communis , C. kirigaminensis , C. maculosus , and C. shinkaii , males of C. daimonji sp. nov. and the other “medium-sized” C. tajimaensis Ihara and Nojima, 2004 share similar RTA characteristics, but the former can be distinguished from the latter by a triangular patella apophysis with peg setae concentrated distodorsally, an elliptic bulb, and a simple triangular conductor [vs. a trapezoidal patella apophysis with peg setae widely distributed dorsally, an almost circular bulb, and a complex hook-like conductor in C. tajimaensis ; figs 8E, 18 in Ihara and Nojima (2004)]. Although males of C. daimonji sp. nov. and the medium-sized C. tottoriensis Ihara, 1994 share the simple triangular conductor, C. daimonji sp. nov. differs from C. tottoriensis in its distally extended patellar apophysis with distodorsalpeg setae [vs. retrolaterally extended patellar apophysis with peg setae laterally in C. tottoriensis ; figs 11–13 in Ihara (1994)]. Females of C. daimonji sp. nov. can be unquestionably differentiated from females of C. tajimaensis and C. tottoriensis by their epigynal features.

Figures

Fig. 1. Cybaeus daimonji sp. nov. A, dorsal view of holotype male (KUZ Z2753); B, retreat of non-type male specimen (KUZ Z2782), from Mt. Hieizan, Kyoto, Japan, without scale. Abbreviation: OP, opening of retreat.

Fig. 2. Cybaeus daimonji sp. nov., holotype male (KUZ Z2753; A, B), and paratype female (KUZ Z2764; C, D). A, dorsal view of prosoma; B, dorsal view of abdomen; C, dorsal view of prosoma; D, dorsal view of abdomen.

Fig. 3. Cybaeus daimonji sp. nov., paratype male (KUZ Z2755), left palp. A, retrolateral view; B, dorsal view of tibia and patella; C, dorsal view of cymbium. Abbreviations: CO, conductor; PA, patellar apophysis; RTA, retrolateral tibial apophysis.

Fig. 4. Cybaeus daimonji sp. nov., paratype male (KUZ Z2755), bulb of left palp. A, ventral view; B, anteroventral view; C, ventrolateral view.Abbreviations:CO, conductor; EM, embolus.

Fig. 5. Cybaeus daimonji sp. nov., paratype female (KUZ Z2764), epigyne and spermathecae. A, ventral view; B, dorsal view; C, medial view of left part. Abbreviations: AT, atrium; BG, Bennett’s gland; BS, base of spermatheca; CD, copulatory duct; FD, fertilization duct; HS, head of spermatheca; SP, simple pore; SS, stalk of spermatheca.

Fig. 6. Map showing sampling locations in the present study. Closed circles denote the localities where Cybaeus daimonji sp. nov. samples were collected.Open circles indicate sites where specimens of C. daimonji sp. nov. were searched for but not found.