1. INTRODUCTION

Pholcidae C.L. Koch, 1850, is the sixth-largest spider family, comprising 2,024 extant species in 97 genera worldwide (World Spider Catalog 2025). Among these genera, Pholcus Walckenaer, 1805 is the largest genus with 409 species and Pholcus phungiformes-group is a highly diverse species-group containing 125 species. Most species in this species-group inhabit in mountainous regions of northern and northeastern China and the Korean Peninsula (Zhao et al. 2023;World Spider Catalog 2025). Taxonomic studies on the phungiformes- group have been actively conducted from Korea, and currently 52 species have been recorded including nomina nuda, Pholcus deokjeok Jang, Yoo, Kim & Bae, 2023 and P. gangneung Jang, Yoo, Kim & Bae, 2023 (Lee et al. 2021a, 2021b, 2024;Jang et al. 2023a, 2023b). While investigating rocky areas in mountainous mixed forests, we discovered a new species belonging to this species-group, which is described in the present study. Furthermore, the taxonomic status of P. uksuensis Kim & Ye, 2014 is revalidated, re-diagnosed, and redescribed in this paper based on specimens collected from type locality.

2. MATERIALS AND METHODS

All specimens were collected by hands and preserved in 98% ethyl alcohol and external morphology was examined under a Leica S8APO stereomicroscope (Singapore). Images were captured with a Dhyana 400DC zoom digital camera (China) mounted on a Leica S8APO and assembled using Helicon Focus 8.2.0 image stacking software (Khmelik et al. 2006). Measurements of body parts were made with an ocular micrometer and are recorded in millimeters. Internal genitalia of females were removed and treated in 10% KOH for two hours before illustration. Leg and palp measurements are shown as: Total length (femur, patella, tibia, metatarsus, tarsus). Morphological terminology follows Huber (2011). The specimens examined are deposited in the National Institute of Biological Resources (NIBR), Incheon and Konkuk University (KKU), Seoul, Korea. The following abbreviations are used in the descriptions: ALE=anterior lateral eye, AME=anterior median eye, PLE=posterior lateral eye, PME=posterior median eye, ALE-AME=distance between ALE-AME, ALEPLE= distance between ALE-PLE, AME-AME=distance between AMEs, AME-PME=distance between AME-PME, PLE-PME=distance between PLE-PME, PME-PME=distance between PMEs, L/d=length/ diameter in the leg measurement.

3. TAXONOMY

Family Pholcidae C.L. Koch, 1850

Subfamily Pholcinae C.L. Koch, 1850

Genus Pholcus Walckenaer, 1805

Diagnosis and detail description. See Huber (2011).

Type species.Aranea phalangioides Fuesslin, 1775.

Pholcus phungiformes species-group

Diagnosis and description. See Huber (2011) and Yao et al. (2021).

Pholcus osaek sp. nov. (Fig. 1)

Type material. Holotype: ♂ (KKU, #Ara_Phol_Pholcus osaek_20230920_01), Osaek-ri, Seo-myeon, Yangyanggun, Gangwon-do, Korea (38.088921°N, 128.424744°E, alt. 651 m), 20 September 2023, C.M. Jang & S.T. Kim leg. Paratypes: 2♂♂ (KKU, #Ara_Phol_Pholcus osaek_ 20230920_02-03), 1♀ (NIBR, NIBRIV0000910316), 2♀♀ (KKU, #Ara_Phol_Pholcus osaek_20230920_04- 05), same data as the holotype.

Etymology. The specific name is a noun in apposition referred to the type locality, Osaek-ri, Yangyang-gun, Gangwon-do.

Diagnosis.Pholcus osaek sp. nov. is similar to Pholcus montanusPaik, 1978 but can be distinguished from the latter by the combination of the following characteristics: Males - palpal femur without a retrolateral hump (Fig. 1I, J) versus palp femur with a low retrolateral hump (Huber 2011: 476, f. 2264), uncus rectangular (Fig. 1H) versus uncus auricle-shaped (Huber 2011: 476, f. 2263), dorso-distal apophysis small and slender with a fringed tip twisted distally (numbered 1 in Fig. 1J) versus dorso-distal apophysis large and thick with a pointed tip (Paik 1978: 118, f. 13; Huber 2011: 476, f. 2264), one spike-shaped dorsal spine (arrowed in Fig. 1I, J) versus two spine-shaped dorsal spine (Huber 2011: 476, 2263- 2265). Females - anterior arch slightly recurved versus anterior arch strongly recurved, pore plates wider than long and semicircular versus pore plates longer than wide and triangular (Fig. 1E, G) (Paik 1978: 118, f. 20; Huber 2011: 476, f. 2267).

Description. Male (holotype). Habitus as in Fig. 1A. Total length 6.12. Carapace: 1.86 long/1.91 wide. Eyes: AER 0.68, PER 0.74, ALE 0.19, AME 0.12, PLE 0.16, PME 0.17, ALE-AME 0.04, ALE-PLE contiguous, AME-AME 0.07, AME-PME 0.04, PME-PLE 0.07, PME-PME 0.26. Chelicera: 0.97 long/0.30 wide. Endite: 0.54 long/0.37 wide. Labium: 0.26 long/0.36 wide. Sternum: 0.86 long/1.20 wide. Legs: I 57.18 (14.38, 0.90, 14.50, 24.74, 2.66), II 38.62 (10.61, 0.81, 9.63, 15.77, 1.80), III 25.53 (7.38, 0.72, 6.31, 9.85, 1.27), IV 33.64 (9.77, 0.75, 8.47, 13.08, 1.57), tibia I L/d 75. Palp: 3.09 (0.65, 0.36, 0.94, -, 1.14). Abdomen: 4.00 long/1.17 wide.

Carapace pale yellowish brown, head region with pale blackish brown median and marginal bands, thoracic region with pale blackish brown radial and marginal bands (Fig. 1A). Chelicera with three apophyses; blunt proximo-lateral apophysis diagonally upward and protruding out of chelicera, rather long and pointed frontal apophysis protruding forward, and thick and pointed distal apophysis diagonally downward (Fig. 1C, D). Legs yellowish brown, retrolateral trichobothrium on tibia I at 5% proximally, tarsus I with >50 pseudosegments (only distally about 4 visible), femora and tibia with two proximal annuli and two distal annuli, metatarsi with one proximal anulus and one distal annulus, leg formula I-II-IV-III. Abdomen elliptical, pale grayish yellow with a long cardiac pattern and many black irregular spots (Fig. 1A). Palp (Fig. 1H-J): trochanter short and bulged, shorter than femur; femur without a retrolateral hump; palpal tibia with faint prolatero-ventral modification (Fig. 1H); bulb pale yellowish brown, cordiform, appendix absent (Fig. 1H, K); uncus dark blackish brown and rectangular, edge relatively smooth, pseudoappendix thick and slightly curved (Fig. 1H, K); embolus unmodified, weakly sclerotized with some semi-transparent distal fringed processes (Fig. 1H, K); procursus large and brown with dark blackish brown margin, distinct ventral knee present, two distal apophyses present, dorso-distal apophysis small, semitransparent, and slender with a fringed tip twisted distally (numbered 1 in Fig. 1H-J), prolatero-distal apophysis partly semitransparent and claw-shaped with a serrated tip (numbered 2 in Fig. 1H-J), one dorsal spine thick and spikeshaped (arrowed in Fig. 1I, J).

Female (paratype). General appearance similar to male, habitus as in Fig. 1B. Total length 5.06. Carapace: 1.67 long/1.69 wide. Eyes: AER 0.56, PER 0.60, ALE 0.16, AME 0.09, PLE 0.15, PME 0.15, AME-ALE 0.04, ALE-PLE contiguous, AME-AME 0.06, AME-PME 0.06, PME-PLE 0.04, PME-PME 0.20. Chelicera: 0.75 long/0.25 wide. Endite: 0.45 long/0.28 wide. Labium: 0.24 long/0.33 wide. Sternum: 0.75 long/1.01 wide. Legs: I 30.43 (7.63, 0.71, 7.96, 13.24, 1.89), II 21.45 (6.00, 0.56, 5.44, 8.07, 1.38), III 16.39 (4.66, 0.62, 3.90, 5.95, 1.23), IV 21.81 (6.34, 0.59, 5.47, 8.16, 1.25), tibia I L/d 47. Palp: 1.16 (0.36, 0.16, 0.24, -, 0.40). Abdomen: 3.24 long/1.65 wide. Epigynum: 0.96 wide.

Epigynum (Fig. 1E): circular, length and width approximately subequal, anterior epigynal plate sclerotized and straight posteriorly, median epigynal plate slightly depressed, posterior epigynal plate strongly procurved, knob rather long and thick with a blunt tip. Internal genitalia (Fig. 1G): anterior arch slightly recurved, pore plates large and semicircular, adjacent to the anterior arch, separated far from each other.

Variation. Tibia I in three males (Holotype and paratypes): 11.51, 10.26, 10.09 (10.62±0.68). Tibia I in three females (Paratypes): 7.69, 8.72, 8.55 (8.32±0.55). Habitat. The species was collected by hand on rock walls and under rocks in mountainous mixed forest.

Distribution. Korea (Yangyang-gun, Gangwon-do).

Pholcus uksuensis Kim & Ye, 2014 sp. revalid. (Fig. 2)

Pholcus uksuensis Kim & Ye, 2014: 52.

Pholcus woongil: Yoo et al., 2015: 13 (synonymization).

Type material. Holotype: ♀, Suseong-gu, Daegu-si, Korea (35°36ʹN-36°01ʹN, 128°21ʹE-128°46ʹE), 12 September 2012, S.H. Ye leg.. Other material examined: 3♂♂ (KKU, #Ara_Phol_Pholcus uksuensis_202309 07_01-03), 1♀ (NIBR # NIBRIV0000910313), 2♀♀ (KKU, #Ara_Phol_Pholcus uksuensis_20230907_04- 05), Uksu-gil, Suseong-gu, Daegu-si, Korea (35.816368° N, 128.706985°E, alt. 145 m), 7 September 2023, C.M. Jang & S.T. Kim leg.

Diagnosis.Pholcus uksuensis Kim & Ye, 2014 is similar to P. gajiensisSeo, 2014 and P. woongilHuber, 2011 in the shape of their genital organs and body appearance but can be distinguished from them by a combination of the following characteristics. Males of P. uksuensis can be distinguished from P. gajiensis and P. woongil by the shapes of the bulbal processes and procursus; uncus triangular with a strongly serrated distal edge (Fig. 2H), prolateral apophysis curved laterally with an angularly bent and truncated tip (numbered 2 in Fig. 2H-J), pseudo-appendix hook-shaped, long, and slender (Fig. 2H, K) versus uncus semicircular with a slightly serrated distal edge, prolateral apophysis curved laterally with a straight pointed tip, pseudo-appendix hook-shaped, short, and thick in P. gajiensis (Seo 2014: 403, f. 3A) and uncus semicircular with a smooth distal edge, prolateral apophysis curved downward with a pointed tip, pseudo-appendix Y-shaped and slender in P. woongil (Huber 2011: 476, f. 2268-2270). Females of P. uksuensis can be distinguished from P. gajiensis and P. woongil by the shape of internal genitalia: anterior epigynal plate strongly recurved, knob short and thick, pore plates small, ovoid and longitudinal (Fig. 2E-G) versus anterior epigynal plate strongly recurved, knob long and thick, pore plates small, elongated oval and slightly inclined in P. gajiensis (Seo 2014: 403, f. 3G, H) and anterior epigynal plate slightly recurved, knob short and thick, pore plates large, elongated oval and longitudinal in P. woongil (Huber 2011: 476, f. 2271, 2272, 2136, 2137).

Description. Male. Habitus as in Fig. 2A. Total length 5.37. Carapace: 1.74 long/1.80 wide. Eyes: AER 0.66, PER 0.71, ALE 0.16, AME 0.13, PLE 0.16, PME 0.14, ALE-PLE contiguous, ALE-AME 0.05, AME-AME 0.05, AME-PME 0.08, PLE-PME 0.05, PME-PME 0.27. Chelicera: 0.88 long/0.26 wide. Endite: 0.54 long/ 0.31 wide. Labium: 0.27 long/0.34 wide. Sternum: 0.83 long/1.11 wide. Legs: I 44.11 (11.31, 0.71, 11.09, 18.86, 2.14), II 29.07 (7.88, 0.68, 7.28, 11.71, 1.52), III 19.79 (5.75, 0.66, 4.69, 7.53, 1.16), IV 26.20 (7.76, 0.62, 6.51, 10.01, 1.30), tibia I L/d 66. Palp: 3.27 (0.80, 0.34, 0.96, -, 1.17). Abdomen: 3.65 long/1.60 wide.

Carapace pale reddish brown, head region with pale blackish brown median and marginal bands, thoracic region with pale blackish brown radial and marginal bands (Fig. 2A). Chelicera with three apophyses; small and blunt proximo-lateral apophysis diagonally upward and protruding out of chelicera, small, slender, and pointed frontal apophysis protruding forward, and thick and pointed distal apophysis diagonally downward (Fig. 2C, D). Legs yellowish brown, retrolateral trichobothrium on tibia I at 6% proximally, tarsus I with >32 pseudosegments (only distally about 10 visible), femora and tibia with two proximal annuli and two distal annuli, metatarsi with one proximal anulus and one distal annulus, leg formula I-II-IV-III. Abdomen elliptical, dull grayish yellow with a long cardiac pattern and many black irregular spots (Fig. 2A). Palp (Fig. 2H-J): trochanter short and bulged, shorter than femur; palpal tibia with elliptical prolatero-ventral modification (Fig. 2H); bulb pale yellowish brown, cordiform, appendix absent (Fig. 2H, K); uncus dark blackish brown, triangular, edge strongly serrated distally, truncated laterally, pseudo-appendix thick and hook-shaped (Fig. 2H, K); embolus unmodified, weakly sclerotized with some semi-transparent distal fringed processes (Fig. 2H, K); procursus large and brown with dark blackish brown margin, distinct ventral knee present, three distal apophyses present, dorso-distal apophysis claw-shaped (numbered 1 in Fig. 2H-J), prolateral apophysis curved an angularly bent and truncated tip (numbered 2 in Fig. 2H-J), prolatero-distal apophysis semitransparent and fringed (numbered 3 in Fig. 2H-J), one dorsal spine short and spine-shaped.

Female. General appearance similar to male, habitus as in Fig. 2B. Total length 4.97. Carapace: 1.54 long/1.54 wide. Eyes: AER 0.58, PER 0.64, ALE 0.17, AME 0.11, PLE 0.16, PME 0.13, ALE-PLE contiguous, ALE-AME 0.04, AME-AME 0.04, AME-PME 0.07, PLE-PME 0.06, PME-PME 0.21. Chelicera: 0.74 long/0.25 wide. Endite: 0.46 long/0.26 wide. Labium: 0.26 long/0.32 wide. Sternum: 0.71 long/1.00 wide. Legs: I 30.57 (7.57, 0.60, 7.64, 12.72, 2.04), II 20.69 (5.61, 0.56, 5.16, 8.20, 1.16), III 14.76 (4.34, 0.54, 3.60, 5.33, 0.95), IV 20.48 (6.03, 0.57, 5.12, 7.69, 1.07), tibia I L/d 50. Palp: 1.10 (0.36, 0.16, 0.19, -, 0.39). Abdomen: 3.27 long/1.75 wide. Epigynum: 0.87 wide.

Epigynum (Fig. 2E): triangular, slightly wider than long, anterior epigynal plate sclerotized and strongly recurved posteriorly, median epigynal plate strongly depressed with sclerotized lateral processes, posterior epigynal plate slightly procurved, knob short and thick with a blunt tip. Internal genitalia (Fig. 2G): anterior arch almost straight, pore plates large and elliptical, adjacent to the anterior arch, separated far from each other.

Variation. Tibia I in three examined males: 11.88, 10.31, 10.56 (10.92±0.84). Tibia I in three examined females: 8.83, 9.02, 8.67 (8.84±0.18).

Habitat. The species was collected by hand on rock walls and under rocks in a hillock mixed forest.

Distribution. Korea (Suseong-gu, Daegu-si).

Remarks.Kim and Ye (2014) described this species as new to science based on a single female specimen from Suseong-gu, Daegu-si, Korea. However, Yoo et al. (2015) regarded this species as a synonym of P. woongil based on the description in the original description and the provided illustration. In fact, the females of the Pholcus species share similar morphological and genital characteristics, making it difficult to designate a female as the holotype during the description of a new species. Therefore, the authors attempted to investigate the type locality based on the coordinates provided by Kim and Ye (2014) to examine the taxonomic identity of the species. However, the coordinates and administrative area names presented in the paper did not coincide at all. The authors investigated the administrative area mentioned in the original description and were able to collect numerous male and female specimens that shared the same morphological and genital characteristics as the female described. Considering the morphological differences mentioned in the diagnosis through revalidation, we regard P. uksuensis as a distinct species and, therefore, remove it from the synonymy P. woongil Huber, 2011.