Masirana longipalpis Komatsu, 1972

Ballarin, Francesco & Eguchi, Katsuyuki, 2022, Taxonomic notes on leptonetid spiders from the Ryukyu Archipelago with the description of two new species and the first record of the genus Longileptoneta from Japan (Araneae: Leptonetidae), Zootaxa 5213 (4), pp. 371-387 : 381-385

Masirana longipalpis Komatsu, 1972

Figs.7A–F , 8A–I , 9A–D

Masirana longipalpis Komatsu, 1972: 83 , f. 6-9 (♂ ♀).

M. longipalpis Shimojana, 1977: 347 , f. 3 (♂).

DNA barcode. GenBank accession number: OP680016 (specimen from Nisshudo cave).

Material examined. JAPAN — Okinawa Pref., Okinawa-honto Is.: Kunigami-gun: Motobu-cho: Shinzato , Abuntogama cave (アブントーガマ), 26.70075°N, 127.89205°E, 40 m a.s.l., slightly humid cave, twilight and dark zone, 4♂, 4♀ (3♂, 3♀ FBPC; 1♂, 1♀ MSNVR) , 16 Nov. 2020, F. Ballarin leg.; Kin-cho, Kin-Kannonji Temple, Nisshudo cave (HĄ洞 = Kannonji cave , ṞǠ寺Ặ乳洞) (type locality), 26.45530°N, 127.92170°E, 71 m a.s.l., large and humid cave, twilight and dark zone (temp: 20.3˚C, hum: 98.7%), 3♂, 11♀ (2♂, 6♀ FBPC; 1♂, 3♀ MNHAH; 2♀ MSNVR) , 15. V.2022, F. Ballarin & M. Araki leg.— Ishigaki-jima Is.: Ishigaki-shi: Tonoshiro, Fukubukuîzâ cave (フ クブクイーザー, AE1洞), 24.36533°N, 124.17721°E, 66 m a.s.l., long cave humid with a small creek, dark zone, 1♂ ( MNHAH), 9 Nov. 2020, F. Ballarin leg. ; same locality, 1♂, 9♀ ( FBPC), 11 Nov. 2020, F. Ballarin leg.

Type locality. Nisshu-do cave , Kin-cho, Kunigami-gun, Okinawa-honto Is., Okinawa Pref.

Diagnosis. The male of Masirana longipalpis can be easily distinguished from the male of M. suzukii sp. nov. and any other congeners by the unique shape of palp having an extremely elongated femur and tibia which are much shorter in other congeners (e.g., cf. Figs. 7A, B vs. 4A, B). The female of M. longipalpis can be easily separated by the female of other congeners, including M. suzukii sp. nov., by the large, sac-like spermathecae which are much smaller, or more rounded in other congeners (e.g., cf. Figs. 8E, F vs. 5A, B).

Redescription of male (based on specimen from Abuntogama cave). Male habitus as in Fig. 8G . Total length: 1.55; prosoma 0.69 long, 0.60 wide. ALE=0.04, PLE=0.04, PME=0.04, ALE-PLE=0, PLE-PME=0.04. Leg formula: I, IV, II, III. Leg measurements: I = 7.71 (2.45, 0.25, 2.2, 1.75, 1.06), II = 5.4 (1.81, 0.24, 1.89, 0.96, 0.50), III = 5.23 (1.49, 0.25, 1.45, 1.23, 0.81), IV =? (2.08, 0.24, -). Palp as in Fig. 7A–F . Palpal femur extremely elongated, bearing some long and robust spines on its ventral margin, smaller sparce spines on dorsal and lateral margins. Patella long; tibia extremely elongated, approximately 3 and half time longer than patella. Two apophyses (TA) on the retrodistal margin of tibia close to each other: ventral apophysis large and lanceolate; dorsal apophysis spine-like, larger at its base and ending with a sharp and long tip. Cymbium with several long spines on dorsal and distal margin, headed antero-prolaterally, ending with a long spine (= tarsal spur) similar to the others. Bulb with two transparent sclerite; median sclerite (MS) long and tread-like, twisted in middle trait; retrolateral sclerite (RS) wide and transparent, ribbon-like and wrinkled, wrapped around embolus. Embolus (E) long and robust, ending with a lightly serrated tip curved dorsally. See also Komatsu (1972) for a detailed description of the male.

Description of female (based on specimens from Abuntogama cave). Habitus as in Fig. 8H, I . Total length: 1.87; prosoma 0.80 long, 0.73 wide. Carapace uniformly yellowish. Median groove, cervical grooves and radial furrows barely visibly. Cephalic area poorly defined, slightly raised from carapace. Frontal view of cephalic area as in Fig. 8I . Six eyes all reduced, PME strongly reduced (level of eye degeneration differs among specimens examined). ALE=0.05, PLE=0.04, PME=0.03, ALE-PLE=0, PLE-PME=0.05. Chelicera, labium and maxillae uniformly yellowish. Chelicera bearing a single row of 5-6 denticles on promargin, first 2-3 proximal teeth smaller than the others; denticles on retromargin missing. Palps elongated. Sternum uniformly yellowish. Legs uniformly yellowish. Leg formula: I, IV, II, III. Leg measurements: I = 10.19 (2.81, 0.32, 3.17, 2.43, 1.46), II = 7.99 (2.18, 0.29, 2.31, 1.74, 1.47), III = 6.19 (1.73, 0.31, 1.71, 1.49, 0.95), IV = 8.24 (2.34, 0.31, 2.52, 1.95, 1.12). Opisthosoma greyish with faint pattern of slightly darker marks, wrinkled in the frontal part ( Fig. 8I ). Internal genitalia as in Fig. 8E, F . Atrium (AT) triangular with a wide base. Spermathecae stalk (SS) narrow, starting from sides of atrium, heading first frontally then turning outward and inward before reaching the top of spermathecae. Spermathecae (S) very large, sac-like, headed posteriorly.

Remarks on variation: Size variation: male (based on 3 specimens from Abuntogama cave): total length: 1.55–1.90, prosoma 0.69–0.8–long, 0.60–0.74 wide; female (based on 5 specimens from Abuntogama cave): total length: 1.56–2.1, prosoma 0.67–0.88 long, 0.63–0.77 wide.

Species with reduced eyes, depigmentation and elongation of legs and palps. The degree of troglomorphic adaptations differs among populations living in different caves or different islands. Eyes reduction varies from no reduction to totally absent (e.g., compare Figs. 8C vs. 8D and 8I, see also Shimojana 1977, pg. 348). According to Shimojana (1977, pg. 363) the populations from some caves in Okinawa-honto Is. have the highest degree of eyes reduction. Pigmentation and dorsal pattern of opisthosoma is variable, with populations totally or partially depigmented (e.g., cf. Figs. 8G, H and Figs. 9A–D ) and other having a clearer pattern (see Fig. 8D ). Specimens from different caves also show differences in thickness of embolus and its tip, ranging from thin and sharp to large and stocky (e.g., cf. Figs. 7D, F vs. 8A, B). Additional differences can be observed in the length of male palp with some populations having the femur considerably longer than tarsus + patella while in others these segments have approximately the same length (cf. Figs. 7A, B vs. fig. 8 in Komatsu 1972).

Habitat. Caves. M. longipalpis can be found in the twilight zone and, more commonly, in the humid and dark zone in the deep of the cave. It usually spins small webs in the crevices and among the rocks at the base of the cave walls or on the cave floor. The populations can be locally abundant being distributed in a large area inside the cave; in other cases the specimens occupy only a limited section of the cave where the microclimate is more favorable for this species (F. Ballarin pers. obs.).

Distribution. Endemic to the Central and Southern Ryukyus ( Fig.10 ). Widely distributed in the central and southern Ryukyus occurring in several islands: Aguni-jima Is., Hamahiga-shima Is., Ie-jima Is., Ike-shima Is., Ishigaki-jima Is., Kouri-jima Is., Kume-jima Is., Miyagi-jima Is., Okinawa-honto Is., and Tonaki-jima Is. ( Shimojana 1977; Tanikawa & Sasaki 1999) ( Fig. 10 ).

Remarks. Although M. longipalpis is relatively common and recorded from several caves in central and southern Ryukyus, during our surveys we could not find this species in some of the localities where its presence was historically documented. It is possible that the microclimate conditions of some of the caves might have changed along the years due to the increasing urbanization and consequent human activities (Y. Suzuki pers. comm.).

Figures

FIGURE 7. Male palp of Masirana longipalpis from Abutogama cave, Okinawa-honto. A palp, prolateral view; B same, retrolateral view; C tip of palp, prolateral view; D same, retrolateral view; E same, dorsal view; F same, ventral view. Scale bars: A, B = 0.2 mm; C–F = 0.1 mm.

FIGURE 8. male and female of Masirana longipalpis. A male from Nisshu-do cave, Okinawa-honto Is., tip of palp retrolateral view; B same, ventral view; C female from Nisshu-do cave, frontal view; D habitus of female from Fukubukuîzâ cave, Ishigakijima Is., dorsal view; E internal genitalia of female from Abuntogama cave, ventral view; F same, dorsal view; G habitus of male from Abuntogama cave, dorsal view; H same, habitus of female; I same, frontal view.Abbreviations:AT = atrium; E = embolus; MS = median sclerite; RS = retrolateral sclerite; S = spermathecae; SS = spermathecae stalk; TA = tibial apophyses. Scale bars: A–B = 0.1 mm, C, E, F, I = 0.2; D, G, H = 0.5 mm.

FIGURE 9. male and female of Masirana longipalpis from Okinawa in life A male from Nisshu-do cave, lateral view; B same, female; C same, female frontal view (photos by F. Ballarin); D female in its natural habitat (photo by Y. Suzuki)

FIGURE 10. Known records of Leptonetidae in the Ryukyu Archipelago and location of the related caves. Legend: pink hexagon = Longileptoneta yamasakii sp. nov.; blue dot = Masirana. suzukii sp. nov.; yellow dots = M. longipalpis; red squares = Falcileptoneta okinawaensis. Type localities of the species are highlighted with an internal black dot.