Ischnothyreus bifidus, Edward & Harvey, 2014

Edward, Karen L. & Harvey, Mark S., 2014, Australian Goblin Spiders Of The Genus Ischnothyreus (Araneae, Oonopidae), Bulletin of the American Museum of Natural History 2014 (389), pp. 1-144 : 41-48

Ischnothyreus bifidus , new species Figures 17–22 , map 3

TYPES: AUSTRALIA: Queensland: Male holotype, female allotype, and 1 female paratype from rainforest leaf litter in Mount Lewis Forest Reserve, 16 km from highway, along Mount Lewis Road , 16.57611 ° S, 145.26416 ° E (2 Apr. 2009, K. Edward and J. Waldock) deposited in QM (³ holotype: QM S95923 , PBI _ OON 00005674 ; ♀ allotype: QM S95924 , PBI _ OON 00005675 ; ♀ paratype: PBI _ OON 5640 ) .

ETYMOLOGY: The specific epithet is of the Latin bifidus , meaning ‘‘bifurcated’’ ( Brown, 1956), and refers to the distinctive bifurcated process on the anterior face of the male chelicerae of this species.

DIAGNOSIS: This species is closely related to I. hoplophorus , sp. nov., as both males possess a clypeus that is concave medially (figs. 17H, 20A, B, 23G), the anterior face of the chelicerae is modified with complex processes (figs. 19A, B, 22C, 24C), and the hyaline grooves, anterolateral corners of the carapace, endites, and the lateral edges of the labium are all heavily sclerotized (fig. 17G–I, 23G–H). Females share a unique epigynal region that consists of a heavily sclerotized platelike structure anterior to an ovoid shaped epigynal atrium (17J, 23I). Ischnothyreus bifidus , sp. nov., can be distinguished by the bifurcated anterior process on the male chelicerae (fig. 22C), and the stouter platelike sclerite of the female epigynal region, which has straighter edges (figs. 21D, 22E).

MALE (PBI_OON_0005674, figs. 17A–C, G–I, 22A–D; paratype ³: figs. 18–19, 20A– C, E, 21A–C). Total length 1.81. CEPHA- LOTHORAX: Carapace brown, broadly oval in dorsal view, pars cephalica strongly elevated in lateral view, anteriorly narrowed to between 0.5 and 0.75 times its maximum width, anterolateral corners with strongly sclerotized, triangular extension, strongly sclerotized lines extend either side of clypeus halfway to elevated portion of pars cephalica; surface of elevated portion of pars cephalica finely reticulate, sides strongly reticulate; nonmarginal pars cephalica setae dark. Clypeus margin unmodified, very strongly curved in front view, low, ALE separated from edge of carapace by less than their radius; setae dark. Eyes: ALE largest, ALE circular, PME circular, PLE oval; posterior eye row straight from above; ALE touching, ALE-PLE touching. Sternum longer than wide, pale orange, uniform; setae dark. Chelicerae, endites, and labium dark red-brown. Chelicerae slightly divergent, anterior face with distal complex projections, largest projection bifurcated (figs. 19A–C, 22C); fang with prominent basal process, broad, fluted outgrowth and large, rounded bump; setae dark. Labium elongated hexagon, not fused to sternum, anterior margin indented at middle, slightly heavier than sternum in sclerotization; with six or more setae on anterior margin. Endites anteromedian tip with one strong, toothlike projection, much more heavily sclerotized than sternum. ABDO- MEN: Ovoid; dorsum soft portions pale white. Book lung covers elliptical. Dorsal scutum brown, covering more than 3/4 of abdomen, more than 1/2 to most of abdomen width, middle surface smooth, sides smooth. Epigastric scutum small lateral sclerites present. Postepigastric scutum pale orange, covering about 1/2 of abdominal length. Dorsum, epigastric area, and postepigastric area setae dark. LEGS: Pale orange, without color pattern; patella plus tibia I shorter than carapace. Leg spination: femora: I p0-1-1; II p0-1-0; tibiae: I, II p2-2-0; v2-2-0; metatarsi: I, II p1-1-0; v1-1-0. GENITALIA: Palp proximal segments dark red-brown; embolus dark; femur shorter than trochanter, without posteriorly rounded lateral dilation; patella shorter than femur; cymbium dark redbrown; bulb dark red-brown, more than two times as long as cymbium, stout; embolic region obtusely bent, elongate, basal section broad, narrow distally, slightly curved distal tip; fine denticles present on ventral subdistal edge (fig. 21A–C, 22A, B).

FEMALE (PBI_OON 5640, figs. 17D–F, J, 22E; paratype ♀: figs. 20D, F, 21D–G). Total length 1.78. CEPHALOTHORAX: Carapace pars cephalica slightly elevated in lateral view, anteriorly narrowed to 0.49 times its maximum width or less. Clypeus straight in front view. Chelicerae, endites, and labium pale orange. ABDOMEN: Dorsal scutum covering 1/2 to 3/4 of abdomen, between 1/4 and 1/2 abdomen width. Postepigastric scutum widely hexagonal, covering about 1/3 of the abdominal length. LEGS: Leg spination: femora: I p0-1-1; II p0-1-0; tibiae: I, II p2-2- 0; v2-2-0; metatarsi: I, II p1-1-0; v1-1-0. GENITALIA: Ventral view: epigynal region with heavily sclerotized platelike structure, stout, lateral edges straight, epigynal atrium ovoid; convoluted duct thicker than apodemes (figs. 17J, 21D).

OTHER MATERIAL EXAMINED: AUS- TRALIA: Queensland: Mount Lewis Forest Reserve, Mount Lewis Road , 21–22 km from highway, rainforest, leaf litter, 16.54250 ° S, 145.28388 ° E, Apr. 2, 2009 (K. Edward and J. Waldock, QM S95925 ), 2 ³ ; Mount Lewis Forest Reserve, Mount Lewis Road , 21– 22 km from highway, rainforest, leaf litter, 16.54250 ° S, 145.28388 ° E, Apr. 2, 2009 (K. Edward and J. Waldock, QM S95926 , PBI _ OON 5559 ), 1 ³ ; Black Mountain , 17 km ESE Julatten, rainforest, moss forest litter, 1000 m, 16.65000 ° S, 145.48330 ° E, Apr. 29, 1982 (G. Monteith, D. Yeates, D. Cook, QM S12961 , PBI _OON 25809), 1 ♀ ; Carbine Tableland, Pauls Luck–Doolins Creek , 1100 m, 16.43333 ° S, 145.26666 ° E, Nov. 30, 1990 (G. Monteith, G. Thompson, D. Cook, H. Janetzki, QM S49371, PBI _ OON 22180), 1 ³ ; Carbine Uplands area, Mount Lewis Road , rainforest, leaf litter, 820 m, 16.58638 ° S, 145.29250 ° E, Apr. 1, 2009 (K. Staunton, QM S95927 , PBI _ OON 5576 ), 1 ♀ ; Carbine Uplands area, Mount Lewis Road , rainforest, leaf litter, 600 m, 16.57722 ° S, 145.30916 ° E, Apr. 1, 2009 (K. Staunton, QM S95928 , PBI _ OON 5580 ), 1 ³ ; Julatten, Mount Lewis Road , Nov. 12, 1975 (A. Walford-Huggins, ANIC, PBI _ OON 5863 ), 1 ³, 1 ♀ ; Mossman Gorge National Park , circuit track, rainforest, leaf litter, 16.47222 ° S, 145.33055 ° E, May 21, 2007 (K. Edward and K. Pitz, QM S95929 , PBI _OON 25723), 1 ³ ; Mount Demi north Peak , rainforest, 1050 m, 16.50000 ° S, 145.31670 ° E, Dec. 17, 1995, to Jan. 25, 1996 (G. Monteith, G. Thompson, Ford, QM S43388, PBI _OON 21798), 3 ³, 2 ♀ ; Mount Demi summit, 7 km SW Mossman, rainforest, 1100 m, 16.50000 ° S, 145.31670 ° E, Dec. 17, 1995, to Jan. 25, 1996 (G. Monteith, G. Thompson, Ford, QM S44688 , PBI _OON 21968), 4 ³, 3 ♀ ; Mount Demi , 7 km SW Mossman, rainforest, leaf litter, 1100 m, 16.50000 ° S, 145.31670 ° E, Oct. 29, 1983 (D. Yeates, G. Thompson, QM S16807 , PBI _OON 21531), 1 ♀ ; Mount Demi , 7 km SW Mossman, rainforest, leaf litter, 950 m, 16.50000 ° S, 145.31670 ° E, Apr. 26, 1983 (G. Monteith, D. Yeates, QM S16074 , PBI _OON 25810), 1 ³ ; Mount Demi , 7 km SW Mossman, rainforest, leaf litter, 950 m, 16.50000 ° S, 145.31670 ° E, Apr. 26, 1983 (G. Monteith, D. Yeates, QM S16122 , PBI _OON 25812), 3 ♀ ; Mount Demi , 7 km SW Mossman, rainforest, leaf litter, 1100 m, 16.50000 ° S, 145.31670 ° E, Oct. 29, 1983 (D. Yeates, G. Thompson, QM S16801 , PBI _OON 25817), 3 ³, 1 ♀ ; Mount Lewis , rainforest, leaf litter, 914 m, 16.58333 ° S, 145.28330 ° E, Sept. 4, 1983 (A. Williamson, QM S12989 , PBI _ OON 25813), 1 ♀ ; Mount Lewis Road, Windmill Creek , rainforest, 900 m, 16.56983 ° S, 145.26750 ° E, Nov. 18, 1997, to Feb. 9, 1998 (G. Monteith, D. Cook, QM S69621 , PBI _OON 21965), 1 ♀ ; Mount Lewis , 2 km N, rainforest, leaf litter, 1000 m, 16.56667 ° S, 145.26670 ° E, Sept. 9, 1981 (G. Monteith, D. Cook, QM S12962 , PBI _OON 25808), 2 ♀ ; Mount Spurgeon ( Star house), rainforest, 1100 m, 16.45500 ° S, 145.20660 ° E, Nov. 19, 1997 (D. Clyne, QM S35951 , PBI _OON 21769), 1 ♀ ; Mount Spurgeon ( Star house), rainforest, 1100 m, 16.45500 ° S, 145.20660 ° E, Nov. 19, 1997 (G. Monteith, QM S43135 , PBI _OON 21776), 1 ³ ; Mount Spurgeon ( Star house), rainforest, leaf litter, 1100 m, 16.45500 ° S, 145.20660 ° E, Nov. 20, 1997 (G. Monteith, QM S43045 , PBI _OON 21790), 1 ♀ ; Mount Spurgeon ( Star house), rainforest, leaf litter, 1100 m, 16.45500 ° S, 145.20660 ° E, Nov. 19, 1997 (G. Monteith, QM S43133 , PBI _OON 21985), 2 ♀ ; Mount Spurgeon, 2 km SE, via Mount Carbine , rainforest, leaf litter, 1100 m, 16.45000 ° S, 145.20000 ° E, Dec. 20, 1988 (G. Monteith, G. Thompson, QM S58138 , PBI _OON 22137), 1 ³, 3 ♀ ; the Bluff , 11 km W Mossman, rainforest, leaf litter, 950 m, 16.45000 ° S, 145.26670 ° E, Apr. 27, 1983 (G. Monteith, D. Yeates, QM S16072 , PBI _OON 25807), 1 ³ ; the Bluff , 11 km W Mossman, rainforest, leaf litter, 1000 m, 16.45000 ° S, 145.26670 ° E, Nov. 2, 1983 (G. Monteith, D. Yeates, G. Thompson, QM S16812 , PBI _OON 25816), 1 ♀ .

DISTRIBUTION: This species is only known from three northern subregions of the Wet Tropics Bioregion (CU, ML, and BM), in northeastern Queensland (map 3).

Figures

Fig. 17. Ischnothyreus bifidus, sp. nov. Holotype male (PBI_OON 00005674): A. habitus, dorsal view; B. habitus, ventral view; C. habitus, lateral view; G. carapace, oblique view; H. carapace, anterior view; I. sternum, ventral view. Allotype female (PBI_OON 00005675): D. habitus, dorsal view; E. habitus, ventral view; F. habitus, lateral view; J. epigynum, ventral view.

Fig. 18. Scanning electron micrographs of Ischnothyreus bifidus, sp. nov. Paratype male (PBI_OON 00021798): A. sternum, ventral view; B. mouthparts, ventral view; C. mouthparts, close-up; D. endite; E. endite, close-up of distal tip; F. endite, close-up of modified serrula.

Fig. 19. Scanning electron micrographs of Ischnothyreus bifidus, sp. nov. Paratype male (PBI_OON 00021798): A. chelicera, anterior view; B. carapace, anterior view; C. cheliceral fang, close-up of subbasal process; D. chelicera, close-up of denticles, posterior view; E. chelicera, close-up of modified setae, anterior view.

Fig. 20. Scanning electron micrographs of Ischnothyreus bifidus, sp. nov. Paratype male (PBI_OON 00021798): A. habitus, lateral view. B. carapace, lateral view. C. palpal tibia, dorsal view, showing two trichobothria. E. tarsal organ from leg I, dorsal view. Paratype female (PBI_OON 00021798): D. metatarsus III, dorsal view, showing single distal trichobothrium. F. tibia I, prolateral view, showing two spines.

Fig. 21. Scanning electron micrographs of Ischnothyreus bifidus, sp. nov. Paratype male (PBI_OON 00021798): A–C. palpal embolus, close-up. Paratype female (PBI_OON 00021798): D. epigynum, ventral view; F. spinnerets, ventral view; G. right PLS, PMS, close-up, ventral view; H. left PMS, PLS, close-up, ventral view.

Fig. 22. Ischnothyreus bifidus, sp. nov. Holotype male (PBI_OON 00005674): A. left palp, prolateral view; B. left palp, retrolateral view; C. left chelicerae, anterior view; D. left chelicerae, posterior view. Allotype female (PBI_OON 00005675): E. epigynum, ventral view. Scale lines 5 0.1 mm.