Hypomegalopsalis tanisphyros, Taylor, 2011

Taylor, Christopher K., 2011, Revision of the genus Megalopsalis (Arachnida: Opiliones: Phalangioidea) in Australia and New Zealand and implications for phalangioid classification 2773, Zootaxa 2773 (1), pp. 1-65 : 45-47

Hypomegalopsalis tanisphyros new species

( Figs 32–33 , 86–91 )

Material examined. Male holotype. Cape Arid National Park, Mt Arid , south side nr summit, Western Australia, 33°57'45"S 123°13'01"E, 5 June 2007, M. L. Moir & M. C. Leng, under rock ( WAM T 80802; measured) .

Paratypes. 1 male, Durokoppin Nature Reserve , Western Australia, 31°25'S 117°46'E, 23 June–4 August 1987, B. Y. Main, pitfall trap ( WAM T 42176) ; 1 male, Grasspatch , Western Australia, 33°14'S 121°43'E, 6 June 1989, A. F. Longbottom, on tank, ' Clover Paddock' ( WAM 90 /1532) ; 1 male, Mt Cooke , Western Australia, 32°25'S 116°18'E, 18 September 1995, J. M. Waldock & Y. Konishi ( WAM T 71947; measured) ; 1 male, 2.5 km NE of Mt Lesueur , Western Australia, 30°10'S 115°12'E, 11 July 1989, K. Gaull et al., wandoo woodland, leaf & twig litter ( WAM 90 /1680) ; 1 male, ditto, 16 July 1989, K. Gaull, under rocks ( WAM 90 /1682; measured) ; 1 male, c. 4 km NNE of Mt Lesueur , Western Australia, 30°8'S 115°12'E, 9 July 1989, K. Gaull et al. ( WAM 90 /1675; measured) ; 1 male, Torndirrup National Park , Western Australia, 35°10'S 117°50'E, 6–13 July 1983, P. H. Dyer & J. Lyon, 4 yr burn, pitfall trap ( WAM T 72879; measured) ; 3 males, ditto, 13–20 July 1983, P. H. Dyer & J. Lyon, 4 yr burn, pitfall trap ( WAM T 72885; measured) ; 1 male, ditto, 27 July–3 August 1983, P. H. Dyer & J. Lyon, 17 year burn, pitfall trap ( WAM T 72881; measured) ; 1 male, ditto, 25 May–9 November 1983, P. H. Dyer & J. Lyon, pitfall trap ( WAM 87 /1287; measured) .

Description. MALE (N = 10). Prosoma length 0.68–0.99, width 1.10–1.48; entire body length 1.70–2.53. Anterior part of propeltidium white-tan, remainder of propeltidium and mesopeltidium light brown with iridescent silver patches; entire dorsum unarmed. Anterior corners of propeltidium silver; dark odoriferous glands readily visible through cuticle. Ocularium light brown, unarmed; very large in relation to propeltidium, nearly one-third as wide as propeltidium. Metapeltidium and opisthosoma mottled light brown medially, striped dark brown laterally, with pair of medial silver spots on each segment, tan punctures laterally. Venter white-tan with white spots on opisthosoma.

Chelicerae. Segment I 0.37–0.57, segment II 0.92–1.22. White-tan, dusted black shading dorsally on first segment; both segments unarmed, with black setae. Cheliceral fingers medium length, slender; mobile finger crescentshaped.

Pedipalps (fig. 87–88). Femur 0.84–1.44, patella 0.49–0.89, tibia 0.61–1.02, tarsus 1.12–1.80. Femur banded white-tan and dusted black; patella, tarsus and tibia each proximally medium brown, distally light tan; entire pedipalp unarmed. Patella with long rounded apophysis, approximately half to two-thirds length of patella body (fig. 88); tibia with marked mediodistal swelling; medial side of patella and tibia densely setose. Microtrichia on distal half of tarsus; claw with ventral tooth-row.

Legs. Leg I femur 2.38–2.84, patella 0.70–0.86, tibia 2.10–2.48; leg II femur 4.40–5.22, patella 0.81–1.11, tibia 4.00–4.65; leg III femur 2.35–2.78, patella 0.63–0.79, tibia 1.51–2.03; leg IV femur 3.92–5.00, patella 0.69–0.90, tibia 2.48–3.11. All segments, including trochanters, tan, unarmed. Tibia II with four or five pseudosegments; distitarsus II without ventral swellings. Tibia IV undivided; distitarsi III and IV not proximally broadened.

Penis (figs 89–91). Shaft elongate, with long tendon. Well-developed bristle groups. Glans short, triangular in ventral view, distally dorsoventrally flattened; dorsal side of glans evenly convex, without dorsolateral keel. Pores deeply recessed.

Spiracle (figs 32–33). Anterior spines thick, widely spaced, mostly lacking reticulations; terminations simple or broadly palmate. Dense array of lace tubercles at lateral corner, with reticulations from lace tubercles extending across array of reticulate lobes on posterior margin of spiracle.

Etymology. From the Greek adjective tanisphyros , slender-ankled, referring to the delicate, wispy appearance of this species.

Comments. The possibility could be raised that Hypomegalopsalis tanisphyros might represent the minor male of an unidentified Megalopsalis species , similar to the minor males previously recorded for Spinicrus and Neopantopsalis ( Taylor & Hunt 2009) . However, the characters that might be cited to associate H. tanisphyros with Megalopsalis , including the presence of an apophysis on the pedipalpal patella and the shape of the genitalia, are all apomorphies of larger clades as shown in the phylogenetic analysis above. As yet, no distinctive synapomorphies can be identified to place H. tanisphyros within Megalopsalis , and none of the analyses conducted under various parameters placed it in a monophyletic clade with Megalopsalis . Hypomegalopsalis tanisphyros can be distinguished from all known Megalopsalis species by its distinctly smaller genitalia and distinct spiracle morphology. The genitalia do not differ noticeably in size between morphs of previously identified dimorphic species (unpublished personal observations). The reticulate posterior spiracle margin of H. tanisphyros is unique among Enantiobuninae observed to date.

The significance of the large ocularium relative to propeltidium size of Hypomegalopsalis tanisphyros is uncertain. A large ocularium is also seen in various undescribed small enantiobunines of mainland Australia (unpublished observations) and seems to be correlated with particularly small body size.

Figures

FIGURES 31–34. Spiracles of Western Australian monoscutids. 31. Tercentenarium linnaei, close-up of lateral corner. 32. Hypomegalopsalis tanisphyros, entire spiracle. 33. Same, close-up of medial end of spiracle to show reticulate lobes on posterior margin. 34. Megalopsalis leptekes, close-up of spines.

FIGURES 86–91. Hypomegalopsalis tanisphyros new genus and species, male (all WAM T80802). 86. Body, dorsal view. 87. Left pedipalp, retrolateral view. 88. Patella and tibia of right pedipalp, dorsal view. 89. Penis, ventral view. 90. Glans, ventral view. 91. Glans, dorsolateral view. Scale bars for figs 86–89 = 0.5 mm; figs 90–91 = 0.1 mm.