Megalopsalis leptekes, 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 : 41

Megalopsalis leptekes new species

( Figs 34 , 74–79 )

Material examined. Male holotype. Tallering Station , Western Australia, 2 September 1976, R . P. McMillan ( WAM 90 /1313) .

Paratype. 1 male, Mokine , Western Australia, 31°44'S 116°35'E, 15 July 1956, B. Y. Main, being carried by Camponotus ant ( WAM T 71949) .

Diagnosis. Megalopsalis leptekes is readily distinguished from other Megalopsalis species by its slender distitarsi III and IV without ventral brush-like setae, and also by the presence of denticulations on the anterior part of the propeltidium only.

Description. MALE (N = 2). Prosoma length 1.19, width 2.00. Anterior part of propeltidium dark orangebrown with dark brown stripe on either side of supracheliceral groove. Median and posterior parts of propeltidium and median part of mesopeltidium mottled dark brown with black patches laterally. Scattered denticles on anterior part of propeltidium, remainder of dorsal prosomal plate unarmed. Ocularium dark orange-brown, unarmed. Lateral shelves and posterolateral corners of dorsal prosomal plate orange-cream with black patches on lateral shelves. Metapeltidium and opisthosoma with broad median stripe of dark green-brown with light tan spots, laterally cream. Venter cream, with medium brown spots on coxae.

Chelicerae. Segment I 3.90–4.20, 4.98–5.25. Yellow-orange with dark brown patches on distal part of first segment and entire second segment; both segments evenly denticulate. Cheliceral fingers short; mobile finger angular crescent-shaped.

Pedipalp (figs 75–76). Femur 1.52–1.61, patella 0.83–0.84, tibia 1.03–1.05, tibia 1.99–2.10. Femur and patella orange-yellow with light brown patches, tibia cream with light brown patches, tarsus cream. Trochanter spinose dorsally and ventrally, femur with dorsal and ventral spine rows, patella with few medioventral spines. Patella with apophysis about half length of patella body (fig. 76); medial sides of patella and tibia densely setose. Microtrichia on distal half of tarsus; claw with ventral tooth-comb.

Legs. Leg I femur 3.00–3.58, patella 0.89–0.93, tibia 2.37–2.66; leg II femur 5.13–5.72, patella 1.05–1.20, tibia 4.20–4.49; leg III femur 2.59–2.96, patella 0.83–0.87, tibia 1.94–2.26; leg IV femur 4.65, patella 0.94, tibia 3.03. Orange-cream. Trochanters unarmed. Femur I with dorsal and ventral spine rows, more closely spaced ventrally; patella with ventral spine row; tibia unarmed (fig. 77). Femur II with dorsal and ventral rows of small, relatively widely-spaced spines in proximal half. Remaining segments unarmed except for few dorsal spines in proximal half of femur. Tibiae undivided; tarsi unspecialised.

Penis (figs 78–79). Bristle groups of medium length; glans distally dorsoventrally flattened. Pores shallowly recessed.

Spiracle (fig. 34). Anterior spines thick, slightly flattened, most not reticulated except cornermost spines, extending across entire spiracle; terminations broadly palmate.

Variation. The colour pattern described above refers to the holotype. The paratype has a more evenly orangebrown dorsal prosomal plate with brown patches, but this is possibly due to post-mortem bleaching.

Etymology. From the Greek adjective leptekes , fine-pointed and delicate, referring to the animal’s appearance.

Comments. The presence of lace tubercles on the lateral corner of the spiracle could not be confirmed for M. leptekes due to obscuring grit on the specimen observed.

The inclusion of M. leptekes in the genus in Megalopsalis is very poorly supported, as its position in phylogenetic analyses appeared very unstable (see ‘Results and discussion of phylogenetic analysis’). Only the equal weights analysis supported a position as sister to the remaining Megalopsalis species (see table 2). The implied weights analyses placed it either as sister to a clade including Hypomegalopsalis , Tercentenarium and the ‘Monoscutinae’ or as sister to Hypomegalopsalis tanisphyros alone with the two species then placed as sister to the clade including the taxa from Spinicrus tasmanicum to Forsteropsalis in fig. 43 (results not shown). Until the position of this species can be more firmly established, it is provisionally placed in Megalopsalis as per the results of the equal weights analysis (fig. 41).

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 74–79. Megalopsalis leptekes new species, male (all WAM 90/1313). 74. Body, dorsal view. 75. Right pedipalp, retrolateral view. 76. Patella and tibia of left pedipalp, dorsal view. 77. Left leg I, prolateral view. 78. Glans, ventral view. 79. Glans, lateral view. Scale bars for figs 74–75, 77 = 1 mm; fig. 76 = 0.5 mm; figs 78–79 = 0.1 mm.