Ambengana Millidge & Russell-Smith, 1992, a synonym of Neriene Blackwall, 1833 (Araneae, Linyphiidae)

Abstract The taxonomic status of the genus Ambengana Millidge & Russell-Smith, 1992, is revised on the basis of its original description, illustrations and re-examination of the type species. A new synonymy is proposed: Ambengana complexipalpis Millidge & Russell-Smith, 1992 (the type species of Ambengana) syn. n. with Neriene birmanica (Thorell, 1887). Therefore,the genus Ambengana Millidge & Russell-Smith, 1992 syn. n. is synonymized with Neriene Blackwall, 1833. A morphological re-description, diagnosis and comparative illustrations are provided for Neriene birmanica as well.


Introduction
Th e monotypic genus Ambengana Millidge & Russell-Smith, 1992, was erected for Ambengana complexipalpis Millidge & Russell-Smith, 1992, from Bali (Millidge & Russell-Smith 1992). Th ere has been no further report on this genus since its original description (Platnick 2010). Recently, the authors examined the linyphiid specimens collected from Yunnan Province in the southwestern China and found that some of them seemed to be A. complexipalpis. However, the structure of the copulatory organs of this species clearly indicated that this species should be considered a junior synonym of Neriene birmanica (Th orell, 1887). Th e spermathecae with spirally coiled grooves in the female, the spirally coiled terminal apophysis, and the curved and narrow embolus in the male, all indicate that this species should probably belong to the genus Neriene. Th us, the genus Ambengana should be considered a junior synonym of the genus Neriene Blackwall, 1833.
Neriene birmanica was fi rst described as Linyphia birmanica from the female (Th orell, 1887). Since then several studies have been made (Caporiacco 1935;van Helsdingen 1969;Chen et al. 1989;Chen and Gao 1990;Song et al. 1999). Among these, Caporiacco (1935) fi rst reported the male as Bathyphantes kashmiricus in Kashmir; van Helsdingen (1969) redescribed the male as Neriene kashmirica when he reclassifi ed the species of Linyphia latreille; Chen et al. (1989) fi rst reported on this species from China and synonymized N. kashmirica with N. birmanica. Th e aim of the current paper is to re-describe N. birmanica, and to illustrate with digital photos, and to propose a new synonymy.

Material and methods
Specimens were examined with an Olympus SZX16 stereomicroscope; details were studied with an Olympus BX51 compound microscope. Male palps and female epigyne were examined and illustrated after being dissected from the spider bodies. Spermathecae were cleared in boiling KOH solution to dissolve soft tissues, and the embolic divisions of male palps were excised by breaking the column (the membranous connection between the suprategulum and the radix). Photos were made with Cannon G10 digital camera (14.7 megapixels) mounted on an Olympus SZX16 dissecting microscope. Th e digital images depicting the general appearance and genital morphology are a composite of multiple images taken at diff erent focal lengths along the Z axis and assembled using the software package Helifocus 3.10. Left structures (e.g., palps, legs, etc.) are depicted unless otherwise stated. Most hairs and macrosetae are usually not depicted in the fi nal palp and epigynum images.
All measurements were obtained using an Olympus SZX16 stereomicroscope and are given in millimeters. Eye diameters are taken at the widest point. Th e total body length does not include the length of the chelicerae or spinnerets. Th e leg measurements are given in the following sequence: total (femur, patella +tibia, metatarsus, tarsus). Th e terminology used in text and fi gure legends follows van Helsdingen (1969).
All the specimens examined are deposited in the College of Life Sciences, Hubei University, China.

Diagnosis .
Tibia not fusiform, with few spines; paracymbium with narrow distal arm tapering to a sharp tip; hook-shaped tip of distal part of median apophysis curved in ventral direction; transversal and terminal sclerites never present; lateral depressions of the epigyne small and superfi cial, this species belongs to the peltata-species group ( van Helsdingen 1969). It can be distinguished from other members of the peltatagroup species by the tiny paracymbium (Fig. 4), the sword-shaped embolic tip (Figs 4,  6), the broad and short terminal apophysis with about one coil (Figs 2, 5), the translucent spot at either side of the uniquely trapeziform atrium opening, the superfi cially depressed area at either side next to lateral translucent spots (Fig. 9), and the scape forming a rounded mesal projection and spiral grooves of about two coils in the female (Figs 10, 11).
Remarks . Although we didn't examine the type speciemens of A. complexipalpis, the tiny paracymbium, the sword-shape embolic tip, broad and the short terminal apophysis, the uniquely trapeziform atrium opening shown in the original illustrations (Millidge and Russell-Smith 1992, fi gs 52-54) leave no doubts that our identifi cation is correct. Th e original illustration of the spermathecae by Millidge and Russell-Smith (1992, fi g. 55) is rather simplifi ed and shows some diff erences with the specimen of N. birmanica we have examined (cf. Fig. 11). However, such the diff erence does not aff ect our identifi cation.