Among the 13 genera and over 100 species of halfbeaks, three genera -Dermogenys, Nomorhamphus and Hemirlzamphodonare internally fertilized and viviparous. These genera belong to a more inclusive clade, the Zenarchopterinae, that also includes Zcmarchopterus, inferred to be internally fertilized and to lay fertilized eggs, and the monotypic Tondanzchthys, also inferred to be internally fertilized. Whereas the Hemiramphidae are distributed worldwide, internally fertilized halfbeaks are restricted to Southeast Asia. Recent data from histological surveys of the gonads of both males and females as well as embryonic modifications associated with viviparity have been combined here with osteological characters in a phylogenetic analysis. Results indicate overwhelming support for a sister-group relationship between Hemirhamphodon and (Dermogenys + Noinorhamphus). Monophyly of the Dermogenys + Nomorhamphus clade is also well supported. These results confirm earlier suggestions that Dermogenys, as previously defined, is paraphyletic. Within the Dermogenys + Noinorhainphus clade, two monophyletic clades are supported: one comprises ten species including four new species (Dermogenys bruneiensis, Dermogenys robertsi, Dermogenys palawanensis and Dermogenys collettei) and the other comprises 13 species including three undescribed species (Nomorhamphus rossi, Nomorhamphus pinnimaculata and Nomorhamphus manifesta). Diagnoses for the species of Dermogenys and Nomorhamphus. as well as a natural classification for the included species, are presented.R 2001 The 1,innean Society of London ADDITIONAL KEY WORDS: viviparityinternal fertilization -Southeast Asia.-* Hemirhamphodon, were placed in a n unresolved polytomy with the monotypic genus, Tondanichthys (Fig. 1). Much of the uncertainty in generic relationships stems from the fact that sexually mature specimens of Tondanichthys are not available. Consequently, viviparity in Tondanichthys has been inferred, not observed. The purpose of this paper is to diagnose the genera of viviparous half'beaks, propose species limits for Dermogenys and Noinorhanzphus, describe seven new species, and present a phylogenetic hypothesis of the relationships among the species of Dermogenys and Noinorhainphus as well as the genera of internallyfertilized halfbeaks. TAXONOMIC HISTORYThe genus Derinogenys Kuhl I % van Hasselt in van Hasselt (1823) was first described in a letter from Java written by van Hasselt following the death of Kuhl. The genus was described for a new species, D. pusilla ,001 The 1,lnnean Societk of 1,ondon 199 00244082/01/100199 1 8 3 $35 OO/O SYSTEMATIC REVISION OF DERMOGENYS AND NOMORHAMPHUS 201Table 1. Nominal species, subspecies, and varieties of halfbeaks assigned to the genera Dermogenys and Nomorhamphus (in chronological order of description) and recognized equivalent species according t o the results of this study. New combinations and species in bold Derm ogenys D. pusilla D. pusilln

As part of an effort to characterize reproductive modifications in internally inseminating catfishes, ovaries and male reproductive systems were examined histologically in two species of auchenipterid catfishes, Trachelyopterus lucenai and T. galeatus, from southeastern Brazil. Internal insemination was documented in both species by the presence of sperm within ovaries. Although there is some variation in gross morphology of the male reproductive systems between the two species, both have four main regions: spermatogenic lobes, sperm storage regions, and secretory and storage regions of the seminal vesicle. In both species, the anterior portion of the reproductive system is spermatogenic and divided into numerous finger‐like lobes. Posterior to the spermatogenic area is the storage region of the seminal vesicle, a large median structure with a honeycomb‐like appearance. This region is consistently larger in T. lucenai. Attached to the storage region of the seminal vesicle in both species are secretory lobes comprised of tubules lined by secretory cells. These lobes in T. lucenai are small and located on the anterior aspect of the storage region of the seminal vesicle, whereas in T. galeatus the lobes are much larger and located laterally. The sperm storage regions of T. lucenai consist of two large lobes located ventral to the storage region of the seminal vesicle. Highly compact sperm packets (spermatozeugmata) fill the lumina of the ramifying tubules of these regions. Each spermatozeugma consists of elongate nuclei tightly arranged parallel to one another. In T. galeatus two distinct sperm storage regions are present. Just posterior to the spermatogenic lobes a series of small lobes serve as anterior sperm storage regions. Posterior to the secretory lobes of the seminal vesicle is a series of lobes, at the most posterior aspect of the reproductive tract, that serve as posterior sperm storage regions. Both are identical, histologically, to the sperm storage regions of T. lucenai. An absence of compact spermatozeugmata in the T. galeatus specimens may be related to variations in their sexual activity. The descriptions presented here allow for consistent terminology for comparison of regions of the male reproductive system based on presumed function. J. Morphol. 246:131–141, 2000 © 2000 Wiley‐Liss, Inc.

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