Borneo boasts plenty of spectacular balitorids. Some of them possess a secondary rostrum among them Gastromyzon extrorsus occurring in short westward running streams draining Crocker Range west face, Sabah, Borneo, Malaysia.
The Borneo Suckers: Revision of the Torrent Loaches of Borneo (Balitoridae: Gastromyzon, Neogastromyzon)
The author Tan Heok Hui holds a doctorate degree in fish systematics obtained from the National University of Singapore in 2003. His doctorate thesis has been published in form of this book. It is a taxonomic monograph about fishes of the balitorid genera Gastromyzon, Hypergastromyzon and Neogastromyzon - all of them endemic to Borneo.
Although the book is split into the chapters Introduction, Biogeographic Observations, Ecological Observations, Economic Value, Bornean Endemic Genera and Species, Material and Methods, and Taxonomy valuable information about ecology resp. biology of these fascinating balitorids are scarce.
Chapter Biogeographic Observations; well researched and written chapter, which features the balitorid diversity in all Bornean water systems as well as some valuable abiotic factors for their livelihood. The Kapuas basin in Indonesian Kalimantan Barat has been identified to be the richest source for balitorids on Borneo boasting five Gastromyzon, one Neogastromyzon and one Hypergastromyzon species. A comprehensive table shows the distribution in water systems of all species dealt with in this book. The good impression of this chapter is spoilt when the author attemps to describe the differences between the concepts of cryptospecies and species pairs in the subchapter Cryptospecies and species pairs. He is unable to convey the basics of these two concepts to the reader.
Chapter Ecological Observations; this chapter is unfortunately very scarce. All information provided are citations collected from various authors. There is virtually no own oberservation supplemented. What a pity! Disappointing! However, the reader must bear in mind that this book is a work about systematics, not about ecology. But can serious systematician do it without the knowledge of the species’ ecology?
Chapter Economic Value; the author seem to be aquarists as many of us. Some paper cited here are typical aquarium literature. A professional aquarium fish collector has been interrogated to gain more knowledge about the aquarium fish trade. He revealed that he intentionally introduced ‘alien’ balitorids into a basin hoping they will reproduce and could harvest them in the future.
Chapter Bornean Endemic Genera and Species; one can find local recipes for cooking falt loaches. Locals seem to gut and boil them. The fish is salten and eaten mainly with rice, the boiling water is drunk as a soup. Besides, there is a small list of vernaculars. Again, the vernaculars are cited from another work. Overall a disappointing chapter.
Chapter Material and Methods; now the reader finds what it is all about; systematics. This chapter definitely belongs to the strengths of this book. It seems that the author is fully dedicated to the topic and knows what he talks about. There are excellent monochrome sketches and photographs showing the peculiarities of the species dealt with. Some of these peculiarities have not been explained in public literature hitherto. All explanations and definitions the author took seem to make sense. I just disagree with a small detail; the author measures head width at the origin of the pectoral fins. For Bornean species this might work, but when it comes to certain Chinese balitorids it fails. In Beaufortia cyclica the origin of the pectoral fins is located at the mouth, close to the tip of the rostrum. Measuring a head width at that position is meaningless. In my opinion a head width at the center of th eyes works much better.
Chapter Taxonomy; the author saved the best for last. He re-described the type material of the 21 known Gastromyzon species. In addition he described 15 species new to science in the genus Gastromyzon. Of these 36 species in total 26 are illustrated in color plates at the end of the chapter. Besides Gastromyzon, the author reviewed the genus Neogastromyzon including the description of four new species and gives a brief diagnosis of Hypergastromyzon. The chapter starts with the key of all species of Gastromyzon, Neogastromyzon and Hypergastromyzon known to occur on Borneo following by a definition of 11 artificial groups for Gastromyzon species. Each species is described in details. The topic field notes provides information about the habitat of the species (ecology). Unfortunately the bulk of the descriptions are lacking these notes or the notes are restricted to one lapidary sentence. Another drawback is that in some cases the characters in the species diagnosis are not congruent with the characters used in the key to the species. For e. g. the species Gastromyzon extrorsus is characterized by a broad head (26.6-28.0% of SL) in the key but not in the diagnosis.
If you are a balitorids nut you must have this book. There are interesting information about Bornean balitorid zoo-geographics and taxonomy. A handful of beautiful species are described in this book. Strong buy!
