aqua International Journal 11(3)
Volume 11, Issue 3 – September 2006
Volume 11, Issue 3 – September 2006
Wouter Holleman: Fishes of the Helcogramma steinitzi species group (Blennioidei: Tripterygiidae) from the Indian Ocean, with descriptions of two new species, pp. 89-104
Three species of Helcogramma from the Indian Ocean that form a monophyletic group are recognised: Helcogramma steinitzi Clark (Red Sea and Gulf of Oman), H. rosea n. sp. (Andaman Sea and Sri Lanka) and H. microstigma n. sp. (East African coast and adjacent islands). Helcogramma microstigma is distinguished from the other two species by a head profile of 67°-72° (about 60° in the other two species) and a long orbital cirrus (short and triangular in the other two species) and clusters of micromelanophores on the dorsum at the ends of the second and third dorsal fins of mature males (absent in the other two species). Helcogramma steinitzi has melanophores only on the distal half of the anal fin (in the other two species melanophores cover the entire fin) and a narrow interorbital (16.6 in head length). Helcogramma rosea has a sharper head profile of 56°-62°, similar to that of H. steinitzi, but is distinguished from it by anal fin pigmentation, a wider interorbital (about 15 in head length) and smaller size (maximum SL 33 mm cf. 47 mm for H. steinitzi). The three species in the group share a number of putative synapomorphies including very close-set first two dorsal-fin spines and densely packed micromelanophores on the membrane between these first two spines of both males and females. The close similarity of the species, their distribution, and comparisons to other tripterygiid species groups are discussed.
John E. Randall: Three new species of the gobiid fish genus Tryssogobius from the western and South Pacific, pp. 105-116
The small fishes of the gobiid genus Tryssogobius Larson & Hoese, 2001 are represented by the following five species: T. colini Larson & Hoese, 2001 from Indonesia, Malaysia, and Papua New Guinea in 27-41 m; T. flavolineatus n. sp. from New Guinea and Indonesia in 28-82 m; T. longipes Larson & Hoese, 2001 from Indonesia and Papua New Guinea in 19.5-27 m; T. nigrolineatus n. sp. from Fiji from 73-110 m; and T. quinquespinus n. sp. from Papua New Guinea in 27 m. They are distinguished primarily by fin-ray counts and in colour.
Ivan Sazima: Theatrical frogs and crafty snakes: predation of visually-signalling frogs by tail-luring and ambushing pitvipers, pp. 117-124
A species of torrent frog (Hylodes asper) is a common prey to two species of pit viper (Bothrops jararacussu and B. jararaca) in coastal streams of the Atlantic forest in south-east Brazil. The diurnally active frogs are cryptically coloured against the rocky background and the males advertise their presence with visual signals. When a displaying male extends and moves a hind limb, the whitish digits and toe fringes stand out against the background. Moreover, the frogs have acute vision and are able to spot a moving prey at up to 2.8 m. The pit vipers are habitually nocturnal; nonetheless juveniles of the two species forage for frogs by day on the stream banks. The frogs are ambushed or lured by wiggling movements of the tail used by the pit vipers to attract ectothermic prey. Juvenile pit vipers often have whitish or yellowish tail tips that stand out against their camouflage colours while coiled up in ambush. I suggest that the pit vipers’ tactic of luring with the tail benefits from the visual signalling used by the frogs, since the frogs tend to react to the movement of light-coloured extremities. Similar prey-predator relationships may occur on tropical streams that harbour visual-signalling diurnal frogs and vipers that forage for frogs and lure them with coloured tail tips.
Gerald R. Allen and Mark V. Erdmann: Cirrhilabrus cenderawasih, a new wrasse (Pisces: Labridae) from Papua, Indonesia, pp. 125-131
Cirrhilabrus cenderawasih is described from seven specimens, 38.9-65.1 mm SL, collected at Cenderawasih Bay, Papua, Indonesia. It is closely related to C. walindi from Papua New Guinea and the Solomon Islands, but differs with regards to male colour pattern, particularly the number, shape and position of large dark blotches along the back and adjacent dorsal fin. There are 4-5, irregularly rounded blotches that extend well onto the back in C. cenderawasih in contrast to only two, rectangular blotches for C. walindi that are primarily positioned on the dorsal fin. It is hypothesized that these species arose from a common ancestor that was once widely distributed along the northern margin of the New Guinea-Australian Plate, but land and current barriers formed over the past few million years have facilitated isolation and eventual speciation in the Cenderawasih Bay population.
|Dimensions||26.6 × 20.3 × 0.3 cm|
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