Habitat use by triplefin species (Tripterygiidae) on rocky reefs in New Zealand

Habitat use and nesting sites of 12 triplefin species (Tripterygiidae) were investigated at 26 coastal and offshore rocky reef locations in north-eastern New Zealand. Within these locations, 17 broad-scale habitats and 14 fine-scale habitats were surveyed using visual transects. In terms of broad-scale habitat use, four species, Notoclinops segmentatus , Forsterygion lapillum , Forsterygion varium and Ruanoho whero showed a high similarity in distribution, irrespective of depth or habitat characteristics. The distributions of Bellapiscis lesleyae , Cryptichthys jojettae and Ruanoho decemdigitatus were relatively similar, being primarily confined to shallow habitats providing a high degree of shelter. Forsterygion flavonigrum , Forsterygion malcolmi and Notoclinops caerulepunctus were all predominantly found beyond 10 m, irrespective of habitat characteristics. Despite the majority of species using several distinct fine-scale habitats, a high degree of variation was apparent between species, with the majority of species showing extremely low overlap of fine-scale habitats used. Differences in fine-scale habitat use were not apparent when comparing the nesting sites of species. All nests were found in fine-scale habitats, presumably affording a high degree of shelter from predation and physical disturbance. Interspecific partitioning of spatial resources probably occurs by depth and microhabitat in this species assemblage in north-eastern New Zealand.     

A new species of the genus Helcogramma (Blenniiformes, Tripterygiidae) from Taiwan

A new species of triplefin fish (Blenniiformes: Tripterygiidae), Helcogramma williamsi, is described from six specimens collected from southern Taiwan. This species is well distinguished from its congeners by possessing 13 second dorsal-fin spines; third dorsal-fin rays modally 11; anal-fin rays modally 19; pored scales in lateral line 22-24; dentary pore pattern modally 5+1+5; lobate supraorbital cirrus; broad, serrated or palmate nasal cirrus; first dorsal fin lower in height than second; males with yellow mark extending from anterior tip of upper lip to anterior margin of eye and a whitish blue line extending from corner of mouth onto preopercle. Comparisons and a diagnostic key are provided for the species of Helcogramma now known from Taiwan: Helcogramma fuscipectoris, Helcogramma inclinata, Helcogramma striata, Helcogramma trigloides, and the newly recorded, Helcogramma rhinoceros.     

Gene flow,population growth and a novel substitution rate estimate in a subtidal rock specialist,the black‐faced blenny Tripterygion delaisi (Perciformes,Blennioidei, Tripterygiidae) from the Adriatic Sea

Population histories depend on the interplay between exogeneous and endogeneous factors. In marine species, phylogeographic and demographic patterns are often shaped by sea level fluctuations, water currents and dispersal ability. Using mitochondrial control region sequences (n = 120), we infer phylogeographic structure and historic population size changes of a common littoral fish species, the black‐faced blenny Tripterygion delaisi (Perciformes, Blennioidei, Tripterygiidae) from the north‐eastern Adriatic Sea. We find that Adriatic T. delaisi are differentiated from conspecific populations in the remaining Mediterranean, but display little phylogeographic structure within the Adriatic basin. The pattern is consistent with passive dispersal of planktonic larvae along cyclonic currents within the Adriatic Sea, but limited active dispersal of adults. Demographic reconstructions are consistent with recent population expansion, probably triggered by rising sea levels after the last glacial maximum (LGM). Placing the onset of population growth between the LGM and the warming of surface waters (18 000–13 000 years BP) and employing a novel expansion dating approach, we inferred a substitution rate of 2.61–3.61% per site per MY. Our study is one of only few existing investigations of the genetic structure of animals within the Adriatic basin and is the first to provide an estimate for mitochondrial control region substitution rates in blennioid fishes.     

A context analysis of bobbing and fin‐flicking in a small marine benthic fish

Most antipredator strategies increase survival of individuals by signaling to predators, by reducing the chances of being recognized as prey, or by bewildering a predator''s perception. In fish, bobbing and fin‐flicking are commonly considered as pursuit‐deterrent behaviors that signal a predator that it has been detected and thus lost its surprise‐attack advantage. Yet, very few studies assessed whether such behavioral traits are restricted to the visual presence of a predator. In this study, we used the yellow black‐headed triplefin Tripterygion delaisi to investigate the association between these behaviors and the visual exposure to (a) a black scorpionfish predator (Scorpaena porcus), (b) a stone of a size similar to that of S. porcus, (c) a conspecific, and (d) a harmless heterospecific combtooth blenny (Parablennius sanguinolentus). We used a laboratory‐controlled experiment with freshly caught fish designed to test for differences in visual cues only. Distance kept by the focal fish to each stimulus and frequency of bobbing and fin‐flicking were recorded. Triplefins kept greater distance from the stimulus compartment when a scorpionfish predator was visible. Bobbing was more frequent in the visual presence of a scorpionfish, but also shown toward the other stimuli. However, fin flicks were equally abundant across all stimuli. Both behaviors decreased in frequency over time suggesting that triplefin become gradually comfortable in a nonchanging new environment. We discuss why bobbing and fin‐flicking are not exclusive pursuit‐deterrent behaviors in this species, and propose additional nonexclusive functions such as enhancing depth perception by parallax motion (bobbing) or signaling vigilance (fin‐flicking).     

New Zealand triplefin fishes (family Tripterygiidae): contrasting population structure and mtDNA diversity within a marine species flock

Triplefin fishes (Family Tripterygiidae) dominate the New Zealand temperate coastal fish fauna in diversity (26 endemic species, 14 genera). Most species appear to have evolved as a local radiation and mostly occupy sympatric distributions throughout New Zealand. To investigate the forces driving current gene‐flow patterns and past evolutionary histories, we searched for common patterns of population genetic subdivision within eight species sampled throughout their distributions [mitchochondrial DNA (mtDNA) control region, n = 1086]. We hypothesised that common phylogeographical and population differentiation patterns would reveal past or ongoing physical processes, with differences reflecting stochastic or species‐specific processes. Striking differences between species were apparent, with strong phylogeographical structure detected in Grahamina capito and the estuarine species G. nigripenne. G. capito fell into three distinct geographically restricted lineages. G. nigripenne largely separated into northern and southern lineages (Φ_ST 0.834). Strong population structuring and isolation by distance was evident in Bellapiscis medius, B. lesleyae and Forsterygion lapillum (Φ_ST 0.686, 0.436 and 0.115, respectively). High gene flow was apparent in G. gymnota and Ruanoho whero, and F. varium. However, for the latter species, isolation was apparent with samples collected from the offshore Three Kings Islands. Overall, a strong relationship was found between habitat depth and population structure among species, and species inhabiting shallower water habitats showed lower genetic diversity with higher levels of population subdivision. High‐latitude populations generally showed low haplotype and nucleotide diversity. These data suggest that processes resulting from intraspecific differences in habitat preference, climatic histories and/or larval ecologies have subdivided populations of shallow water triplefin species.     

Ultrastructure of the glandular epidermis on the fins of male estuarine triplefins Forsterygion nigripenne

Male estuarine triplefins Forsterygion nigripenne develop enlarged fin tips during the breeding season. Using light microscopy and scanning and transmission electron microscopy the fins of males and females were compared. Tall columnar cells proliferated in the fin epidermis of males but were absent in females. The columnar cells were packed with proteinaceous granules that were bound by a double membrane. Three stages of development of columnar cells could be distinguished; the most mature expanded and ruptured to release its content. The function of the glandular epidermis is unknown but behavioural observations suggested that the secretion was applied to the egg mass and thus may protect it from infection.