Chaetodon miliaris

Abstract: Aim To investigate phylogeographic relationships, genetic connectivity and potential colonization routes for Hawaii’s endemic butterflyfishes (family Chaetodontidae). Location The Hawaiian Archipelago (central Pacific Ocean). Methods Molecular genetic analysis of mitochondrial DNA from three species of endemic Hawaiian butterflyfishes (Chaetodon multicinctus, n = 280; Chaetodon miliaris, n = 408; Chaetodon fremblii, n = 358) sampled from across the Hawaiian Archipelago was used in a suite of population genetic analyses to examine population histories and calculate coalescence times. We review a recent phylogenetic hypothesis for the Chaetodontidae and optimize ancestral distributions to nodes as a means of inferring colonization pathways to Hawaii. Results We found no evidence for population subdivisions across their ranges for any of the three endemic Hawaiian butterflyfish species (ΦST ≈ 0; P > 0.05 in each case). Coalescence analyses revealed that C. multicinctus, C. miliaris and C. fremblii date to genetic bottlenecks of c. 12 ka (95% confidence interval of τ, 0–46,732 years ago), c. 74 ka (95% confidence interval of τ, 62,918–105,699 years ago) and c. 301 ka (95% confidence interval of τ, 88,981–478,495 years ago), respectively. We found that the West Pacific appears to be the ancestral source for two of three independent colonization events to Hawaii (leading to the speciation of C. miliaris and C. fremblii). The third colonization of Hawaii (leading to the divergence of C. multicinctus) is ambiguous, but may have involved island-hopping from the South Pacific via the Line Islands. Main conclusions Our results are consistent with the growing body of data indicating that ecological specialists may be more susceptible to severe population bottlenecks during large-scale climatic variation on evolutionary time-scales. The isolation of the Hawaiian Archipelago presents challenges for colonization by even the most highly dispersive marine organisms, and routes of colonization by endemic butterflyfishes show a variable pattern, indicating that there may be several pathways, both spatially and temporally, for marine fauna to colonize Hawaii. Hawaiian endemic butterflyfishes appear to represent genetically homogeneous populations across the archipelago.

Abstract: Aspects of the reproduction and diet of the butterflyfish,Chaetodon miliaris, were studied by examining 345 individuals collected around Oahu, Hawaiian Islands. The sex ratio of this species was uniform and annual spawning activity was periodic yet seasonally protracted, extending through the winter and spring months (January–May). No lunar influence on spawning was detected. Fecundity was quadratically related to fish weight, implying an abrupt shift in the use of energy resources at the time of maturity from growth to reproduction.

Abstract: The structure and mechanism involved in jaw movements are described for an inertial high-speed suction feeding fish, Chaetodon miliaris. Jaw biomechanics were studied by (1) manipulation of live and fresh-killed specimens, (2) electrical muscle stimulation of anesthetized live specimens, (3) connective tissue severance experiments of fresh-killed and live anesthetized specimens, and (4) cine photography of live unimpaired and surgically impaired specimens. Three couplings appear to be involved in jaw opening: a levator operculi-opercular-interopercular-mandible coupling; and epaxial complex and/or hypaxial/sternohyoideus complex-hyoid apparatus-uncontracted protractor hyoideus-mandible coupling. Jaw opening, protrusion, closing of the protruded mouth, and jaw retraction occur in 60–110 msec. Jaw protrusion coincides with mandible depression during opening of the mouth. Closure of the protruded mouth is apparently the result of contractions of pars A1 and A2 of the adductor mandibulae muscle. Pars A3 and Aw may induce retraction of the jaws in the closed-protruded state. Jaw closure in the retracted, nonprotruded state may involve all branches of the adductor mandibulae. The importance of these findings is discussed in light of previous studies as are some proposed functions of jaw protrusion in this species.

Abstract: Summary Length–weight and length–length relationships are presented for three species of butterflyfish endemic to the Hawaiian Islands and Johnston Atoll. From specimens collected within the Papahānaumokuākea Marine National Monument (PMNM), the weight–length relationships were determined for Chaetodon fremblii as W = 0.029SL3.17, Chaetodon miliaris as W = 0.042 SL3.00, and Chaetodon multicinctus as W = 0.029SL3.19 where weight, W, is reported in grams and standard length, SL, in centimeters. Length-frequency data and equations to calculate total length from standard length are also presented.