A new cottid species, Icelus sekii (Perciformes: Cottoidei) from Hokkaido, Japan

A new cottid species, Icelus sekii, is described on the basis of six specimens collected from off Rausu and Urakawa, Hokkaido Island, Japan. This species is distinguished from its congeners by the following combination of characters: supraocular and parietal spines absent; nuchal spine obscure; uppermost preopercular spine unbranched; no scales between dorsal scale row and lateral-line scale row, and no scales below lateral-line scale row; supraocular, parietal, and nuchal cirri present; five dark brown saddles dorsolaterally; anal-fin rays 13; pectoral-fin rays 15; vertebrae 12 + 24~5 = 36~7. Icelus sekii can be mature at the smallest size among the species of Icelus. As a secondary sexual character, the male holotype has unique ensiform flaps on the distal tips of the first dorsal fin

Rhamphocottus nagaakii (Cottoidea : Rhamphocottidae), a new species of grunt sculpin from the northwestern Pacific, with notes on the phylogeography of the genus Rhamphocottus

A new species of grunt sculpin, Rhamphocottus nagaakii inhabiting the northwestern Pacific, previously identified as Rhamphocottus richardsonii Gunther 1874, is described based on genetic evidence and morphological differences. The new species can be distinguished based on morphometric characters related to the head, including head length [45.3-54.6% of standard length (SL)], postorbital head length (18.8-25.5% SL) and the length of pectoral-fin base (15.8-20.7% SL), which are smaller than in R. richardsonii (53.6-60.5% SL, 26.2-31.7% SL, and 19.5-25.2% SL, respectively). Genetic differences between two species markedly exceed levels for intra-specific differences. Rhamphocottus nagaakii is considered to have arisen from a common ancestor of the two species, which probably inhabited somewhere the North Pacific Rim around the Aleutian Archipelago. During a period of cooling in the Pliocene or the Miocene, R. nagaakii and R. richardsonii became separated to the southern regions of the northwestern and northeastern Pacific, and subsequently underwent speciation

Effect of Ultrasonic Vibration on Micro Grooving

This paper deals with the micro cutting method to fulfill the current demand for higher precision and efficiency in micro machining. In this work, a micro end mill with a diameter of 20 μm is fabricated and its performance is evaluated in grooving under the condition of with or without ultrasonic vibration assistance. Here, the machining characteristic is clarified and further its machining mechanism is also considered. Experimental results showed that micro grooving conducted with the assistance of ultrasonic vibration proven to be an effective method for burr removal

Characteristics of Grooving by Micro End Mills with Various Tool Shapes and Approach to Their Optimal Shape

Recently micro machining in many fields needs to be operated accurately and efficiently. The present paper deals with the fabrication of micro end mills with a diameter of 20 μm by precision grinding and their application to the micro grooving on duralumin in order to realize an accurate and efficient micro end milling. Micro end mills with various tool shapes are fabricated and their grooving tests are carried out. The characteristics of micro end mill in grooving test are clarified and the approach for its optimal tool shape is tested