 |
| Flexor incus
Conway, Stewart & Summers, 2018
|
Abstract
Flexor incus, new genus and species, is described from 15 specimens (14.0–27.2 mm SL) collected from shallow (0–9 meters) intertidal and sub-tidal waters of the Rangitāhua Kermadec Islands, New Zealand. The new taxon is distinguished from all other members of the Gobiesocidae by a combination of characters, including a heterodont dentition comprising both conical and distinct incisiviform teeth that are laterally compressed with a strongly recurved cusp, an oval-shaped opening between premaxillae, a double adhesive disc with a well-developed articulation between basipterygia and ventral postcleithra, and many reductions in the cephalic lateral line canal system. The new taxon is tentatively placed within the subfamily Diplocrepinae but shares a number of characteristics of the oral jaws and the adhesive disc skeleton with certain members of the Aspasminae and Diademichthyinae.
Keywords: Acanthomorpha, Aspasminae, Diademichthyinae, Diplocrepinae, taxonomy
 |
| Figure 1. Flexor incus, NMNZ P.060717, holotype, 20.8 mm SL; New Zealand, Kermadec Islands, Raoul Island. |
 |
| Figure 2. Flexor incus, Te konui Point, Raoul Island, Kermadec Islands, 28 meters depth, photographed by R. Robinson (www.depth.co.nz) during the 2011 Kermadec Islands Biodiscovery Expedition, a project led by the Auckland Museum. Specimen not retained. |
Systematics
Flexor gen. n.
Diagnosis: A genus of the Gobiesocidae differing from all other genera by a combination of characters, including: head and anteriormost part of body similar in width; a relatively elongate body with a small, double adhesive disc located beneath anteriormost part of body; an oval-shaped gap between premaxillae formed by a semicircular indentation along medial edge of premaxilla; premaxilla with a single row of teeth, comprising 2–3 peg-like, conical teeth anteriorly at, and adjacent to, symphysis and 10–12 strongly laterally compressed, incisiviform teeth with strongly recurved cusp, along outer margin of bone; lower jaw with a single row of 14–16 small, conical teeth with sharply pointed and slightly recurved tip; posterior tip of basipterygium expanded and articulating with anteromedial edge of ventral postcleithrum via a shallow concave facet; mandibular portion of preoperculo-mandibular lateral line canal absent; lachrymal canal with two pores; upper and lower lip simple, uniform in thickness along jaw margin.
Etymology: New Latin, anatomical term for muscles, from the Latin flexus, past participle of flectere, to bend. In reference to the great flexibility of clingfishes, many of which have the ability to bend the body so that the tail end comes to lie close to the head. Masculine.
Type species: Flexor incus, new species
Aspasmogaster sp.: Stewart 2015: 1539, 1544;
Trnski et al. 2015: 473, 476, Table 1.
Etymology. Incus is the Latin word for anvil, in reference to the anvil-like outline of Raoul Island, the largest island in the Kermadec archipelago and type locality of the new species. A noun in apposition.
 |
| Figure 11. Distribution of Flexor incus. Type locality in red. |
Distribution and habitat. Known to date only from intertidal and subtidal waters of the Kermadec Islands (Figure 11), including Raoul Island (type locality) and L’Esperance Rock. The majority of available specimens were collected from rock pools and from shallower subtidal areas (down to 9 meters) over rock and coral rubble substrates using ichthyocides (Stewart 2015). However, a single specimen of the new species has been observed (and photographed) at 28 meters in depth (Figure 2).
Kevin W. Conway, Andrew L. Stewart and Adam P. Summers. 2018. A New Genus and Species of Clingfish from the Rangitāhua Kermadec Islands of New Zealand (Teleostei, Gobiesocidae). ZooKeys. 786: 75-104. DOI: 10.3897/zookeys.786.28539
