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| Cirripectes matatakaro from Kiritimati Island, Kiribati, Line Islands. Hoban & Williams, 2020 Photographed by D. Rolla. |
Abstract
Included among the currently recognized 23 species of combtooth blennies of the genus Cirripectes (Blenniiformes: Blenniidae) of the Indo-Pacific are the Hawaiian endemic C. vanderbilti, and the widespread C. variolosus. During the course of a phylogeographic study of these species, a third species was detected, herein described as Cirripectes matatakaro. The new species is distinguished primarily by the configuration of the pore structures posterior to the lateral centers of the transverse row of nuchal cirri in addition to 12 meristic characters and nine morphometric characters documented across 72 specimens and ∼4.2% divergence in mtDNA cytochrome oxidase subunit I. The new species is currently known only from the Marquesas, Gambier, Pitcairns, Tuamotus, and Australs in the South Pacific, and the Northern Line Islands and possibly Johnston Atoll south of Hawaiʻi. Previous researchers speculated that the geographically widespread C. variolosus was included in an unresolved trichotomy with the Hawaiian endemic and other species based on a morphological phylogeny. Our molecular-phylogenetic analysis resolves many of the previously unresolved relationships within the genus and reveals C. matatakaro as the sister lineage to the Hawaiian C. vanderbilti. The restricted geographic distribution of Cirripectes matatakaro combines with its status as sister to C. vanderbilti to indicate a southern pathway of colonization into Hawaiʻi.
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| Figure 7: Photographs of freshly dead Cirripectes matatakaro sp. nov. specimens showing live coloration. (A) 60 mm SL adult male holotype (USNM 423364, Austral Islands). (B) 60 mm SL adult female paratype (USNM 409139, Marquesas Islands). Photographed by Jeffrey T. Williams, Smithsonian Institution. |
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| Figure 8: Freshly dead Cirripectes matatakaro sp. nov. 43 mm SL adult male paratype (BPBM 16928, Pitcairn Island). Photographed by John E. Randall (Smithsonian Institution National Museum of Natural History, 1970). |
Cirripectes matatakaro sp. nov
Suspiria Blenny
Diagnosis: Cirripectes matatakaro can be distinguished from congeners by the following combination of characters: (1) male genital papilla with two widely separated slender filaments to either side of the gonopore, type I sensu Williams (1988) (Fig. 3A); (2) nuchal cirri divided into two, rarely three or four, groups always slightly separated dorsally on nape with bases swollen beneath ventralmost cirri on either side; (3) overall shape of the transverse row of nuchal cirri modally type I (Fig. 4A) and sometimes type II (Fig. 4B) (types C and G sensu Williams), with 32–38 independently based cirri; (4) dorsal separation in row of nuchal cirri 0.1–0.7 mm (median width 0.3 mm); (5) where interrupted laterally, lateral breaks in row of nuchal cirri 0–0.4 mm in width (median width 0 mm); (6) sensory pore structure directly posterior to lateral center of row of nuchal cirri type I (Fig. 4C), posterior and parallel to row of nuchal cirri, does not visibly penetrate through break (where present); (7) 0–6 distinct LLT; (8) head coloration in life commonly bright reddish orange on upper section with bright red spots and/or slashes extending dorsally and posteriorly from the snout; (9) outer ring of iris bright orange-red in life.
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| Figure 10: Underwater photograph of likely female Cirripectes matatakaro sp. nov. Photographed by D. Rolla at Kiritimati Island, Kiribati, Line Islands. |
Etymology: The specific epithet is i-Kiribati, consisting of the words “mata” (eye) and “takaro” (ember/burning coal) and refers to the large, eager-seeming eyes and the reminiscence of the red slashes on the face to smoldering embers or burning coals. The species was named in the i-Kiribati language to honor the people and culture of Kiribati, where the first author first encountered and collected the new species. The common name Suspiria Blenny is in reference to the color palette of the 1977 Dario Argento film of the same name.
Remarks: Cirripectes matatakaro is noteworthy in habitat use for a member of this genus. In the southern portion of its range, from Pitcairn to the Austral Islands, C. matatakaro has primarily been collected from >20m depth, deeper than other known Cirripectes species. This may be a unique habitat exploited by this species, although in the Line Islands (Kiritimati and Palmyra) we collected it from the shallow (<5 m) oceanic forereef habitat more typically inhabited by congeners. Williams (1988) remarked that certain “problematical” specimens of C. variolosus, which were collected from deeper reefs in the Pitcairn Islands exhibited a reddish-orange head, and he speculated that the coloration might be an artifact of their depth of occurrence. Upon reexamination of that material, we determined those specimens to be the new species. Thus, the reddish color is more likely to be a property of the species rather than a product of its habitat, as individuals from Kiritimati and Palmyra show similar color patterns. We have not seen consistent evidence of sexual dichromatism, however one individual photographed in situ at Kiritimati Island had a distinctively light grey body coloration that is sometimes seen in females of other species of Cirripectes (Fig. 10).
Conclusions:
The Hawaiian Archipelago is one of the most isolated island groups in the world and the origin of its marine species is an important question. Hawaiian biodiversity is thought to arrive either from the Western Pacific, via the Kuroshio Current, or from the south, via dispersal from Johnston Atoll or the Line Islands. The Scarface Blenny Cirripectes vanderbilti, which is endemic to the Hawaiian Islands and Johnston Atoll, was long thought to be closely related to the widespread C. variolosus. Through genetic and taxonomic analyses, we showed that the sister species to C. vanderbilti is a new species, C. matatakaro, that is known from the Line Islands south to the Marquesas, Pitcairn, Tuamotus, Gambier, and Austral Islands. Its limited distribution throughout islands to the south of Hawaiʻi and its status as sister to the Hawaiian endemic strongly indicates a southern route-to-colonization, although the lack of specimens from Johnston Atoll leaves the specific pathway an open question.
Our work, and other recent studies, shows that the genus Cirripectes contains more cryptic diversity than previously thought. These results highlight the importance of ongoing genetic and biodiversity inventories on coral reefs, particularly as these habitats are increasingly under threat. Investigation of often-overlooked groups such as cryptobenthic reef fishes may uncover interesting evolutionary patterns, as in the case of Cirripectes, where widespread taxa are found to comprise multiple cryptic lineages with adjunct geographic ranges, suggesting parapatry as well as allopatry as evolutionary mechanisms in fishes. Our work also showcases the value of natural history collections to taxonomic and biogeographic research. Despite low sample numbers and narrow geographic coverage for our phylogeographic/genetic analyses, we were able to use museum specimens to make inferences about species range sizes and historic routes to colonization. Combtooth blennies and other cryptobenthic fishes often utilize vulnerable, high-energy surge zone habitats and may be underrepresented in museum collections as these habitats are difficult and/or dangerous to sample. As mass coral bleaching events and habitat degradation increase worldwide, we risk extensive biodiversity loss before we are even aware of its existence.
Mykle L. Hoban and Jeffrey T. Williams. 2020. Cirripectes matatakaro, A New Species of Combtooth Blenny from the Central Pacific, illuminates the Origins of the Hawaiian Fish Fauna. PeerJ. 8:e8852. DOI: 10.7717/peerj.8852
