# Evidence of cryptic species in the blenniid Cirripectes alboapicalis species complex, with zoogeographic implications for the South Pacific

Erwan Delrieu-Trottin, Libby Liggins, Thomas Trnski, Jeffrey T Williams, Valentina Neglia, Cristian Rapu-Edmunds, Serge Planes, Pablo Saenz-Agudelo

<figure><img src="image_1.png" /></figure>

## To cite this version:

Erwan Delrieu-Trottin, Libby Liggins, Thomas Trnski, Jeffrey T Williams, Valentina Neglia, et al. Evidence of cryptic species in the blenniid Cirripectes alboapicalis species complex, with zoogeographic implications for the South Pacific. Zookeys, 2018, 810, pp.127-138. 10.3897/zookeys.810.28887. hal-04905720

HAL Id: hal-04905720

https://hal.science/hal-04905720v1

Submitted on 31 Jan 2025

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# Evidence of cryptic species in the blenniid *Cirripectes alboapicalis* species complex, with zoogeographic implications for the South Pacific

Erwan Delrieu-Trottin¹, Libby Liggins²,³, Thomas Trnski³, Jeffrey T. Williams⁴, Valentina Neglia¹, Cristian Rapu-Edmunds⁵, Serge Planes⁶,⁷, Pablo Saenz-Agudelo¹

¹ Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
² Institute of Natural and Mathematical Sciences, Massey University, Auckland, New Zealand
³ Auckland War Memorial Museum, Tamaki Paenga Hira, Auckland, New Zealand
⁴ Division of Fishes, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Suitland, MD USA
⁵ Mike Rapu Diving Center, Caleta Hanga Roa O’tai, Isla de Pascua, Chile
⁶ PSL Research University: EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, Perpignan Cedex, France
⁷ Laboratoire d'Excellence "CORAIL", Papetoai, Moorea, French Polynesia

Corresponding author: Erwan Delrieu-Trottin (erwan.delrieu.trottin@gmail.com)

Academic editor: D. Morgan | Received 5 August 2018 | Accepted 9 October 2018 | Published 20 December 2018

http://zoobank.org/E4E66F6A-17C2-4A91-B528-BD940A50045B

**Citation:** Delrieu-Trottin E, Liggins L, Trnski T, Williams JT, Neglia V, Rapu-Edmunds C, Planes S, Saenz-Agudelo P (2018) Evidence of cryptic species in the blenniid *Cirripectes alboapicalis* species complex, with zoogeographic implications for the South Pacific. ZooKeys 810: 127–138. https://doi.org/10.3897/zookeys.810.28887

## Abstract

Rapa Nui, commonly known as Easter Island (Chile), is one of the most isolated tropical islands of the Pacific Ocean. The island location of Rapa Nui makes it the easternmost point of the geographic ranges for many western Pacific fish species that are restricted to the subtropical islands south of 20°S latitude. The blenniid fish species *Cirripectes alboapicalis* has been thought to have one of the most extensive geographic distribution ranges among these southern subtropical fish species, extending from the southern Great Barrier Reef to Rapa Nui. A phylogenetic analysis was conducted to determine the taxonomic status of the species. The results provide genetic evidence that suggests that this formerly South Pacific-wide species comprises at least three cryptic species with allopatric geographic distributions. The analyses reveal the geographic distributions of these clades and their genetic relationships with each other, and with other species within the genus *Cirripectes*. The processes that culminated in the current geographic distribution of this species complex and the zoogeographic implications of this finding for the South Pacific region are discussed.
Keywords

Austral Islands, Blenniidae, cryptic species, cytochrome oxidase I, Easter Island, endemism, French Polynesia, Gambier Islands, Kermadec Islands, mtDNA, Phylogeny, Rangitāhua, Rapa Nui

Introduction

The Indo-Malay-Philippines Archipelago is the hotspot of species richness for reef
fishes in the Indo-Pacific region (Carpenter and Springer 2005), a richness that tends
to decline with distance from this hotspot (Bellwood and Wainwright 2002; Connol-
ly et al. 2003; Allen 2008; Briggs 2009). Accordingly, the high latitude and remote
island of Rapa Nui (Easter Island, Chile), located on the eastern border of the South
Pacific region, hosts one of the lowest levels of species richness reported for coral
reef fishes, with only 139 shore fish species (Randall 1976; Randall and Cea 2011;
Friedlander et al. 2013). The isolation of Rapa Nui has also resulted in a high pro-
portion of endemic species (almost 22 %) (Randall and Cea 2011). The location of
Rapa Nui (south of 20°S latitude) makes it the easternmost point of the geographic
ranges for many subtropical Pacific fish species. These species are often either narrow-
range endemics restricted to only a couple of subtropical islands of the south Pacific
(e.g., *Itycirrhitus wilhelmi* found only around Rapa Nui and Pitcairn Islands), or they
may be widespread and occur at most of the subtropical islands south of 20°S lati-
tude from the southern Great Barrier Reef to Rapa Nui (e.g., *Anampses femininus*).
However, understanding the contribution of other South Pacific locations, and Rapa
Nui's own isolation, to its fish species richness and endemism is not easily answered
through examination of species ranges alone. Phylogenetic analysis can provide com-
plementary information regarding the evolutionary history of species that, together
with their geographic distribution, can shed light on the origin and distribution of
regional species richness.

The blenniid fish species *Cirripectes alboapicalis* (Ogilby 1899) has apparently one
of the most extensive geographic distributional ranges among the southern subtropi-
cal fish species, extending from the southern Great Barrier Reef (type locality at Lord
Howe Island) eastwards to Rapa Nui (Williams 1988). The taxonomic history of the
Rapa Nui population of this species has not been straightforward; the first specimens
collected were described as a subspecies (*Cirripectes variolosus patuki* (De Buen 1963))
and later elevated to the species level by Springer (1970). Williams (1988), co-author
of the present study, placed the Rapa Nui endemic *C. patuki* in the synonymy of *C.
alboapicalis* in his revision of the genus *Cirripectes*. The development of analytical
techniques in molecular biology provides a new tool to explore taxonomic diversifica-
tion and the geographic distributions of lineages at the population level and among
closely-related species (Avise 2000). Given the unusually broad distribution of this
subtropical species of blenny, the high level of reef fish endemism at Rapa Nui, and
the taxonomic history of this species, phylogenetic analyses were conducted to evalu-
ate the taxonomy of *C. alboapicalis* and understand the processes that shaped its geo-
graphic distribution.
**Material and methods**

*Specimen collection.* Recent expeditions enabled collection of *Cirripectes* cf. *alboapicalis* specimens from Rangitāhua-Kermadec Islands (LL and TT in 2015), Gambier Islands (EDT, JTW, SP in 2010), Austral Islands (EDT, JTW, SP in 2013), and Rapa Nui (EDT, VN, ECG, CRE, PSA in 2016 and 2018), while additional expeditions to the Marquesas Islands (EDT, JTW, SP) and Manuae-Scilly (JTW, SP in 2014) allowed us to collect comparative tissue samples, resulting in a total of 43 specimens of *Cirripectes* spp. for this analysis (Table 1). A variety of collecting techniques were used (Hawai’ian slings, rotenone, clove oil and hand nets). Tissues were preserved in 96% EtOH at ambient temperature.

*Molecular analyses.* To conduct our genetic analysis, whole genomic DNA was extracted from fin clips preserved in 96% EtOH. DNA extraction was performed using GeneJet Genomic DNA purification kit (Thermo Fisher Scientific) or the DNeasy Blood & Tissue Kit (Qiagen), according to manufacturer's protocols. A fragment of the mitochondrial gene coding for cytochrome C oxidase subunit I (COI) was amplified with the primers designed by Ward et al. (2005). PCR amplifications and sequencing were performed following the protocol of Williams et al. (2012). A 650 base-pair fragment was sequenced from each of the 43 specimens of *Cirripectes* spp. and compared with COI sequences of congeners obtained from GenBank and BOLD, with a representative of the Labrisomidae used as the outgroup (Table 1). The closest relatives of *C. alboapicalis* based on morphology are two species with very restricted distributions: *Cirripectes obscurus* (Borodin 1927), a Hawai’ian endemic species; and *Cirripectes viriosus* (Williams 1988), endemic to the Batan Islands of Philippines (northern-most islands of the Philippines) (Figure 1). We included *C. obscurus* in our study, as we collected a single specimen that was morphologically consistent with this species in the Australs; unfortunately no tissues were available from *C. viriosus* for this study. All sequences are deposited in GenBank (Table 1) and metadata uploaded to the Genomics Observatory Metadatabase (GeOMe) (Deck et al. 2017).

Two tree-building methods were used to construct branching diagrams. First a Neighbor-joining (NJ) analysis based on the Kimura 2-parameter (K2P) model of sequence evolution (Kimura 1980) was conducted using the software package MEGA 6 (Tamura et al. 2013). Confidence in topology was evaluated by a bootstrap analysis with 1000 replicates (Felsenstein 1985). Second, a Maximum Likelihood (ML) analysis was performed using IQ-TREE (Minh et al. 2013, Nguyen et al. 2015) using the IQTREE Web Server (http://iqtree.cibiv.univie.ac.at). The best model of evolution for each partition was informed with ModelFinder (Kalyaanamoorthy et al. 2017) implemented in IQ-TREE prior to the construction of the ML tree. To assess branch support, the IQ-TREE analysis used the ultrafast bootstrap approximation (UFboot) with 1000 replicates (Minh et al. 2013) and the SH-like approximate likelihood ratio test (SH-aLRT) also with 1000 bootstrap replicates (Guindon et al. 2010). To visualize the relationships between haplotypes of *Cirripectes alboapicalis* and *C. obscurus* among the different sampling localities, a haplotype network was constructed using the haplonet
<table><caption>**Table 1.** Specimens collected for this study.</caption><thead><tr><th>Species</th><th>Geographic locality</th><th>Voucher number</th><th>GenBank number</th></tr></thead><tbody><tr><td rowspan="5">Cirripectes "patuki"</td><td>Rapa Nui</td><td>RN1</td><td>MH932003</td></tr><tr><td>Rapa Nui</td><td>RN2</td><td>MH932004</td></tr><tr><td>Rapa Nui</td><td>RN3</td><td>MH932005</td></tr><tr><td>Rapa Nui</td><td>RN4</td><td>MH932006</td></tr><tr><td>Rapa Nui</td><td>RN5</td><td>MH932007</td></tr><tr><td rowspan="6">Cirripectes sp. n.</td><td>Austral Islands</td><td>AUST-400</td><td>MH707846</td></tr><tr><td>Austral Islands</td><td>AUST-549</td><td>MH707848</td></tr><tr><td>Gambier Islands</td><td>GAM-511</td><td>MH707849</td></tr><tr><td>Gambier Islands</td><td>GAM-508</td><td>MH707847</td></tr><tr><td>Austral Islands</td><td>AUST-550</td><td>MH707850</td></tr><tr><td>Austral Islands</td><td>AUST-546</td><td>MH707855</td></tr><tr><td rowspan="2">Cirripectes "alboapicalis"</td><td>Kermadec Islands</td><td>Kermadec447</td><td>MH932008</td></tr><tr><td>Kermadec Islands</td><td>Kermadec448</td><td>MH932009</td></tr><tr><td rowspan="4">Cirripectes fuscoguttatus</td><td>Austral Islands</td><td>AUST-157</td><td>MH707851</td></tr><tr><td>Austral Islands</td><td>AUST-397</td><td>MH707852</td></tr><tr><td>Austral Islands</td><td>AUST-156</td><td>MH707853</td></tr><tr><td>Austral Islands</td><td>AUST-547</td><td>MH707854</td></tr><tr><td rowspan="15">Cirripectes jenningsi<br>Cirripectes quagga</td><td>Austral Islands</td><td>AUST-165</td><td>MH707856</td></tr><tr><td>Scilly Island</td><td>SCIL-193</td><td>MH707857</td></tr><tr><td>Austral Islands</td><td>AUST-403</td><td>MH707859</td></tr><tr><td>Austral Islands</td><td>AUST-536</td><td>MH707861</td></tr><tr><td>Gambier Islands</td><td>GAM-099</td><td>MH707863</td></tr><tr><td>Gambier Islands</td><td>GAM-110</td><td>MH707858</td></tr><tr><td>Gambier Islands</td><td>GAM-109</td><td>MH707864</td></tr><tr><td>Austral Islands</td><td>AUST-402</td><td>MH707865</td></tr><tr><td>Austral Islands</td><td>AUST-537</td><td>MH707860</td></tr><tr><td>Austral Islands</td><td>AUST-168</td><td>MH707862</td></tr><tr><td>Austral Islands</td><td>AUST-052</td><td>MH707867</td></tr><tr><td>Gambier Islands</td><td>GAM-144</td><td>MH707873</td></tr><tr><td>Austral Islands</td><td>AUST-164</td><td>MH707881</td></tr><tr><td>Gambier Islands</td><td>GAM-143</td><td>MH707869</td></tr><tr><td>Gambier Islands</td><td>GAM-145</td><td>MH707879</td></tr><tr><td>Gambier Islands</td><td>GAM-794</td><td>MH707876</td></tr><tr><td>Gambier Islands</td><td>GAM-737</td><td>MH707874</td></tr><tr><td>Gambier Islands</td><td>GAM-793</td><td>MH707877</td></tr><tr><td>Austral Islands</td><td>AUST-162</td><td>MH707870</td></tr><tr><td>Austral Islands</td><td>AUST-163</td><td>MH707880</td></tr><tr><td>Scilly Island</td><td>SCIL-194</td><td>MH707875</td></tr><tr><td>Scilly Island</td><td>SCIL-252</td><td>MH707866</td></tr><tr><td>Austral Islands</td><td>AUST-056</td><td>MH707868</td></tr><tr><td>Marquesas Islands</td><td>MARQ-071</td><td>MH707872</td></tr><tr><td>Marquesas Islands</td><td>MARQ-074</td><td>MH707871</td></tr><tr><td>Marquesas Islands</td><td>MARQ-073</td><td>MH707878</td></tr></tbody></table>

function of the package “pegas” (Paradis 2010) in the R statistical environment (R Core Team 2017). Finally, estimates of Net Evolutionary Divergence (NET) between the different groups of sequences observed were computed using the software package MEGA 6 (Tamura et al. 2013) and were conducted using the K2P model (Kimura 1980).
<figure><img src="image_3.png" /><figcaption>**Figure 1.** Geographic distribution of *Cirripectes alboapicalis*, *Cirripectes obscurus*, and *Cirripectes viriosus*</figcaption></figure>

**Results and discussion**

Molecular data were examined for 11 of the 23 valid species of the genus *Cirripectes* and included *C. obscurus*, one of the two hypothesized closest relatives of *C. alboapicalis* (based on color and morphological characters). Both the NJ and the ML analyses resulted in identical tree topologies and reveal three well-supported and highly divergent clades among the *C. alboapicalis* specimens. Clade 1 is composed of specimens from Rangitāhua-Kermadec Islands, Clade 2 of specimens from the Australs and Gambier Islands, while specimens from Rapa Nui form Clade 3 (Figure 2). The Clade 2 (Australs - Gambier) appears more closely related to the sister species *Cirripectes obscurus* than to the two other *C. alboapicalis* clades (Rangitāhua clade and Rapa Nui clade). The results from the haplotype network corroborate our phylogenetic results, as *C. alboapicalis* haplotypes form three highly divergent haplogroups. A single haplotype (from two specimens) is found in Rangitāhua and is separated by 23 mutations from a second haplogroup comprising sequences from Rapa Nui. A third haplogroup is found in the Gambier and Austral Islands and is separated by 86 mutations from the Rapa Nui haplogroup. Interestingly, the sister species, *C. obscurus*, is positioned between Clades 2 and 3 (Figure 3). Net divergence estimates ranged from 3.7 % (Clade 1–Clade 3) to 9.2 % (Clade 1–Clade 2) among the three *C. alboapicalis* clades. In contrast, net divergence between the three *C. alboapicalis* clades and *C. obscurus* ranged from 7.4 % to 7.9%. *C. alboapicalis* is thus composed of three lineages that are on different evolutionary trajectories.

Our molecular analysis reveals the existence of at least three cryptic species within the single species previously referred to as *Cirripectes alboapicalis*. In recent years, molecular studies have been combined with morphological methods and these integrated studies have led to the discovery of many new species (e.g., Baldwin et al. 2011; Delrieu-Trottin et al. 2014; and Williams and Viviani 2016). Our results provide strong justification for a detailed morphological analysis to identify diagnostic morphological
<figure><img src="image_4.png" /><figcaption>**Figure 2.** Maximum Likelihood tree for COI sequences with sequences representative of the maximum number of species retrieved from GenBank and BOLD. GenBank numbers are reported while BOLD numbers are denoted with an asterisk (*). Nodes show UFboot and SH-aLRT.</figcaption></figure>
<figure><img src="image_5.png" /></figure>

**Figure 3.** Haplotype network for the *Cirripectes alboapicalis* complex. COI sequences for *Cirripectes alboapicalis* from Austral Islands (Maria and Rurutu), Gambier Islands, Rangitāhua-Kermadec Islands (Raoul Island) and Rapa Nui. Sequence for *C. obscurus* from Austral Islands. Each circle corresponds to a unique sequence (i.e., haplotype); size of the circle indicates the frequency of the haplotype.

characters that may distinguish the genetically divergent species within *C. alboapicalis*. Williams (1998) did not have the advantage of being able to directly compare specimens of each lineage and might easily have overlooked subtle morphological characters that might now support a morphological diagnosis of each species in addition to the genetic differentiation. A thorough morphological analysis is needed to compare the voucher specimens from each genetic lineage and to examine fresh coloration to find distinguishing characters for the three species (Figure 4).

Given that the holotype of *C. alboapicalis* is from Lord Howe Island, the species name *alboapicalis* might be retained for Clade 1 as Rangitāhua is nearest to Lord Howe Island, unless further genetic investigation suggests that Rangitāhua also harbors a distinct lineage of *C. alboapicalis*. A new name will be needed for the specimens from the Australs and Gambier Islands (Clade 2) through a formal description, while the species name *patuki* should be elevated from synonymy and attributed to the Rapa Nui population (Clade 3) provided that morphological, coloration, or other diagnostic genetic characters are found. However, such a formal species description is beyond the scope of the current study.

Results of the present study have implications for the historical zoogeography of *Cirripectes* and the historical biogeography of the region. The discovery of a specimen morphologically consistent with *C. obscurus* in the Austral Islands suggests that this species is also present in the South Pacific, outside of the Hawai'i'ian Islands. Although there are no publicly available COI sequences for the Hawai'i'ian *C. obscurus* in Gen-Bank or BOLD, a search in the BOLD database using the identification tool (searching both public and private projects; Ratnasingham and Hebert 2007) estimated that our COI sequence for the *C. obscurus* from the Austral Islands was 99.84 % similar to sequences from three Hawai'i'ian *Cirripectes* larvae. Corroborating this notion that
<figure><img src="image_6.png" /><figcaption>(a)</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>(c)</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>(b)</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>(d)</figcaption></figure>

<figure><img src="image_10.png" /><figcaption>(e)</figcaption></figure>

**Figure 4.** Pictures of specimens from the three genetic clades of this study; a live colors (photograph by Richard Robinson (www.depth.co.nz)) and b freshly dead colors (photograph by Carl Struthers Museum of New Zealand Te Papa Tongarewa) of Clade 1 from Rangitāhua - Kermadec Islands c Clade 2, French Polynesia from Austral - Gambier Islands (photographs by Jeffrey T. Williams) d Clade 3 Rapa Nui (photograph by Erwan Delrieu-Trottin); and e *Cirripectes obscurus* (photograph by Jeffrey T. Williams).

*C. obscurus* may not be a Hawai’ian endemic, but has an antitropical distribution (as defined by Hubbs (1952) and Randall (1981)), Williams (1988) also identified a potential *C. obscurus* specimen in the Cook Islands. Nonetheless, the rarity of such *C. obscurus* specimens in our collections from the South Pacific raises questions about the size of this southern population.

The full extent of the geographic distribution of the three clades identified in the blenniid *Cirripectes alboapicalis* species complex is unclear, as genetic samples from several locations across the range of this species complex are presently not available (e.g., Rapa Iti, Pitcairn Islands, Norfolk Island), and more importantly none from the type locality, Lord Howe Island. Nonetheless, the geographic distribution of the clades may follow general biogeographic patterns observed in other South Pacific species possessing a Rapa Nui population. Randall and Cea (2011) describe 17 southern subtropical fish species present in Rapa Nui including *C. alboapicalis*. Of these species, the muraenid *Gymnothorax porphyreus* has the broadest distribution, from the southern Great Barrier Reef (GBR) to South of Chile, while an additional six species have continuous ranges between the southern GBR and Rapa Nui (Table 2). The remaining 10 species have either a very restricted distribution (e.g., *Itycirrhitus wilhelmi*,
<table><caption>**Table 2.** List of subtropical reef fish species that are present in Rapa Nui, and their geographic distribution (following Randall and Cea 2011). From east to west - NSW: New South Wales, S.GBR: Southern Great Barrier Reef, LH: Lord Howe Island, Nor: Norfolk Island, NC: New Caledonia, N.NZ: Northern New Zealand, R-K: Rangitāhua-Kermadec Islands, A: Austral Islands, G: Gambier Islands, Rapa: Rapa Iti, Pit.: Pitcairn, RN: Rapa Nui, JFer: Juan Fernandez, SanF: San Felix (Desventuradas Islands), Chile. Total: the total number of locations where the species is present. The three colors for *Cirripectes alboapicalis* denote the different genetic clades (see Figure 3), and grey in this row indicates the locations where the clade affinities are unknown.</caption><thead><tr><th>Species</th><th>NSW</th><th>S. GBR</th><th>LH</th><th>Nor</th><th>NC</th><th>N. NZ</th><th>R-K</th><th>A</th><th>G</th><th>RI</th><th>Pit</th><th>RN</th><th>JFer</th><th>SanF</th><th>Chile</th><th>Total</th></tr></thead><tbody><tr><td><i>Cirripectes alboapicalis</i></td><td>1</td><td>1</td><td>1</td><td>1</td><td></td><td></td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td></td><td></td><td></td><td></td><td>10</td></tr><tr><td><i>Gymnothorax porphyreus</i></td><td></td><td></td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td></td><td></td><td>1</td><td></td><td>1</td><td>1</td><td>1</td><td>1</td><td>10</td></tr><tr><td><i>Anampses femininus</i></td><td>1</td><td>1</td><td>1</td><td></td><td></td><td></td><td></td><td>1</td><td>1</td><td>1</td><td>1</td><td>1</td><td></td><td></td><td></td><td>9</td></tr><tr><td><i>Bodianus unimaculatus</i></td><td>1</td><td>1</td><td>1</td><td>1</td><td></td><td>1</td><td>1</td><td></td><td></td><td>1</td><td></td><td>1</td><td></td><td></td><td></td><td>8</td></tr><tr><td><i>Enchelycore ramosa</i></td><td>1</td><td></td><td>1</td><td>1</td><td></td><td>1</td><td>1</td><td></td><td></td><td>1</td><td></td><td>1</td><td></td><td></td><td></td><td>7</td></tr><tr><td><i>Trachypoma macracanthus</i></td><td>1</td><td></td><td>1</td><td>1</td><td></td><td>1</td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>5</td></tr><tr><td><i>Centropyge hotumatua</i></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td>1</td><td>1</td><td>1</td><td></td><td></td><td></td><td></td><td>4</td></tr><tr><td><i>Aseraggodes bahamondei</i></td><td></td><td></td><td></td><td>1</td><td>1</td><td></td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td><td></td><td>4</td></tr><tr><td><i>Priolepis psygmophilia</i></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td></td><td>1</td><td>1</td><td></td><td></td><td></td><td></td><td></td><td>3</td></tr><tr><td><i>Gymnothorax nasuta</i></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td>1</td><td>1</td><td></td><td></td><td></td><td></td><td>3</td></tr><tr><td><i>Itycirrhitus wilhelmi</i></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td>1</td><td></td><td></td><td></td><td>2</td></tr><tr><td><i>Goniistius plessisi</i></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td>1</td><td></td><td></td><td></td><td>2</td></tr><tr><td><i>Chrysiptera rapanui</i></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td><td>2</td></tr><tr><td><i>Bathystethus orientale</i></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td></td><td>1</td><td></td><td></td><td></td><td>2</td></tr></tbody></table>

*Goniistius plessisi*, *Centropyge hotumatua*) or disjunct distributions with populations in both Rangitāhua-Kermadec and Rapa Nui regions (e.g., *Aseraggodes bahamondei*, *Priolepis psygmophilia*, *Chrysiptera rapanui*, see Table 2). This distribution pattern is identified as the Pitcairn-Kermadec “Province” by Rehder (1980) and includes Rapa Nui, Pitcairn, Rapa Iti, and the Rangitāhua-Kermadec Islands. Interestingly, our results suggest that the Rangitāhua-Kermadec and the Rapa Nui clades are closely related. The closest relatives of several Rapa Nui endemic species are endemic species of Rangitāhua (e.g., *Acanthistius fuscus* and *A. cinctus*, *Girella nebulosa* and *G. fimbriata*). It is thus highly likely that both the Kermadec and the Rapa Nui clades have very restricted distributions and emerged via an allopatric process following a chance colonization.

## Acknowledgements

We thank Rebeca Tepano, Nina, Taveke Olivares Rapu, Liza Garrido Toleado (SER-NAPESCA), Ludovic Tuki (Mesa del Mar), and the people of the Rapa Nui Island for their kind and generous support. Collections from Rangitāhua-Kermadec Islands were made possible by the *RV Braveheart* crew (Stoney Creek Shipping Company Ltd.), with support from the Auckland Museum Institute, Massey University, the Pew Charitable Trusts, and in collaboration with Natural History New Zealand. We are grateful for the support of Rangitāhua mana moana, the Māori iwi Ngāti Kuri and Te
Aupōuri and fieldwork help from J. David Aguirre, Phil Ross, and Sam McCormack. We thank Tea Frogier and Pierre Mery for their support of the Coralspot project at the Gambier Archipelago. The Coralspot expedition was funded by the “Contrat de projet Etat-Polynésie”, by the ANR “IMODEL” and the French Ministry for Environment, Sustainable Development and Transport (MEDDTL). The Austral Islands expedition was part of the Global Reef Expedition and the work presented here is based in part on specimens collected in the Austral Islands made possible due to the support of the Khaled bin Sultan Living Oceans Foundation. We are grateful to Pierre Sasal, Tom Cribb, René Galzin and Michel Kulbicki, for their field assistance in the Gambier and the Austral Islands, along with the crew of the *Claymore II* and of the *Golden Shadow*. E. Delrieu-Trottin was supported by FONDECYT Postdoctorado fellowship N°3160692 and P. Saenz-Agudelo by the FONDECYT Iniciación fellowship N°11140121. L. Liggins was supported by a Rutherford Foundation Postdoctoral Fellowship. The authors declare no conflict of interest. All applicable institutional guidelines for the care and use of animals were followed. Specimens were collected in Rapa Nui under permit No. 1042, March, 21<sup>th</sup> 2018 obtained from the Chilean Subsecretary of Fishing, and No. 13270/24/162/Vrs., March, 29<sup>th</sup> 2018 obtained from Armada de Chile; Servicio Hidrografico y Oceanografico. Specimens were collected in Kermadec Islands under Authorization number: 47976-MAR from the New Zealand Department of Conservation. The Universidad Austral de Chile Ethical Care Committee and Biosecurity Protocol approved our use and handling of animals. Finally, we thank M. Erdmann for constructive comments on an earlier version of the manuscript.

## References

Allen GR (2008) Conservation hotspots of biodiversity and endemism for Indo-Pacific coral reef fishes. Aquatic Conservation: Marine and Freshwater Ecosystems 18: 541–556. https://doi.org/10.1002/aqc.880

Avise JC (2000) Phylogeography: The History and Formation of Species. Harvard University Press.

Baldwin CC, Castillo CI, Weigt LA, Victor BC (2011) Seven new species within western Atlantic *Starksia atlantica*, *S. lepicoelia*, and *S. sluiteri* (Teleostei, Labrisomidae), with comments on congruence of DNA barcodes and species. ZooKeys: 79: 21–72. https://doi.org/10.3897/zookeys.79.1045

Bellwood DR, Wainwright PC (2002) The History and Biogeography of Fishes on Coral Reefs. In: Sale PS (Ed.) Coral Reef Fishes: dynamic and diversity in a complex ecosystem. Elsevier, San Diego, 5–32. https://doi.org/10.1016/B978-012615185-5/50003-7

Borodin NA (1927) A new blenny from the Hawaiian Islands. American Museum Novitates 281: 1–2.

Briggs JC (2009) Diversity, endemism and evolution in the Coral Triangle. Journal of Biogeography 36: 2008–2010. https://doi.org/10.1111/j.1365-2699.2009.02146.x

De Buen F (1963) Los peces de la Isla de Pascua. Bol de la Soc de Biol de Concepcion 35: 3–80.
Carpenter KE, Springer VG (2005) The center of the center of marine shore fish biodiversity: The Philippine Islands. Environmental Biology of Fishes 72: 467–480. https://doi.org/10.1007/s10641-004-3154-4

Connolly SR, Bellwood DR, Hughes TP (2003) Indo-pacific biodiversity of coral reefs: Deviations from a mid-domain model. Ecology 84: 2178–2190. https://doi.org/10.1890/02-0254

Deck J, Gaither MR, Ewing R, Bird CE, Davies N, Meyer C, Riginos C, Toonen RJ, Crandall ED (2017) The Genomic Observatories Metadatabase (GeOMe): A new repository for field and sampling event metadata associated with genetic samples. PLoS Biology. https://doi.org/10.1371/journal.pbio.2002925

Delrieu-Trottin E, Williams JT, Planes S (2014) *Macropharyngodon pakoko*, a new species of wrasse (Teleostei: Labridae) endemic to the Marquesas Islands, French polynesia. Zootaxa 3857: 433–443. https://doi.org/10.11646/zootaxa.3857.3.6

Felsenstein J (1985) Phylogenies and the Comparative Method. The American Naturalist 125: 1–15. https://doi.org/10.1086/284325

Friedlander AM, Ballesteros E, Beets J, Berkenpas E, Gaymer CF, Gorny M, Sala E (2013) Effects of isolation and fishing on the marine ecosystems of Easter Island and Salas y Gómez, Chile. Aquatic Conservation: Marine and Freshwater Ecosystems 23: 515–531. https://doi.org/10.1002/aqc.2333

Guindon S, Dufayard J-F, Lefort V, Anisimova M, Hordijk W, Gascuel O (2010) New algorithms and methods to estimate maximum-likelihood phylogenies: assessing the performance of PhyML 3.0. Systematic biology 59: 307–321. https://doi.org/10.1093/sysbio/syq010

Hubbs CL (1952) Antitropical distribution of fishes and other organisms. Symposium on problems of bipolarity and of pantemperate faunas. Proceedings of the Seventh Pacific Science Congress (Pacific Science Association) 3: 324–329.

Kalyaanamoorthy S, Minh BQ, Wong TKF, von Haeseler A, Jermiin LS (2017) ModelFinder: fast model selection for accurate phylogenetic estimates. Nature Methods 14: 587–589. https://doi.org/10.1038/nmeth.4285

Kimura M (1980) A simple method for estimating evolutionary rates of base substitutions through comparative studies of nucleotide sequences. Journal of Molecular Evolution 16: 111–120. https://doi.org/10.1007/BF01731581

Minh BQ, Nguyen MAT, von Haeseler A (2013) Ultrafast approximation for phylogenetic bootstrap. Molecular Biology and Evolution 30: 1188–1195. https://doi.org/10.1093/mol-bev/mst024

Nguyen LT, Schmidt HA, von Haeseler A, Minh BQ (2015) IQ-TREE: A fast and effective stochastic algorithm for estimating maximum-likelihood phylogenies. Molecular Biology and Evolution 32: 268–274. https://doi.org/10.1093/molbev/msu300

Ogilby JD (1899) Additions to the fauna of Lord Howe Island. Proceedings of the Linnean Society of New South Wales 23: 730–745.

Paradis E (2010) pegas: an R package for population genetics with an integrated-modular approach. Bioinformatics 26: 419–420. https://doi.org/10.1093/bioinformatics/btp696

R Core Team (2017) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org/
Randall JE (1976) The endemic shore fishes of the Hawaiian Islands, Lord Howe Island and Easter Island. Colloque Commerson, 1973. ORSTOM Travaux et Documents 47: 49–73. http://hohorizon/documentation.ird.fr/exl-doc/pleins_textes/pleins_textes_5/pt5/travaux_d/29300.pdf

Randall JE (1981) Examples of antitropical and antiequatorial distribution of Indo-West-Pacific fishes. Pacific Science 35: 197–209.

Randall JE, Cea A (2011) Shore Fishes of Easter Island. University of Hawai'i Press, 164 pp. http://books.google.com/books?hl=en&lr=&id=iXtCTSRTcb8C&pgis=1

Ratnasingham S, Hebert PDN (2007) BOLD: The Barcode of Life Data System (www.barcodinglife.org). Molecular Ecology Notes 7: 355–364. https://doi.org/10.1111/j.1471-8286.2007.01678.x

Rehder HA (1980) The marine mollusks of Easter Island (Isla de Pascua) and Sala y Gómez. Smithsonian Contributions to Zoology 289: 1–176. https://doi.org/10.5479/si.00810282.289

Tamura K, Stecher G, Peterson D, Filipski A, Kumar S (2013) MEGA6: molecular evolutionary genetics analysis version 6.0. Molecular Biology and Evolution 30: 2725–2729. https://doi.org/10.1093/molbev/mst197

Ward RD, Zemlak TS, Innes BH, Last PR, Hebert PDN (2005) DNA barcoding Australia's fish species. Philosophical Transactions of the Royal Society B: Biological Sciences 360: 1847–1857. https://doi.org/10.1098/rstb.2005.1716

Williams JT (1988) Revision and phylogenetic relationships of the blenniid fish genus *Cirripedes*. Bernice Pauahi Bishop Museum, 78 pp.

Williams JT, Delrieu-Trottin E, Planes S (2012) A new species of Indo-Pacific fish, *Canthigaster criobe*, with comments on other *Canthigaster* (Tetraodontiformes: Tetraodontidae) at the Gambier Archipelago. Zootaxa 3523: 80–88.

Williams JT, Viviani J (2016) *Pseudogramma polyacantha* complex (Serranidae, tribe Grammistini): DNA barcoding results lead to the discovery of three cryptic species, including two new species from French Polynesia. Zootaxa 4111: 246–260. https://doi.org/10.11646/zootaxa.4111.3.3