A New Genus and Species of Pygmy Pipehorse from Taitokerau Northland, Aotearoa New Zealand, with a Redescription of Acentronura Kaup, 1853 and Idiotropiscis Whitley, 1947 (Teleostei, Syngnathidae)

Cylix tupareomanaia, new genus and species, is described from three specimens (35.5–55.5 mm SL), collected from rocky reefs at 12–17 m depth from Taitokerau Northland, New Zealand. The new taxon shares morphological synapomorphies with the superficially similar Australian endemic Idiotropiscis and Indo-Pacific Acentronura, including head angled ventrally approximately 25° from the principal body axis, enclosed brood pouch, brood pouch plates, prehensile tail, and absence of caudal fin. Cylix tupareomanaia, new genus and species, however, is distinguishable from all other members of the Syngnathidae by the following combination of bony autapomorphic characters: a cup-like crest present anterodorsally on the supraoccipital; and large conspicuous midventral conical spines on the cleithral symphysis and first trunk ring between the pectoral-fin bases. The new species can be further differentiated by genetic divergence in the mitochondrial COX1 gene from Acentronura breviperula, A. tentaculata, Idiotropiscis australe, and I. lumnitzeri (estimated uncorrected p-distances of 19.5%, 20.4%, 17.9%, and 18.4%, respectively). A phylogenetic hypothesis from the analysis of two nuclear loci, 18S and TMO-4C4, supports the placement of C. tupareomanaia, new genus and species, as the sister taxon to a clade comprising the genera Acentronura and Idiotropiscis. Cylix tupareomanaia, new genus and species, represents the eighth member within the pygmy pipehorse clade to be described from the Indo-Pacific and the first new genus and species of syngnathid to be reported from New Zealand since 1921.

S YNGNATHIDAE is a large and morphologically distinctive group of predominantly marine fishes, with 57 genera and 300 described species that include the seahorses, pipefishes, pygmy pipehorses, and seadragons (Dawson, 1985;Hamilton et al., 2017;WoRMS Editorial Board, 2021). Syngnathids primarily inhabit shallow coastal waters in temperate and tropical oceans, and are characterized by male brooding, a unique overall body plan, including an elongated snout, fused jaw, the absence of pelvic fins, thick plates of bony armor, and behavioral and morphological adaptations for crypsis.
The inshore marine ichthyofauna of New Zealand includes a small but diverse group of syngnathids represented by ten species in five genera: Hippocampus, Leptonotus, Lissocampus, Solegnathus, and Stigmatopora (Dawson, 1980(Dawson, , 1985Roberts et al., 2015;Clark et al., 2017). Four species of syngnathids are endemic to New Zealand, including Lissocampus filum, a kelp-associated species, Stigmatopora macropterygia, the largest member of its genus, and two uncommon sand and rubble-associated species, Leptonotus elevatus and L. norae, that belong to a Pacific genus with a disjunct distribution with the only other species, L. blainvilleanus, occurring in South America. In contrast, syngnathid diversity in nearby Australia is exceptionally high with 129 species represented in 47 genera, 11 of which are monotypic (Dawson, 1985;Browne et al., 2008;Baker et al., 2009;Hamilton et al., 2017). All genera of syngnathids that occur in temperate mainland New Zealand, with the exception of Leptonotus, occur in southern Australia (Dawson, 1985). Similarly, New Caledonia, which is linked to New Zealand by the almost entirely submerged continental landmass Te Riu-a-Māui Zealandia (Mortimer et al., 2017), exhibits high syngnathid diversity and endemism with 41 species in 14 genera (Fricke et al., 2011).
Recent surveys of inshore marine biodiversity at the offshore subtropical Rangitāhua Kermadec Islands in the northernmost region of New Zealand produced new records of Indo-Pacific syngnathids Trnski et al., 2015;Clark et al., 2017). These surveys yielded the pipefish species Cosmocampus howensis, Halicampus boothae, and the rare southwest Pacific seahorse Hippocampus jugumus, all of which were originally described based on specimens collected from Lord Howe Island, Australia (Whitley, 1948;Allen et al., 1976;Smith et al., 2010). In 2009 and 2014, the Bay of Islands Coastal Survey Project, coordinated by the National Institute of Water and Atmospheric Research (NIWA), conducted extensive marine biodiversity surveys of shallow water coastal habitats in the Northland region of New Zealand, including the Bay of Islands and the Cavalli Islands. These surveys each yielded two individuals of a diminutive syngnathid (Jones et al., 2009;NIWA, 2014: https://niwa.co.nz/news/rare-fish-and-new-seafloor-habitatsfound-during-niwa-survey-of-coastal-east-northland) that were provisionally identified as the Australian pygmy pipehorse Idiotropiscis australe based on a superficial similarity to this species (Stewart, 2015).
Members of the genus Idiotropiscis belong to a grouping of Indo-Pacific species of pygmy pipehorses comprising the genera Acentronura and Kyonemichthys, all of which have the head angled slightly ventrally from the abdominal axis, a fully enclosed male brood pouch, prehensile tail, and no caudal fin. The Western Atlantic pygmy pipehorse genus Amphelikturus appears to have evolved independently in the Atlantic to the extent that Dawson (1984) suggested all pygmy pipehorses shared a common ancestor; however, molecular and morphological differences support the findings of independent evolution of Atlantic and Pacific pygmy pipehorses (Hamilton et al., 2017). A multi-gene phylogenetic hypothesis of relationships of the family Syngnathidae recovered Acentronura and Idiotropiscis as sister taxa within a clade of highly morphologically distinct Indo-Pacific pipefish genera Filicampus, Trachyrhamphus, Haliichthys, and Lissocampus (Hamilton et al., 2017). Even though Acentronura and Idiotropiscis share the synapomorphy of fully enclosed brood pouch, prehensile tail, and absence of caudal fin with the seahorse genus Hippocampus, no immediate sister taxon relationship was supported among these genera (Hamilton et al., 2017). Instead, a sister-group relationship was recovered between the Indo-Pacific clade containing Acentronura and Idiotropiscis and a globally distributed and welldefined clade of seahorses (Hamilton et al., 2017). The three previously described species of the genus Idiotropiscis, I. australe (type species of the genus), I. larsonae, and I. lumnitzeri, are endemic to the shallow coastal waters of Australia (Waite and Hale, 1921;Dawson, 1984;Kuiter, 2004). Idiotropiscis australe occurs in South Australia and southern Western Australia, I. larsonae in northern Western Australia, and I. lumnitzeri in southern New South Wales.
Although the collected specimens from northern New Zealand appeared superficially similar in appearance to I. australe based on shared synapomorphies, such as the head angled ventrally approximately 258 from the principal body axis, a fully enclosed brood pouch, brood pouch plates, prehensile tail, and absence of caudal fin (Stewart, 2015), closer investigation revealed a number of unique morphological characters present on the head that differed markedly from I. australe, and with features unknown from any other species of pygmy pipehorse described previously. On the basis of these morphological features, molecular sequence data, and phylogenetic analysis, we consider the species from Taitokerau, Northland, New Zealand as a new genus and species of pygmy pipehorse in the family Syngnathidae, and we describe it herein. Non-type representatives of the superficially similar Acentronura and Idiotropiscis are redescribed based on a substantially expanded dataset of morphological characters (compared to the original descriptions), as revealed by micro-computed tomography. Comparisons of these morphological characters revealed novel species-specific neurocranial characters that assisted in the identification of the generic limits of Acentronura, Idiotropiscis, and Cylix, new genus.

MATERIALS AND METHODS
Morphological analyses.-Head and body measurements reported follow Short et al. (2018) and are expressed as percent of standard length (SL) or head length (HL). Osteocranial and postcranial skeletal terminology follows Leysen (2011). External morphological characters were documented using a dissecting microscope and analyses of high-resolution digital images. Morphological characters of the axial skeleton of type specimens and comparative material were examined via non-destructive x-ray microcomputed tomography (lCT) at the Karel F. Liem Bioimaging Facility (Friday Harbor Laboratories, University of Washington). Micro-computed tomography (lCT) was performed using a Bruker Skyscan 1173 scanner (Billerica, MA) with a 1 mm aluminum filter at 60 kV and 110 lA on a 2048 3 2048 pixel CCD at a resolution of 8.8 lm. The specimens were placed inside a 50 ml plastic Falcon tube (Corning, NY), supported by two thin foam pads to prevent movement during scanning and wrapped in 70% ethanol-infused cheesecloth to maintain moist conditions and prevent desiccation. The resulting lCT data were visualized, segmented, and rendered in Horos software (https://horosproject. org).
Specimens examined are housed in the following museum collections: Auckland War Memorial Museum (AIM); Australian Museum, Sydney (AMS); Museum of New Zealand Te Papa Tongarewa (NMNZ); South Australian Museum, Adelaide (SAMA); Western Australian Museum, Perth (WAM); Museum and Art Gallery of the Northern Territory, Darwin (NTM). Institutional abbreviations follow Sabaj (2020). Georeferenced locations for the type specimens of C. tupareomanaia, new genus and species, were captured on GPS units and use WGS84 datum.
Molecular analyses.-DNA extraction, primers, PCR conditions, sequence alignment, and analysis of COX1 and nuclear sequence data generated for this study, as well as previously published mitochondrial and nuclear sequence data, were performed following protocols described in Hamilton et al. (2017). COX1 sequence data for C. tupareomanaia, new genus and species, in this study followed protocols described in Eme et al. (2020). A partial segment of mitochondrial cytochrome c oxidase subunit I (COX1) DNA was sequenced from a tail clipping of a specimen from the type locality of C. tupareomanaia, new genus and species, (AIM MA122275) and a specimen of I. australe (SAMA F2657). COX1 sequence data was compared to the previously sequenced pygmy pipehorse species A. breviperula, A. tentaculata, and I. lumnitzeri (available from Hamilton et al., 2017) in order to calculate genetic distances (uncorrected pdistances) in MEGA v. 7.0.26 (Kumar et al., 2018). The phylogenetic position of the new species was investigated among the morphologically similar pygmy pipehorse species A. breviperula, A. tentaculata, and I. lumnitzeri, and sampled members of Hippocampus based on the nuclear markers 18s ribosomal (18S) and anonymous putative titin-like protein (TMO-4C4), which were derived in this study and from Hamilton et al. (2017) employing Maximum Likelihood (ML), Maximum Parsimony (MP), and MrBayes analyses (Appendix 1). DNA sequences for the two gene markers were assembled, aligned, and concatenated using Geneious v. 11.1.4 (Biomatters, Ltd., Auckland). The aligned dataset was imported into MEGA v.7.0.26 (Kumar et al., 2018) for ML and MP analyses. ML analyses were evaluated using bootstrapping with 1,000 replicates for topological support. The resulting best scoring ML phylogram was rooted with the southern Australian trunk-brooder pipefish Heraldia nocturna and viewed using FIGTREE v.1.3.1 (http://tree.bio.ed.ac.uk/ software/figtree/). MP analyses were conducted with 1,000 bootstrap replicates using a full heuristic search utilizing treebisection and reconnection (TBR) branch swapping. All characters were weighted equally and unordered. Resulting equally parsimonious cladograms were rooted with H. nocturna, summarized using a strict consensus method, and viewed using FIGTREE v1.3.1. The Bayesian analyses were performed following protocols described in Hamilton et al. (2017) using MrBayes v.3.2 (Ronquist et al., 2012 with settings as follows: GTR substitution model for 18S and TMO-4C4 with a gamma-distributed rate parameter applied, two Metropolis-coupled Markov Chain Monte Carlo (MCMC) runs, and each with four chains. The analyses ran for 10 million generations sampling trees and parameters every 1,000 generations.
Diagnosis.-A genus of the Syngnathidae that shares numerous morphological synapomorphies with Acentronura and Idiotropiscis, including head angled ventrally approximately 258 from the principal body axis, enclosed brood pouch, brood pouch plates, prehensile tail, and absence of caudal fin. However, Cylix tupareomanaia, new species, differs from all other genera by unique anatomical features of the head, including: a distinct, cup-like crest present anterodorsally on the supraoccipital; and large and conspicuous medioventral conical spines on the cleithral symphysis and the first trunk ring between the pectoral-fin bases. It differs further in having the following combination of morphological characters: prominent supraoccipital; continuous cleithrum; prominent supracleithrum; anterior nuchal plate absent; posterior nuchal plate present with bony dorsomedial crest; large gap present between the supraoccipital and posterior nuchal plate; one to three dorsal spines at midline of snout, posteriormost of these spines large; one large double and rugose lateral head spine present below the cup-like supraoccipital crest; three small blunt lateral head spines on operculum; rim of orbit elevated dorsolaterally and strongly ventrally; two spines on cleithral ring; large rugose spine anterior to ventral third of pectoral-fin base; moderate-sized spine at ventral extent of head; small spine present posterolateral to the pelvic-fin base; four subdorsal spines, forming a square, the dorsal two enlarged.
Etymology.-The generic name Cylix is derived from the Greek kylix, meaning cup or chalice, in reference to the cuplike crest present on the head. Gender masculine. Description.-Morphometric and meristic characters of the three type specimens listed in Table 1. Trunk rings 13-14; tail rings 35-36; anal-fin rays 4; subdorsal rings 3 (spans one trunk ring and two tail rings); dorsal-fin rays 14; anal-fin rays 4; pectoral-fin rays 14. Body slender; head large relative to body, angled ventrally approximately 258 from the principal body axis, the dorsal profile pyramidal in lateral aspect, rising steeply from snout to elevated and prominent supraoccipital; distinct cup-like crest (SC) present anterodorsally on the supraoccipital well behind the eye, height moderate, pentamerous in dorsal view, divided transversally into two concave sections (Figs. 3,4); cleithral and supracleithral ridge prominent (Fig. 4); posterior margins of pentamerous crest on supraoccipital fused and equal in height to cleithrum; anterior nuchal plate absent; posterior nuchal plate present with bony dorsomedial crest; large gap between the supraoccipital and posterior nuchal plate; gill openings small, bilateral; rim of orbit with prominent dorsolateral and ventral ridges, fluted with rugose sculpturing; opercular ridge low, entire, angled dorsally toward gill opening; swelling of gular region posteroventrally of eye, forming a transverse pair of blunt protuberances; pectoral-fin base without distinct ridges, one strongly elevated ventrolateral bulge (Fig. 4); dorsal-fin origin on 12 th trunk ring, fin base elevated; superior trunk ridge discontinuous with superior tail ridge below dorsal-fin base; lateral trunk ridge continuous with inferior tail ridge; inferior tail ridge ends on anal trunk ring; dorsum of anteriormost two trunk rings distinctly broader than posterior trunk rings; trunk in lateral view narrowest at 1 st and 2 nd trunk rings where angle of head forms from body axis, broadest at 5 th trunk ring; principal body ridges distinct and moderately elevated; tail rings of uniform depth over most of length, becoming progressively shorter and smaller near posterior tip; tail prehensile; scutella not evident. Large spine present on dorsal midline of snout on the ethmoid area, at confluence with the anterior ends of supraorbital ridges, its height extended well above level of nares; none to two smaller medial spines anterior to the large spine on the snout, on the mesethmoid bone (principal dorsal spine and one anterior spine in paratype NMNZ P.056154, principal spine with anterior dorsal spines or elevations absent in paratype NMNZ P.046322); distinct median frontal spine at convergence of anterior edges of the cup-like supraoccipital crest, protruding anteriorly; four lateral head spines, one large double and rugose lateral head spine directly below the cup-like supraoccipital crest, three small blunt spines on operculum aligned 55-588 relative to the ventral axis of the head, the dorsal and ventral blunt spines connecting to terminal elements of the opercular ridge; large, conspicuous midventral conical spines on the cleithral symphysis and the first trunk ring between the pectoral-fin bases (Figs. 3, 5); two spines on cleithral ring, large rugose spine anterior to ventral third of pectoral-fin base, moderate-sized spine at ventral extent of head; small spine present posterolaterally of the pectoral-fin base (Figs. 3,5); superior trunk ridges with spines of small to moderate size, enlarged blunt spines dorsally on 3 rd , 6 th , 10 th , 11 th , and 12 th rings, all bearing dermal flaps; lateral trunk ridges with moderate-sized spines on each trunk ring starting at 2 nd ring with enlarged spines on 3 rd , 6 th , and 10 th rings; inferior trunk ridges with moderate-sized spines starting at 3 rd ring with enlarged spines on 3 rd , 6 th , and 10 th rings; subdorsal spines four, superior trunk ridge ending with two subdorsal spines, the anteriormost spine large and conspicuous, superior tail ridge commencing with two subdorsal spines, posteriormost spine reduced, in alignment with larger subdorsal spines above; superior tail ridge spines well developed anteriorly, except on first and second ring, with enlarged spines on 3 rd , 4 th , 7 th , and 11 th tail ridges, gradually reducing in size to 22 nd trunk ring; lateral tail ridge spines absent; inferior tail ridge spines well developed to 8 th tail ring. Simple and branched dermal appendages present on head: long simple appendages extending anteriorly from dorsal rim of orbit, long and branched appendages ventrodorsally of each eye.
Cylix tupareomanaia exhibits strong sexual dimorphism with an enclosed brood pouch in male paratype NMNZ P.046322 (Fig. 2). The brood pouch is located along the ventral midline of the tail below the anteriormost ten tail rings. It is enclosed by ten arcuate bony extensions (Fig. 4) that extend ventrolaterally from the anterior ventral plate ridges of the tail, and progressively reduce in size posteriorly. The ten brood pouch plates are similar in appearance, whereas the posteriormost pouch plate is diminutive in size.
Coloration.-Holotype in life (Fig. 6A), head, trunk, and tail red; ventrolateral margin of trunk pale red to white; dorsum of head and snout speckled with fine white dots; pentamerous crest on supraoccipital red; snout spines, supraoccipital spine, anterior continuations of supraorbital ridges, and dorsal rim of orbit pale brown to white; white band extending from just behind the eye, grading posteriorly into a reticulated pattern of irregular, roundish quadrilaterals delineated by white coloration, concentrated on operculum and pectoral-fin base; reticulated pattern diffused laterally on head, pale brown to white; dorsal-fin base white with reticulated pattern, proximal third of dorsal-fin red; two parallel rows of rounded quadrilaterals present on trunk and tail rings, four quadrilaterals per ring; medioventral conical spines on the cleithral symphysis and the first trunk ring between the pectoral-fin bases pale brown to white. Fleshy appendages, pale brown to white, present on the frontal spine, principal snout spine, dorsum of rim of orbit, ventrolateral of snout, 3 rd and 6 th superior trunk ridge spines, and 3 rd and 7 th superior tail ridge spines. Other individuals of C. tupareomanaia observed at the type location and the Poor Knights Islands exhibited red and white countershading coloration or background color typically uniformly pale orange to dark red, respectively ( Fig. 6B-F). In alcohol, head and body color pale cream to light brown. Fins hyaline.
Distribution and habitat.-Cylix tupareomanaia is thus far known only from Taitokerau Northland, New Zealand, including Pēwhairangi (Bay of Islands), Nukutaunga (Cavalli Islands), Tawhiti Rahi and Aorangi (Poor Knights Islands), and the coastal headlands off Whangaruru (Fig. 7). At the type locality, C. tupareomanaia was observed in mixed habitat on a vertical rock wall that was covered in encrusting coralline algae, bryozoans, sponges, solitary corals, and turf algae, and which faced a rocky outcrop exposed to the open ocean. The rock wall was subject to moderate ocean swell as was evident from the accumulated debris of detached and decomposed algae on the sandy to rubble bottom of the channel at a depth of 17-18 m. The holotype was collected below the Ecklonia radiata kelp line; it was observed moving about in close proximity to another individual of the same species, which appeared to represent a male-female pair. Additional reef fishes observed on and at the base of the rock wall included: Gobiopsis atrata (Gobiidae); Forsterygion flavonigrum, F. maryannae, and Notoclinops segmentatus (Tripterygiidae); Aplodactylus arctidens (Aplodactylidae); Coris sandeyeri and Notolabrus tetricus (Labridae); Chromis dispilus (Pomacentridae); and Chrysophrys auratus (Sparidae).
Species composition and biodiversity around the North Island of New Zealand indicate subdivision of inshore marine reef ichthyofauna into three regional biogeographic groups or eco-regions, including: western North Island coast; northeastern North Island coast and offshore islands; and Manawatāwhi Three Kings Islands (Brook, 2002). Cylix tupareomanaia may be restricted to the warm temperate waters off the north-eastern coast of the North Island and its offshore islands where it has been collected and observed. The coastal headlands and offshore islands are strongly influenced by oceanic water masses and reflect higher overall species diversity (Brook, 2002); therefore, the new taxon may not occur in the other cooler regional biogeographic areas. Its occurrence further north and south, however, may be confirmed by comprehensive sampling for this cryptic species. The new species is likely endemic to temperate New Zealand; no observations as of yet have been recorded at Rangitāhua the Kermadec Islands, where more than 90% of the coastal ichthyofauna are of subtropical and tropical Indo-Pacific origin, in temperate or tropical Australia, including its offshore subtropical territories of Lord Howe and Norfolk Islands, nor in New Caledonia (Allen et al., 1976;Francis, 1993;Francis and Randall, 1993;Johnson, 1999;Hutchins, 2001  Cryptic fish assemblages on temperate rocky reefs in New Zealand are dominated by the highly diverse triplefins (Tripterygiidae) and clingfishes (Gobiesocidae) and exhibit a high degree of endemism (Paulin and Roberts, 1993;Hickey et al., 2009;Roberts et al., 2015;Conway et al., 2017Conway et al., , 2018. Other diminutive cryptic reef species recorded include the blennies (Blenniidae), kelpfishes (Clinidae), gobies (Gobiidae), and pipefishes and seahorses (Syngnathidae). The recent discovery of the highly cryptic C. tupareomanaia is therefore a noteworthy addition to reef fish diversity in New Zealand based on the fact it hadn't been collected or observed in numerous biodiversity surveys of temperate marine ichthyofauna previously conducted in a wide range of habitats. These surveys were carried out in estuaries, shallow coastal bays, seagrass meadows, mangrove forests, open mainland coasts, peninsulas, nearshore islands, and passages within the Bay of Islands (Nicholson, 1979;Nicholson and Roberts, 1980;Francis et al., 2005Francis et al., , 2011Kelly, 2007;Jones et al., 2009;Gordon et al., 2010), throughout northern New Zealand (Willan et al., 1979;Brook, 2002;Morrison et al., 2002Morrison et al., , 2014Francis et al., 2005;Leathwick et al., 2006;Edgar et al., 2013), along the coast of the East Cape Region (Roberts and Stewart, 2006), at various inshore and offshore islands, including Manawatāwhi Three Kings Islands (Hardy et al., 1987), Cavalli Islands (Nicholson, 1979), the Poor Knights Islands (Russell, 1970;Kelly, 2007), Aotea Great Barrier Island (Roberts et al., 1986;Sivaguru and Grace, 2004), the Mokohinau Islands (Housley, 1980), Hen Island (Willis, 1995), Cuvier Islands (Housley et al., 1981), Ahuahu Grea Mercury Island (Grace, 1976), Aldermen Islands (Grace, 1973), the Chatham Islands (Roberts, 1991), in the South Island (Francis, 1979;Leathwick et al., 2006;Gordon et al., 2010;Francis et al., 2011;Morrison et al., 2014), and the sub-Antarctic Auckland Islands (Kingsford et al., 1989).
Cylix tupareomanaia is currently known from very few collected specimens and observations, which suggests that this species occurs in low abundance throughout its range, is hard to find due to its diminutive size and excellent crypsis, only occasionally occurs within SCUBA depths, or is simply rare in the regions where surveys have been conducted. These inferences are supported by the fact that representa-  Table 1. Counts and proportional measurements of type specimens of Cylix tupareomanaia. Ratios are separated by a colon and are listed as percent of SL, HL, or SnL. Abbreviations: CH (coronet height), DL (dorsal-fin length), HD (head depth), HL (head length), OD (orbital height), PL (pectoral-fin length), PO (post-orbital length), SL (standard length), SnD (snout depth), SnL (snout length), TaL (tail length), TD4 (trunk depth between the 4 th and 5 th trunk rings), TD9 (trunk depth between the 9 th and 10 th trunk rings), TrL (trunk length).

Cylix tupareomanaia
Cylix tupareomanaia Cylix tupareomanaia   Etymology.-The species epithet tupareomanaia is a neologism gifted by kaumātua (tribal elders) of Ngātiwai and references Home Point adjacent to the type locality, referred to by Ngātiwai as Tu Pare o Huia, meaning ''the plume of the huia''; the huia was a bird that became extinct in the early 20 th century. Tu Pare o Manaia translates as ''the garland of the Manaia.'' The pare, or garland, references the pentamerous head crest of the new species, and Manaia is the Māori name for a seahorse, and is also an ancestor that appears as a stylized figure used in Māori carvings representing a guardian.
Remarks.-Apparent ontogenetic differences in morphological features of the head were observed between the specimens of C. tupareomanaia examined herein (Fig. 2). The smallest female ( Fig. 2A, AIM MA122274, 31.4 mm SL, holotype) exhibits a cup-like crest on the supraoccipital that is highly elevated anteriorly, distinct median supraoccipital spine at convergence of anterior edges of the coronet, protruding well anteriorly; three dorsal spines at midline of snout on mesethmoid bones, exceptionally large principal dorsal spine at confluence with anterior continuations of supraorbital ridges, the two anterior dorsal spines small, and the lateral head spine directly ventral of the cup-like supraoccipital crest consists of distinct but small paired spines. The morphological features in the larger female paratype (Fig. 2B, NMNZ P.056154, 35.5 mm SL) are less pronounced: the median supraoccipital spine presents as a distinct but blunt spine protruding anteriorly, the snout possesses two dorsal spines, the principal spine and one small anterior spine, and the lateral head spine directly ventral of the bony pentamerous bony crest consists of small but merged paired spines. In contrast, the adult male paratype (Fig. 2C, NMNZ P.046322, 55.5 mm SL) exhibits a cup-like supraoccipital crest that is low, less elevated, angled somewhat posteriorly, and cup-like in dorsal view, the median frontal spine a minute but discernible ridge, wedge-like in appearance, one large principal spine at midline of snout, and the lateral head spine directly ventral of the pentamerous bony crest is merged as one rugose spine.

Acentronura Kaup, 1853
Diagnosis.-A genus of the Syngnathidae that shares numerous morphological synapomorphies with Cylix and Idiotropiscis, including head angled ventrally approximately 258 from the principal body axis, enclosed brood pouch, brood  Diagnosis.-See generic diagnosis. Acentronura breviperula differs from its congeners by the following combination of characters: supraoccipital consisting of a distinct bony bipartite dorsomedial crest, segments arcuate in lateral view, followed by an elevated and long bony dimple; posterior margin of second segment of dorsomedial crest merging within the bony dimple, which is approximately one-third longer than the dorsomedial crest and tapered posteriorly. Tables 2-4. Superior trunk and tail ridges discontinuous below dorsal-fin base, lateral tail ridge present, inferior trunk ridge ends at anal ring, lateral trunk ridge confluent with inferior tail ridge. Head angled ventrally 258 from the principal body axis, the anterodorsal profile slightly conoid in lateral aspect; supraoccipital low, not elevated, with a distinct bony bipartite dorsomedial crest, segments arcuate in lateral view, followed by an elevated and long bony dimple; posterior margin of second segment of dorsomedial crest merging within the bony dimple, which is approximately one-third longer than the dorsomedial crest and tapered posteriorly; bilateral bony lobed protuberances on the posterolateral margins of the post-temporal bones (Fig.  10A); anterior nuchal plate absent (Fig. 9A); posterior nuchal plate present anterior to cleithrum with dorsomedial crestlike ridge along its dorsum, large gap between the supraoccipital and posterior nuchal plate; small blunt spine midway between orbit and lobed protuberance on operculum; cleithral ring distinct, discontinuous mid-dorsally; gill slit between supraoccipital and cleithral ridge; rim of orbit projecting dorsolaterally and slightly ventrolaterally; snout spine absent; interorbital narrow, depressed; opercular ridge distinct, entire, angled dorsally toward gill opening; swelling of gular region ventroposterior to orbit absent; pectoral-fin base without distinct ridges, low, strongly elevated ventrolateral bulge supporting the pectoral-fin absent; trunk deepest anteriorly, principal body ridges distinct; principal body ridge spines absent; caudal fin absent. Acentronura breviperula exhibits strong sexual dimorphism associated with the presence of a brood pouch. The brood pouch is formed along the ventral midline of the tail and is present below the anteriormost eight tail rings (Fig. 11A).

Description.-Morphometric and meristic characters listed in
Distribution.-Acentronura breviperula is known from the tropical Indo-West Pacific, from East Africa, Madagascar, the Red Sea, Persian Gulf, Papua New Guinea, Torres Strait, northern Great Barrier Reef, Australia, New Caledonia, and Taiwan (Fraser-Brunner and Whitley, 1949;Dawson, 1985;Kuiter, 2000Kuiter, , 2003Fricke and Kulbicki, 2006;Chen, 2017;Fricke et al., 2019 Diagnosis.-See generic diagnosis. Acentronura gracilissima differs from its congeners by the following combination of characters: supraoccipital consisting of a distinct dorsomedial crest, non-segmented, ridge-like in lateral view, followed by an elevated and bony dimple; bony dimple approximately one-third in length of dorsomedial crest.  Taitokerau Tables 2-4. Superior trunk and tail ridges discontinuous below dorsal-fin base, lateral tail ridge present, inferior trunk ridge ends at anal ring, lateral trunk ridge confluent with inferior tail ridge. Head angled ventrally 258 from the principal body axis, the anterodorsal profile slightly conoid in lateral aspect; supraoccipital, low, not elevated, with a distinct dorsomedial crest, non-segmented, ridge-like in lateral view, followed by an elevated and bony dimple; bony dimple approximately one-third in length of dorsomedial   crest; bilateral bony lobed protuberances on the posterolateral margins of the post-temporal bones (Fig. 10B); anterior nuchal plate absent (Fig. 9B); posterior nuchal plate present anterior to cleithrum with dorsomedial crest-like ridge along its dorsum, large gap present between the supraoccipital and posterior nuchal plate; small blunt spine midway between orbit and lobed protuberance on operculum; cleithral ring distinct, discontinuous mid-dorsally; single gill slit between supraoccipital and cleithral ridge; rim of orbit projecting dorsolaterally and slightly ventrolaterally; snout spine absent; interorbital narrow, depressed; opercular ridge distinct, entire, angled dorsally toward gill opening; swelling of gular region ventroposterior to orbit absent; pectoral-fin base without distinct ridges, low, strongly elevated ventrolateral bulge supporting the pectoral-fin absent; trunk deepest anteriorly, principal body ridges distinct; principal body ridge spines absent; caudal fin absent. Acentronura gracilissima exhibits strong sexual dimorphism associated with the presence of a male brood pouch. The brood pouch is formed along the ventral midline of the tail and is present below the anteriormost 14 tail rings (Fig. 8B). lCT scanning of the specimen (Fig. 9B) revealed the brood pouch is enclosed by 14 arcuate bony extensions, which extend ventrolaterally from the anterior ventral plate ridges of the tail and are reduced in size posteriorly. The anteriormost pouch plate is broad and paddle-shaped at ventrocaudal margin and curved posterolaterally relative to other pouch plates. The second pouch plate appears to consist of double arcuate bony extensions merged as one bony extension. The posteriormost pouch plate is diminutive in size.
Diagnosis.-See generic diagnosis. Acentronura tentaculata differs from its congeners by the following combination of characters: supraoccipital consists of distinct bony bipartite dorsomedial crest, segments arcuate in lateral view, followed by an elevated and bony dimple; posterior margin of second segment of dorsomedial crest located at opening of, but not merged within, the bony dimple, which is approximately equal in length to the dorsomedial crest and tapered posteriorly. Tables 2-4. Superior trunk and tail ridges discontinuous below dorsal-fin base, lateral tail ridge present, inferior trunk ridge ends at anal ring, lateral trunk ridge confluent with inferior tail ridge. Head angled ventrally 258 from the principal body axis, the anterodorsal profile slightly conoid in lateral aspect; supraoccipital, low, not elevated, with a distinct bony bipartite dorsomedial crest, segments arcuate in lateral view, followed by an elevated and bony dimple; posterior margin of second segment of dorsomedial crest located at opening of, but not merged within, the bony dimple, which is approximately equal in length to the dorsomedial crest and tapered posteriorly; bilateral bony lobed protuberances on the posterolateral margins of the post-temporal bones (Fig. 10C); anterior nuchal plate absent (Fig. 9C-D); posterior nuchal plate present anterior to cleithrum with dorsomedial crest-like ridge along its dorsum, large gap present between the supraoccipital and posterior nuchal plate; small blunt spine midway between orbit and lobed protuberance on operculum; cleithral ring distinct, discontinuous mid-dorsally; single gill slit between supraoccipital and cleithral ridge; rim of orbit projecting dorsolaterally and slightly ventrolaterally; snout spine absent; interorbital narrow, depressed; opercular ridge distinct, entire, angled dorsally toward gill opening; swelling of gular region ventroposterior to orbit absent; pectoral-fin base without distinct ridges, low, strongly elevated ventrolateral bulge supporting the pectoral-fin absent; trunk deepest anteriorly, principal body ridges distinct; principal body ridge spines absent; caudal fin absent. Acentronura tentaculata exhibits strong sexual dimorphism associated with the presence of a male brood pouch. The brood pouch is formed along the ventral midline of the tail and is present below the anteriormost 12 tail rings (Fig. 8C-D). lCT scanning of the material (Fig. 9C-D) revealed the brood pouch is enclosed by 12 arcuate bony extensions, which extend ventrolaterally from the anterior ventral plate ridges of the tail and are reduced in size posteriorly. The anteriormost pouch plate is broad and paddle-shaped at ventrocaudal margin and curved posterolaterally relative to other pouch plates. The posteriormost pouch plate is diminutive in size.

Idiotropiscis Whitley, 1947
Diagnosis.-A genus of the Syngnathidae that shares numerous morphological synapomorphies with Acentronura and Cylix, including head angled ventrally approximately 258 from the principal body axis, enclosed brood pouch, brood pouch plates, prehensile tail, and absence of caudal fin. However, Idiotropiscis differs from its co-familials by the following combination of characters: supraoccipital is elevated with a distinct and raised bony dorsomedial crest; posterolateral margins of post-temporal bones expanded moderately anteriorly taking the form of protuberances; anterior nuchal plate absent; posterior nuchal plate present anterior to cleithrum with dorsomedial crest-like ridge along its dorsum, large gap present between the supraoccipital and posterior nuchal plate; small blunt spine midway between orbit and lobed protuberance on operculum; cleithral ring distinct, discontinuous mid-dorsally; bilateral gill slits situated laterally on head between supraoccipital and cleithrum.
Diagnosis.-See generic diagnosis. Idiotropiscis australe differs from its congeners by the following combination of characters: distinct raised bony multipartite dorsomedial crest on the supraoccipital, the four segments arcuate in lateral view, spanning the complete frontal from anterior margins of the interorbital to the supraoccipital, protruding anteriorly; posterolateral margins of post-temporal bones expanded moderately anteriorly taking the form of curved protuberances; small dorsal snout spine present medially on mesethmoid bone.
Description.-General body shape as in Figure 13. Morphometric and meristic characters listed in Tables 2-4. Superior trunk and tail ridges discontinuous below dorsal-fin base, lateral tail ridge present, inferior trunk ridge ends at anal ring, lateral trunk ridge confluent with inferior tail ridge. Head angled ventrally 258 from the principal body axis, the anterodorsal profile slightly conoid in lateral aspect, rising from short snout to an elevated supraoccipital; distinct raised bony multipartite dorsomedial crest on the supraoccipital, the four segments arcuate in lateral view, spanning the complete frontal from anterior margins of the interorbital to the supraoccipital, protruding anteriorly; posterolateral margins of post-temporal bones expanded moderately anteriorly taking the form of curved protuberances (Fig. 14A); anterior nuchal plate absent (Fig. 13A); posterior nuchal plate present anterior to cleithrum with dorsomedial crest-like ridge along its dorsum, large gap present between the supraoccipital and posterior nuchal plate; small blunt spine midway between orbit and lobed protuberance on operculum; cleithral ring distinct, discontinuous mid-dorsally; gill openings as small bilateral slits directly situated laterally on head between supraoccipital and cleithrum; small dorsal snout spine present medially on mesethmoid bone; interorbital narrow, depressed; opercular ridge low, entire, angled dorsally toward gill opening; slight swelling of gular region ventroposterior to eye; pectoral-fin base without distinct ridges, on strongly elevated ventrolateral bulge; trunk deepest anteriorly, principal body ridges distinct; principal body ridge spines absent. Caudal fin absent. Idiotropiscis australe exhibits strong sexual dimorphism associated with the presence of a male brood pouch. The brood pouch is formed along the ventral midline of the tail and is present below the anteriormost 11 tail rings (Fig.  12A). lCT scanning of the material (Fig. 13A) revealed the brood pouch is enclosed by 11 arcuate bony extensions, which extend ventrolaterally from the anterior ventral plate ridges of the tail and are reduced in size posteriorly. The anteriormost pouch plate is broad and paddle-shaped at ventrocaudal margin and curved posterolaterally relative to other pouch plates. The posteriormost pouch plate is diminutive in size.
Distribution.-Idiotropiscis australe is endemic to the temperate waters of southern and southwestern Australia, from   Cape Jarvis and the Gulf St Vincent, South Australia, and Carnac Island, Western Australia (Dawson, 1985 Diagnosis.-See generic diagnosis. Idiotropiscis larsonae differs from its congeners by the following combination of characters: bony dorsomedial crest on the supraoccipital, strongly elevated, tripartite, the three large segments arcuate in lateral view, spanning the complete frontal from anterior margins of the interorbital to the supraoccipital, compressed laterally, protruding anteriorly; posterolateral margins of post-temporal bones expanded slightly anteriorly taking the form of flat protuberances, not prominent; rim of orbit projecting slightly dorsolaterally and ventrolaterally; small dorsal snout spine present medially on mesethmoid bone; body compressed laterally. Tables 2-4. Superior trunk and tail ridges discontinuous below dorsal-fin base, lateral tail ridge present, inferior trunk ridge ends at anal ring, lateral trunk ridge confluent with inferior tail ridge. Head angled ventrally 258 from the principal body axis, the anterodorsal profile slightly conoid in lateral aspect; bony dorsomedial crest on the supraoccipital, strongly elevated, tripartite, the three large segments arcuate in lateral view, spanning the complete frontal from anterior margins of the interorbital to the supraoccipital, compressed laterally, protruding anteriorly; posterolateral margins of post-temporal bones expanded slightly anteriorly taking the form of flat protuberances, not prominent and difficult to discern (Fig. 14B); anterior nuchal plate absent; posterior nuchal plate present anterior to cleithrum with dorsomedial crest-like ridge along its dorsum, large gap present between the supraoccipital and posterior nuchal plate; small blunt spine midway between orbit and lobed protuberance on operculum; cleithral ring distinct, discontinuous mid-dorsally; bilateral gill slits situated laterally on head between supraoccipital and cleithrum; median dorsal snout spine present on mesethmoid bone; interorbital narrow, depressed; rim of orbit projecting moderately dorsolaterally and ventrally; opercular ridge low, entire, angled dorsally toward gill opening; swelling of the gular region ventroposteriorly of eye absent; pectoral-fin base without distinct ridges, low, strongly elevated ventrolateral bulge supporting the pectoral-fin base absent; trunk compressed laterally, span of dorsum of pre-dorsal trunk rings less by half of dorsum of anterior post-dorsal tail rings, span of trunk at lateral and inferior ridges somewhat greater than span of dorsum of trunk; subdorsal rings four (spans three trunk rings and one tail rings vs. two trunk rings and two tail rings in paratype); principal body ridges distinct; superior tail ridge with slightly enlarged spines on 4 th , 12 th , and 16 th trunk rings. Caudal fin absent. Idiotropiscis larsonae exhibits strong sexual dimorphism associated with the presence of a brood pouch in the male (Figs. 11C, 12B). The brood pouch is formed along the ventral midline of the tail and is present below the anteriormost nine tail rings. X-ray image of the holotype revealed the brood pouch is enclosed by nine arcuate bony extensions and reduced in size posteriorly. The female paratype exhibits well-developed ossification of the skeleton, including the strong ossification of the inferior and ventral trunk area as detected by lCT scanning (Fig. 13B).
Diagnosis.-See generic diagnosis. Idiotropiscis lumnitzeri differs from its congeners by the following combination of characters: strongly elevated supraoccipital; large, prominent, and raised bony dorsomedial crest on the supraoccipital, dome-like in lateral view, protruding anteriorly; posterolateral margins of post-temporal bones expanded moderately anteriorly taking the form of tapered and winglike protuberances; rim of orbit projecting dorsolaterally; one large and blunt spine on cleithral at level of last pectoral-fin ray; small spine posterolateral to pectoral fin; superior trunk ridge with enlarged spines projecting dorsolaterally on 6 th and 10 th trunk rings; subdorsal spines four, last two superior trunk ridges ending under dorsal fin with subdorsal spines, first two superior tail ridges under dorsal fin with subdorsal spines.
Description.-Morphometric and meristic characters listed in Tables 2-4. Superior trunk and tail ridges discontinuous below dorsal-fin base, lateral tail ridge present, inferior trunk ridge ends at anal ring, lateral trunk ridge confluent with inferior tail ridge. Head large relative to body, angled ventrally 258 from the principal body axis, the anterodorsal profile conoid in lateral aspect; rising steeply from short snout to a prominent supraoccipital; large, prominent, and raised bony dorsomedial crest on the supraoccipital, domelike in lateral view, dorsocaudal margin irregular, protruding anteriorly; posterolateral margins of post-temporal bones expanded moderately anteriorly taking the form of tapered and wing-like protuberances (Fig. 14C); cleithral ring distinct, prominent, discontinuous mid-dorsally; anterior nuchal plate absent; posterior nuchal plate present anterior to cleithrum with dorsomedial crest-like ridge along its dorsum, large gap present between the supraoccipital and posterior nuchal plate; cleithral ring distinct, low, discontinuous middorsally at bony dorsomedial crest; rim of orbit projecting dorsolaterally; opercular ridge low, entire, angled dorsally toward gill opening; swelling of gular region ventroposterior to eye forming a transverse pair of blunt protuberances; pectoral-fin base without distinct ridges, on strongly elevated ventrolateral bulge (Fig. 15); trunk narrowest at 3 rd and 4 th ring; dorsum of 2 nd , 3 rd , and 4 th trunk rings noticeably broader than 5-11 th trunk rings; dorsal-fin base strongly raised dorsally; subdorsal rings four (spans two and a half trunk rings and one and a half tail rings), dorsal-fin base starting immediately posterior to 10 th trunk ring and ending immediately posterior to 2 nd tail ring; caudal fin absent. Body spines: large spine present on cleithral ring at level of last pectoral-fin ray (Fig. 15A); small spine present posterolateral to the pelvic fin (Fig. 15A); superior trunk ridge with enlarged spines projecting dorsolaterally on 6 th and 10 th trunk rings; subdorsal spines four, last two superior trunk ridges ending under dorsal fin with subdorsal spines, first two superior tail ridges under dorsal fin with subdorsal spines (Fig. 15B); large simple and branched dermal flaps present on anterior part of frontal ridge, ventral to eye, 4 th and 7 th superior trunk ridges, 7-9 th lateral and inferior trunk ridges, and on 5 th , 10 th , 15 th , 19 th , and 24 th superior and inferior tail ridges. The female specimen (AMS I.45395-001) exhibits well-developed ossification of the skeleton, including the strong ossification of the inferior and ventral trunk area as detected by lCT scanning (Fig. 13D). Idiotropiscis lumnitzeri exhibits strong sexual dimorphism associated with the presence of a male brood pouch. The brood pouch is formed along the ventral midline of the tail and is present below the anteriormost 11 tail rings (Fig. 12D). lCT scans revealed the brood pouch is enclosed by 11 arcuate bony extensions (Figs. 13C, 15B), which extend ventrolaterally from the anterior ventral plate ridges of the tail, are reduced in size posteriorly, the anteriormost extension and curved posterolaterally relative to the other extensions.
Distribution.-Idiotropiscis lumnitzeri is endemic to the temperate waters of southeastern Australia, from Cabbage Tree Bay, Manly, to Brush Island located south of Ulladulla Harbour, New South Wales (Kuiter, 2004

DISCUSSION
All previous descriptions of pygmy pipehorses are based only on one or two specimens in which the internal (skeletal) anatomy of the described species was undocumented. (e.g., Temminck and Schlegel, 1850;Günther, 1870;Waite and Hale, 1921;Fraser-Brunner and Whitley, 1949;Dawson, 1984;Kuiter, 2004). Our description of C. tupareomanaia is also derived from a small number of individuals (holotype and two paratypes), but contrary to these previous descriptions, we have observed elements in the skeleton of C.
tupareomanaia using micro-computed tomography from which we have identified key diagnostic features, especially of the neurocranium (see diagnosis). The morphological details would have been impossible to obtain from traditional radiographs alone.
Comparative morphological studies among pygmy pipehorses.-Cylix tupareomanaia and members of Acentronura and Idiotropiscis (Figs. 10-17), despite being superficially similar in outward appearance, exhibit significant morphological differences among them in the neurocranium that aid in their diagnoses. The main neurocranial distinctions were observed in the morphology of the supraoccipital crests and bilateral bony lobed protuberances on the posterolateral margins of the post-temporal bones. The characters that distinguish Cylix tupareomanaia from the members of Idiotropiscis are presented in Tables 2-5 and summarized below. Cylix tupareomanaia is unique in Syngnathidae in possessing a highly derived bony cup-like crest present anterodorsally on the supraoccipital and large, conspicuous conical spines ventrally centered on the head on the cleithral symphysis and the first trunk ring between the pectoral-fin bases, which we propose as apomorphies for this species. Cylix tupareomanaia is most similar to members of Idiotropiscis (Tables 2-4) in meristic and morphometric characters and in the following morphological and neurocranial characters: principal ridge configuration; elevated supraoccipital; absence of anterior nuchal plate presence of posterior nuchal plate, with large gap between it and the supraoccipital; presence of a bony dorsomedial crest on the dorsum of the posterior nuchal plate; pronounced ventrolateral bulge supporting the pectoral-fin base; and certain body spines (snout spines in I. australe and I. larsonae; four subdorsal spines, large cleithral ring spine at level of last pectoral-fin ray, and small spine present posterolateral to the pelvic fin in I. lumnitzeri [ Fig.  14]). Cylix tupareomanaia differs primarily from the members of Idiotropiscis by features of the crest morphology on the supraoccipital bone (cup-like pentamerous crest  vs. the presence of a thin bony dorsomedial crest ) and large midventral spines on the cleithral symphysis and the first trunk ring between the pectoral-fin bases (Figs. 4-6; vs. absence of midventral spines and presence of flat surface venter of head and first trunk ring 15]). Additional distinguishing characters include the absence of bilateral bony lobed protuberances on the posterolateral margins of the post-temporal bones (vs. presence in all members of Acentronura and Idiotropiscis [Figs. 12,16]), the presence of the supracleithrum that extends dorsally from the cleithrum, forming a continuous bony collar (Fig. 5) vs. absence of a supracleithrum resulting in cleithra terminating at the anterior margins of the bony dorsomedial crest [Figs. 10,13,14]), bony spines (on the snout, frontal, ventrolateral surface of head, upper and lower cleithral ring, subdorsal ridges, and principal trunk and tail ridges  vs. absence of spines except on the snout in I. australe and I. larsonae 15]; four subdorsal spines, large cleithral ring spine at level of last pectoral-fin ray, and small spine present posterolaterally of the pelvic-fin base in I. lumnitzeri      The morphologically similar members of Acentronura (Figs. 8-9) share a number of characteristics of the head with Cylix and Idiotropiscis, including: the absence of anterior nuchal plate, presence of posterior nuchal plate, with large gap between it and the supraoccipital; presence of the bony dorsomedial crest on the posterior nuchal plate; and fully enclosed male brood pouch enfolded by 7, 14, and 12 pouch plates in A. breviperula, A. gracilissima, and A. tentaculata, respectively (vs. 10 in C. tupareomanaia and 9-11 in Idiotropiscis [ Table 4]). Acentronura can be distinguished by the slim trunk (vs. deep trunk), continuous superior trunk ridge (vs. discontinuous), low supraoccipital (vs. elevated supraoccipital), distinct and low dorsomedial bony crest followed by a raised bony dimple on the supraoccipital (vs. prominent dorsomedial bony crest protruding anteriorly in Idiotropiscis; and large cup-like pentamerous crest protruding anteriorly in C. tupareomanaia), presence of bilateral bony lobed protuberances on the posterolateral margins of the post-temporal bones (vs. present in Idiotropiscis; absent in C. tupareomanaia); absence of body spines (vs. snout spines in I. australe and I. larsonae; four subdorsal spines, large cleithral spine at level of last pectoral-fin ray, and small spine present posterolaterally on the pelvic-fin base in I. lumnitzeri; and spines on snout, frontal, ventrolaterally of head, upper and lower cleithral ring, subdorsal ridges, and principal trunk and tail ridges in C. tupareomanaia), number of tail rings (43 vs. 37 in I. australe, 39-40 in I. larsonae, 43 in I. lumnitzeri; 35-36 in C. tupareomanaia [Tables 3, 4]), and the number of tail rings spanning the male brood pouch (14 vs. 11 in I. australe, 9 in I. larsonae, 11 in I. lumnitzeri; 8 in C. tupareomanaia [ Table 4]). The anteriormost pouch plate is broad and paddle-shaped at the ventrocaudal margin and curved posterolaterally relative to the other plates, which are uniform in shape, in A. gracilissima, A. tentaculata, I. australe, and I. lumnitzeri (vs. all uniform in shape in C. tupareomanaia; unknown in A. breviperula and I. larsonae). The brood pouch is further distinguished in A. gracilissima by the first and second anteriormost pouch plates, which appear to be large and bifurcated ventrolateral extensions (Fig. 9B). Additionally, the congener A. breviperula shares the fully enclosed male brood pouch enfolded by arcuate ventrolateral bony extensions (Fig. 12, Table 4).
Morphological comparisons to seahorses.-Cylix and Idiotropiscis are superficially similar in appearance to members of Hippocampus and share with the latter numerous morphological synapomorphies, including meristic characters, an elevated frontal and supraoccipital, principal trunk ridge configuration, elevated dorsal-fin base, head angled ventrally relative to the principal body axis (258 vs. 908 in seahorses), moderately deep trunk (vs. slender trunk in Acentronura), male brood pouch, prehensile tail, and absence of a caudal fin. Cylix tupareomanaia, in particular, exhibits seahorse-like characteristics, including head and principal body ridge spines present on the snout, frontal, cleithral ring, and subdorsal area, and a highly derived supraoccipital crest present anterodorsally on its head that is remarkably similar in outward appearance to the distinct coronet present in most species of Hippocampus (Fig. 16, Table 5). In 2006, the first photographic record of C. tupareomanaia, observed in coralline and red algae at 10 m depth, was taken at Tawhiti Rahi, the Poor Knights Islands, Northland, New Zealand (Kuiter, 2009: 93, figs. A, B). However, the female individual in the photograph was originally misidentified as the subtropical Southwest Pacific seahorse, Hippocampus jugumus Kuiter, 2001, due to a superficial similarity in external appearance to this species (e.g., slender body, distinct coronet, continuous cleithral ring, and meristic characters) and therefore at the time mis-recorded as a range extension from its type locality of Lord Howe Island, NSW, Australia to temperate New Zealand. Hippocampus jugumus has since been collected from New Zealand waters, at the offshore subtropical Rangitāhua Kermadec Islands in the northernmost region of New Zealand (Clark et al., 2017).
Despite the similarity between Cylix and Hippocampus, a suite of anatomical features of the head and first trunk ring (Fig. 16, Table 5) readily distinguish Cylix from Hippocampus, including: anterior nuchal plate absent (vs. present in the modified form of a coronet in Hippocampus between the supraoccipital and the posterior nuchal plate); the elevated supraoccipital well separated from the cleithrum above the operculum, forming a large gap between the two areas (vs. supraoccipital and anterior and posterior nuchal plates interdigitated dorsally and connected lateroventrally by the cleithrum); distinct coronet present but derived from the cup-like and divided pentamerous bony crest on the supraoccipital bone (vs. derived from the modified anterior nuchal); presence of dorsomedial bony crest on the posterior nuchal plate (vs. absence); cleithrum reaches mid-dorsally over anterior margins of bony dorsomedial crest (vs. ventrally on a projected horizontal line through gills in members of Hippocampus with the exception of H. jugumus [Kuiter, 2001] and the pygmy seahorse species H. japapigu, H. pontohi, H. satomiae, and H. waleananus [Short et al., 2018]); snout spines present on the mesethmoid and angled dorsally (vs. present directly anterior of the interorbital space and angled anteriorly); elevated rim of orbit protruding dorsally and ventrally (vs. no elevation of rim of orbit); eye spines absent (vs. presence of spines dorsally and ventrally of eye); strongly elevated ventrolateral bulge on first trunk ring supporting the pectoral fin (vs. absence of ventrolateral bulge on first trunk ring); and male brood pouch plates present (vs. absent).
Genetic analyses performed here using the nuclear gene sequences TMO-4C4 and 18S, and retrieved with ML, MP, and MrBayes (Fig. 17), resulted in well-supported topologies concordant with the hypothesized clade Vi of Hamilton et al. (2017). The pygmy pipehorse genera Cylix, Idiotropiscis, and Acentronura form a monophyletic group with strong support in which C. tupareomanaia is placed as sister group to a clade comprising Acentronura and Idiotropiscis. Together, the three genera form the sister group to a clade comprising the Indo-Pacific pipefish genera Filicampus, Haliichthys, Lissocampus, and Trachyrhamphus, all of which are endemic or occur in Australia and New Zealand. All of these aforementioned genera together form a clade representing the sister group to Hippocampus. The placement of C. tupareomanaia in clade Vi further supports the refutation by Hamilton et al. (2017) of the immediate sister taxon relationship between Hippocampus and the pygmy pipehorses hypothesized by Teske and Beheregaray (2009).

DATA ACCESSIBILITY
The tree file for the phylogenetic hypothesis associated with this work (Fig. 17) is available at https://www. ichthyologyandherpetology.org/i2020136. Unless an alternative copyright or statement noting that a figure is reprinted from a previous source is noted in a figure caption, the published images and illustrations in this article are licensed by the American Society of Ichthyologists and Herpetologists for use if the use includes a citation to the original source (American Society of Ichthyologists and Herpetologists, the DOI of the Ichthyology & Herpetology article, and any individual image credits listed in the figure caption) in accordance with the Creative Commons Attribution CC BY License. ZooBank publication urn:lsid:zoobank.org: pub:DD96034D-06EC-4FA5-9E68-B128195F88D3. Table 6. Uncorrected genetic distances (p-distances) summary between C. tupareomanaia and species of Acentronura and Idiotropiscis based on cytochrome c oxidase I (COI) sequences analyzed in this study.