Cylix nkosi, Short & Smith & Harasti & Claassens, 2024

Cylix nkosi , new species urn:lsid:zoobank.org:act:A645A185-D9E1-42B2-9347-FBA8BAA9EE26

Common Name: Sodwana Pygmy Pipehorse

Figures 1–9 View FIG View FIG View FIG View FIG View FIG View FIG View FIG View FIG View FIG ; Tables 1–3

Holotype.— SAMC F041935 View Materials , 45.9 mm SL, female, 2 Mile Reef , Sodwana Bay, KwaZulu-Natal, South Africa, 27 8 30 0 46.6 00 S, 32 8 41 0 10.4 00 E, 22 m depth, 18 October 2018, L. Claassens, R. Smith, scuba diving.

Paratype.— SAIAB 39737 About SAIAB , 46.6 mm SL, male, the mouth of the Kosi River , Kosi Bay, KwaZulu-Natal, South Africa, 26 8 53 0 54.0 00 S, 32 8 55 0 30.0 00 E, field station ZA 10 , R. V. Meiring Nande, trawl, 50 m depth, 7 June 1987 .

Diagnosis.— Cylix nkosi differs from C. tupareomanaia in possessing a supraoccipital bone bearing a highly derived and distinct diamond-shaped bony protuberance (SP; vs. cup-like bony protuberance; Table 3) oriented anteriorly, rhombus-shaped in anterodorsal view, divided transversally into two sections by a ridge; knob-shaped midventral spine (CSS; vs. udder-shaped bony protuberance; Table 3) on the cleithral symphysis; blunt midventral spine (MVFTRS; vs. conical midventral spine; Table 3) on the first trunk ring between the pectoral-fin bases; thick dorsomedial crest-like ridge (FTRC; vs. thin and rugose crest-like ridge; Table 3) extending over the length of the first trunk ridge; median frontal spine (FS) at convergence of anterior edges of the supraoccipital bone, anterior margin straight-edged; rugose double lateral head spine (DHS) present below supraoccipital v; three supraorbital extensions or spines (ORE), anterior two a double spine and equal in size, the posteriormost spine large and oblong in shape. The following characters are also diagnostic, although not unique to the species: cleithrum continuous middorsally; supracleithrum present; anterior and posterior nuchal plates absent, large gap present between the supraoccipital and cleithrum; small blunt midlateral spines proximally on operculum; two oval-shaped spines on cleithral ring, one spine (CS1) present on anterior to ventral third of pectoral-fin base, the second spine (CS2) present at the ventral extent of the head; small spine (PLS) present posterolaterally on the pelvic-fin base; four subdorsal spines, forming a square, the dorsal two enlarged, the ventral two small in size.

Description.— Meristic and morphometric characters for the type specimens are listed in Table 1. Superior trunk and tail ridges discontinuous below dorsal-fin base, lateral tail ridge present, inferior trunk ridge ends at the anal ring, lateral trunk ridge confluent with the inferior tail ridge. Body slender; head large relative to body, angled ventrally approximately 25 8 from the principal body axis, the dorsal profile pyramidal in lateral aspect, rising steeply from snout to elevated and prominent supraoccipital bone; supraoccipital bone bearing a highly derived and distinct diamond-shaped bony protuberance (SP) oriented anteriorly well behind the eye, rhombus-shaped in anterodorsal view, divided transversally into two sections by a ridge ( Figs. 6–9 View FIG View FIG View FIG View FIG ; referred to as the supraoccipital crest in Short and Trnski, 2021); cleithrum continuous middorsally; supracleithrum present; anterior and posterior nuchal plates absent (though overlooked by Short and Trnski, 2021 in their description of C. tupareomanaia due to the highly derived morphology of the neurocranial bones, we now note the absence of the posterior nuchal plate represents a synapomorphy of Cylix ); diamond-shaped bony protuberance on supraoccipital equal in height to cleithrum, forming a large gap between the two bones; thick dorsomedial crest-like ridge present on the first trunk ridge (FTRC) directly behind the cleithrum; gill opening anterior to and supported by the cleithrum; rim of orbit elevated dorsolaterally and strongly ventrally, fluted with rugose sculpturing; opercular ridge low, 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 on a strongly elevated ventrolateral bulge; dorsal-fin origin on 12 th trunk ring, fin base elevated; 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.

Enlarged spine (SnS1) 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; two small middorsal spines (SnS2, SnS3) on the mesethmoid bone anterior to the enlarged spine on the snout; three supraorbital extensions or spines (ORE), the anterior two spines a merged double spine and equal in size, the posteriormost spine large and oblong in shape; distinct median frontal spine (FS) at convergence of anterior edges of the supraoccipital bone, protruding forward, anterior margin of spine straight-edged; lateral head spines present, rugose double lateral head spine (DHS) directly below the supraoccipital protuberance, small blunt midlateral spines proximally on operculum; knob-shaped midventral spine (CSS) on the cleithral symphysis; blunt midventral spine (MVFTRS) on the first trunk ring between the pectoral-fin bases ( Figs. 2 View FIG , 7 View FIG , 9 View FIG ); two oval-shaped spines on cleithral ring, moderate-sized spine (CS1) anterior to ventral third of pectoral-fin base, large lobe-shaped spine (CS2) at ventral extent of head; small spine present (PLS) posterolaterally on the pectoral-fin base ( Figs. 2 View FIG , 7 View FIG ); superior trunk ridge spines absent; lateral trunk ridges with small blunt spines on each trunk ridge starting at the 2 nd trunk ridge; inferior trunk ridges with small blunt spines starting on the 2 nd trunk ridge; subdorsal spines four, superior trunk ridge ending with two prominent subdorsal spines, superior tail ridge commencing with two small reduced subdorsal spines, in alignment with larger subdorsal spines above; superior tail ridge spines absent.

of single bony extensions. The posteriormost pouch plate diminutive in size.

Coloration.— Holotype in life ( Fig. 3 View FIG ), head, trunk, and tail reddish brown; ventrolateral margin of trunk brown; dorsum of head speckled with translucent red dots; snout white. Thin red filaments are present on the dorsum of the trunk. Other individuals of C. nkosi observed at the type location exhibit background coloration uniformly solid red, mustard yellow, or light brown, respectively ( Fig. 4A–D View FIG ), which apparently relates to the coloration of local sessile invertebrate growth. In alcohol, the holotype is dark brown in coloration ( Fig. 1 View FIG ). Fins hyaline. Coloration of preserved paratype in Figure 1 View FIG . Specimen lacks pigment in head, trunk, and tail, light tan in coloration.

Male paratype SAIAB 39737 exhibits brood pouch dimorphism ( Figs. 1 View FIG , 4 View FIG , 6 View FIG ). Brood pouch positioned along the ventral midline of the tail below the anteriormost six tail rings. It is enclosed by six arcuate bony pouch plates ( Fig. 6 View FIG ), which extend ventrolaterally from the anterior ventral plate ridges of the tail, progressively reducing in size posteriorly. Second to fifth brood pouch plates consist of double arcuate bony extensions merged into one bony extension. Anterior- and posteriormost pouch plates consist Distribution and habitat.— Cylix nkosi is currently recorded from two locations in KwaZulu-Natal, South Africa: Sodwana Bay and Kosi Bay ( Fig. 5 View FIG ). These two sites are situated within the boundaries of the iSimangaliso Wetland Park, a UNESCO World Heritage Site that extends from Lake St Lucia in the south to the Mozambique border in the north, encompassing the north coast of the KwaZulu-Natal province. The new species likely has a wider distribution along the tropical Indian Ocean coast of East Africa and remains undetected, perhaps attributable to its cryptic behavior and diminutive size, low abundance throughout its range, a rarity in the regions where surveys have been conducted, or misidentification as members of Acentronura or Hippocampus . Future ichthyofaunal surveys, as well as observations by recreational scuba divers, may confirm its occurrence in northern regions such as Mozambique, Tanzania, Kenya, and offshore areas towards Madagascar.

Africa’s southernmost coral reefs are situated in northern KwaZulu-Natal Province, South Africa, which are dominated chiefly by soft coral and branching stony corals of the genus Acropora and Pocillopora ( Riegl et al., 1996; Schleyer and Celliers, 2002, 2003; Schleyer et al., 2005, 2008; Porter and Schleyer, 2017, 2019; Schleyer and Porter, 2018). The coast of KwaZulu-Natal is regularly subjected to open ocean and episodic storm swells that cause the breakage and dislodgement of these stony corals ( Riegl et al., 1996; Schleyer and Porter, 2018; Porter and Schleyer, 2019). At the type locality in Sodwana Bay, the marine ecosystem consists of flat sandstone-based coral reefs in addition to unique topographic features comprising low pinnacles, shallow drop-offs, and sandy gullies ( Ramsay, 1994). The holotype and other observed individuals of C. nkosi in situ ( Fig. 4A–D View FIG ) were observed in protected sandy basins in otherwise exposed areas with accumulated debris near flat rocky reefs and observed loosely associating with sandy worm casts, sponges, and small octocorals ( Fig. 4 View FIG ), using the sessile invertebrates as a holdfast for their prehensile tails. The holotype was not observed in close proximity to other individuals of C. nkosi at the time of collection, although their cryptic nature may have prevented other individuals from being observed.

Etymology.— The species epithet is derived from the Nguni or Zulu term for chief due to the crown-like nature of the highly derived bony protuberance on the supraoccipital bone. A noun in the genitive. New English Names: Sodwana Pygmy Pipehorse is proposed here for Cylix nkosi .