Trachelochismus A new species of the clingfish genus Trachelochismus from bay and estuarine areas of New Zealand (Teleostei: Gobiesocidae) King, Cragen Zootaxa 2017 2017-09-13 4319 3 531 549 , Estuary Clingfish Estuary Clingfish [151,668,1121,1147] Actinopterygii Gobiesocidae Trachelochismus Animalia Gobiesociformes 3 534 Chordata species aestuarium  Estuary Clingfish   Figs. 2, 3, 4A,B, 5A,B, 6    Trachelochismussp.; Stewart (2015:1543, couplet 12, Fig. 24)     Holotype. NMNZP.057566, 24.0 mm SL; New Zealand, Northland, Ngunguru Riverestuary at Ngunguru, 1–2 meters depth, 35°37.78'S 174°30.41'E, 0  9 March 2016, I. Middleton, K. W. Conway, S. Hannam, G. Short, T. Trnski.    Paratypes.All New Zealand. North Island:  Auckland: AIM MA451, 2, 29.1–35.0 mm SL; Waitemata Harbour, Papakohatu (Crusoe) Island, 36°49'0.0"S 174°58'0.0"E, 0  4 May 1931.—  AIM MA3082, 1,  37.4mmSL; Whangateau Harbourbetween Emu Pointand Motuihe Islandwharf, 36°48'30"S 174°55'36"E, 0  3 July 1979.—  AIM MA4968, 2, 26.8–27.8mm SL; Whangateau Harbour, near entrance to Omaha River, 0–2 meters depth,  20 June 1982.—AIM MA76154, 1, 24.0 mm SL; Waitemata Harbour, Emu Point, 36°47'49.0"S 174°54'44.1"E, 24 March 1933.—  AIM MA30483, 1,  39.1mmSL; Hauraki Gulf, Buckland Beach at Tamaki Estuary, 36°52'00.0"S 174°54'04.3"E,  October 2011.—  AIM MA80711, 2, 23.2–29.2mm SL; Waitemata Harbourbetween Motuiheand Motutapu, 18 meters depth, 36°46'44"S 174°57'48"E,  28 March 1930.—  NMNZP.008053, 2, 41.3–42.5 mmSL; Fairchild Island, North Auckland; 36°26.00'S, 175°47.00'E,  October 1955.   Bay of Plenty: NMNZP.  012187, 1, 13.7 mmSL; off south end of Motiti Island, 16–20 meters depth, 37°40.30'S, 176°22.70'E, R/V  Tangaroa,Stn. NZOI BS738/R96,  21 January 1979.—  NMNZP.047977, 12, 21.8–31.8 mmSL; Whangapoua Harbour, East Coromandel,  Zostranear mangroves, 36°45.00'S, 175°38.00'E,  16 April 2002.   MarlboroughSounds: NMNZP.024704, 1, 24.3 mmSL; Off Cone Island, D'Urville Island, 15 meters depth, 40°55.30'S, 173°46.20'E,  27 February 1990.   Northland: AIM MA77653, 1,  22.7mmSL; Parengarenga Harbour, Parenga Channel 400 meters west of Ngamungu Point,  1 meterdepth,  17 October 1992.—  AIM MA80328, 1,  21.3mmSL; Parengarenga Harbourbetween Te Pua Pointand Dog Island, 0.3 meters depth, 34°31'30"S 172°56'48"E,  17 October 1993.— AIM MA 122277, 6 (2C&S), 25.3–34.0 mm SL; Tauranga Port, 26 March 2015.—AIM MA38045, 1, 30.0 mm SL;  TCWC 17172.01, 2, 11.3–24.9mm SL; same locality as holotype,  14 February 2015.—AIM MA143002, 4, 16.2– 21.6 mmSL; AIM MA 121550, 2, 18.0– 20.5 mmSL; TCWC 17266.03, 2 (1 SEM), 24.6 mmSL; same as holotype.—  NMNZP.008091, 1, 21.9 mmSL; Tauranga Harbour, 37°39.00'S, 176°05.00'E, on  Zostramudflats,  August 1956.—  NMNZP.009927, 1, 32.9 mmSL; off Ranganui Bay, rock dredge, 25 meters depth, 34°48.400'S, 173°19.50'E, R/V  Tangaroa,Stn. NZOI BS870/O161,  27 January 1981.—  NMNZP.009933, 6, 10.4–19.9 mmSL; off Spirits Bay, 29 meters depth, 34°25.00'S, 172°46.60'E, R/V  Tangaroa,Stn. NZOI BS916/O662,  3 February 1981.—  NMNZP.009934, 42, 10.1–24.6; off Spirits Bay, 23 meters depth, 34°25.60'S, 172°48.200'E, R/V  Tangaroa,Stn. NZOI BS915/O661, 0  3 February 1981.—  NMNZP.009935, 1, 14.5 mmSL; off Ranganui Bay, 23 meters depth, 34°49.60'S, 173°15.00'E, R/V  Tangaroa,Stn. NZOI BS871/O617,  27 January 1981.—  NMNZP.  012194, 4, 22.5–32.9 mmSL; off Ranganui Bay, 25 meters depth, 34°48.40'S, 173°19.50'E, R/V  Tangaroa,Stn. NZOI BS870/O616l,  27 January 1981.—  NMNZP.024564, 5, 22.6–31.6 mmSL; Hope Passage( Albert Channel), between Rawhiti Pointand Cable Bay, 4–6 meters depth, 35°13.00'S, 174°15.00'E,  22 October 1983.—  NMNZP.025328, 1, 30.7 mmSL; Off Ranganui Bay, 23 meters depth, 34°49.60'S, 173°15.00'E, R/V  Tangaroa,Stn. NZOI BS871/O617,  27 January 1981.—  NMNZP.025676, 4, 13.4–25.2 mmSL; Whangarei Heads, 35°49.00'S, 174°30.00'E.—  NMNZP.049305, 1, 20.7 mmSL; Whangarei Harbour, channel NW of Darch Point, 5–7 meters depth, 35°48.90'S, 174°28.80'E, 0  3 April 1997. —  NMNZP.057565, 1, 16.4 mmSL; Estuaryat Matapouribelow eastern road bridge, 35°34.21'S, 174°30.69'E, 0  2 February 2015.—  NMNZP.057565, 1, 21.3 mmSL; Sandspit side of the Ngunguru Riverestuary, 0 meters depth, 35°37.98'S, 174°30.35'E, 0  7 January 2015.   Waikato: NMNZP.049204, 1, 29.4 mmSL; Tairua Harbour, 37°00.52'S, 175°51.17'E,  21 February 2001.   Wellington: NMNZP.008060, 2, 22.0– 31.3 mmSL;  WellingtonHarbour, midway between Ward Islandand Eastbourneshore,  4 meterdepth, 41°15.00'S, 174°52.00'E, Stn. VUWR/ V Tirohia, BS272,  18 March 1971.—  NMNZP.008062, 1, 40.2 mmSL; Foveaux Strait, between Stewart Islandand Bluff, 46° 32.00'S, 167°46.00'E, 0  4 November 1970.—  NMNZP.008064, 1, 38.9 mmSL; Foveaux Strait, between Stewart Islandand Bluff, 46°32.00'S, 167°46.00'E, 0  4 November 1970.—  NMNZP.053660, 1, 45.5 mmSL; Off Days Bay, Eastbourne, 17–20 meters depth, 40°16.95'S, 174°54.00'E.—  NMNZP.049250, 4, 18.0– 31.1 mmSL; Pauatahanui Estuary, Porirua Harbour, low tide channel, amongst  Ulva, hand net0–1 meters depth, 41°06.00'S, 174°54.00'E.  South Island:  Otago: AIM MA6949, 1,  29.2mmSL;  OtagoHarbour, Portobello Bay, 4-5 meters depth, 45°50'00.0"S, 170°39'54.0"E, 0  6 January 1988.—  NMNZP.008058, 1, 28.4 mmSL; Portobello, OtagoPeninsula; 45°50.00'S, 170°39.00'E,  13 August 1962.—  NMNZP.  012302, 1, 22.8 mmSL; Portobello, OtagoPeninsula, 15 meters depth, 45°50.00'S, 170°39.00'E, 0  9 November 1952.—  NMNZP.054768, 1, 32.7 mmSL; Portobello Bay, OtagoPeninsula,  1 meterdepth, 45°49.38'S, 170°39.74'E NIWA Stn. SVDUD2287, 0  5 August 2003.   Tasman: NMNZP.008065, 1, 25.4 mmSL; Puponga, North-west Nelson; 40°31.00'S, 172°44.00'E;  5–11 m; FM Climo,  10 Mar 1971.   Diagnosis.A species of  Trachelochismusdistinguished from its congeners by the following combination of characters: adhesive disc region A without flattened papillae at centre; apapillate area of adhesive disc region A equal in width or wider than region C; flap along posterior margin of anterior nostril a short, thin blade; lachrymal canal pores 2 and 3 flush with surface of skin or weakly elevated above skin; suborbital, mandibular and postorbital rows of superficial neuromasts located in shallow grooves with smooth borders; suborbital row continuous, extending along ventral margin of orbit; postorbital row with 3 superficial neuromasts; a single gill raker along the anterior edge of ceratobranchial 1; 8 dorsal-fin rays; 7 anal-fin rays; 25 pectoral-fin rays; 32 vertebrae (14 + 18); in life, a single dark brown or black irregular streak on lateral surface of head posterior to eye.   Description.General body shape as in Figure 2. Morphometric characters listed in Table 2. Head large, slightly dorsoventrally compressed. Body moderately dorsoventrally compressed anteriorly, becoming increasingly laterally compressed posteriorly at region of dorsal and anal fins. Widest point of head wider than widest point of body (immediately behind head). Body width and depth tapering gradually posteriorly. Eye large, positioned on dorsolateral surface of head; orbit visible in ventral view. Centre of eye closer to tip of snout than to posterior margin of operculum. Snout short, broad, anterior margin rounded. Anterior nostril a small tubular opening, with short, thin blade-like flap extending from posterior margin. Posterior nostril tubular, situated along anterdorsal margin of orbit. Gill membranes united and free from isthmus. Mouth terminal, large; posterior tip of upper jaw reaching imaginary vertical line through centre of orbit when mouth closed. Upper lip fleshy, narrowest at centre; separated from snout by shallow groove. Lower lip fleshy, narrowest at centre, expanded into large lobes adjacent to lower jaw symphysis; lobes extend ventromedially to border anterior margin of mandibular rows of superficial neuromasts. Premaxilla with outer row of larger conical teeth with slightly recurved tips and medial patch of 20–30 smaller conical teeth on lingual surface adjacent to symphysis. Dentary with broad patch of conical teeth with slightly recurved tips anteriorly, tapering to single row of conical teeth posteriorly. Pharyngeal jaws comprising patch of 18–21 small conical teeth with slightly recurved tips on pharyngobranchial toothplate 3 and three rows of 6–11 small conical teeth with slightly recurved tips along ceratobranchial 5. 5–8 gill rakers located along anterior and posterior edge of ceratobranchials 2–3 and anterior edge of ceratobranchial 4; 1 gill raker located along anterior edge of ceratobranchial 1 (absent on either left or right side in two C&S specimens examined). Gill filaments associated with ceratobranchials 1–4 (3.5 gill filaments of Briggs, 1955); ceratobranchial 1–3 each with holobranch; hemibranch only on ceratobranchial 4. Basihyal spatulashaped; anterior edge tipped with cartilage. Branchiostegal rays 6; two anteriormost rays articulating medially with hyoid bar along anterior ceratohyal; posterior rays articulating with hyoid bar laterally, including 3 along anterior ceratohyal and 1 straddling junction between anterior and posterior ceratohyals.   FIGURE 2.  Trachelochismus aestuarium, NMNZ P.057566, holotype, 24.0 mm SL; New Zealand, Ngunguru River estuary at Ngunguru. Cephalic lateral-line system with 2 pores in nasal canal; 2 pores in postorbital canal; 3 pores in lachrymal canal; 3 pores in preopercular canal; 3 pores in mandibular canal. Second (LC2) and third (LC3) lachrymal canal pores flush with surface of skin or weakly elevated above skin surface. Suborbital, postorbital and mandibular rows of neuromasts located within shallow grooves; borders of grooves smooth, without paired-fleshy swellings adjacent to superficial neuromasts. 11–12 superficial neuromasts in suborbital row; 3 superficial neuromasts in postorbital row; 4–5 superficial neuromasts in mandibular row. Suborbital row extending along ventral margin of orbit; continuous. Dorsal-fin rays 7 or 8. Anal-fin rays 7 or 8. Principal caudal-fin rays 5 + 5, dorsal procurrent rays 8, ventral procurrent rays 8. Pectoral-fin rays 25. Pelvic-fin rays I.4.All fin rays unbranched and segmented. Caudal fin rounded, tips of principal caudal fin rays extended slightly beyond fin margin. Caudal-fin skeleton comprised of upper and lower hypural plates; epural and parhypural triangular and similar in size. Dorsal-fin origin situated slightly anterior to imaginary vertical line through anal-fin origin. First dorsal-fin pterygiophore inserted between neural spines of vertebrae 17/18. First anal-fin pterygiophore inserted between hemal spines of vertebrae 18/19 or 19/20. Total number of vertebrae 32, consisting of 14 abdominal and 18 caudal vertebrae. Ribs 11, associated with vertebrae 3–13. Epicentrals 20, associated with vertebrae 2–21.   FIGURE 3.Head (in dorsal, lateral and ventral view) of  Trachelochismus aestuarium, AIM MA6949, 29.2 mm SL, highlighting position of cephalic lateral line canal pores (grey circles) and superficial neuromasts (white circles) on the left side of the head. Superficial neuromasts arranged in rows are connected by a thin black line. Superficial neuromasts on surface of body not highlighted. Asterisks (*, **, ***, ****) label individual superficial neuromasts, not arranged in rows, which are visible in different views. Abbreviations: AN, anterior nostril; FN, superficial neuromast; LC1–3, lachrymal canal pores 1–3; LL, lower lip; MC1–3, mandibular canal pores 1–3; MR, mandibular row; NC1–2, nasal canal pores 1–2; O, orbit; PF, paired fold; PN, posterior nostril; PO1–2, postorbital canal pores 1–2; POG, postorbital row; PR1–3, preopercular canal pores 1–3; SOG, suborbital row.   FIGURE 4.Scanning electron micrographs of lachrymal pores, nostrils (A, C, E; lateral view), and mandibular row of superficial neuromasts (B, D, F; ventral view) in three species of  Trachelochismus. A, B.  T. aestuarium, TCwC 17266.03, paratype, 24.0 mm SL. C, D.  T. pinnulatus, TCwC 17269.06, 29.0 mm SL. E, F.  T. melobesia, TCwC 17174.01, 18.2 mm SL. Abbreviations: AN, anterior nostril; F, flap associated with anterior nostril; FN, superficial neuromast; LC1–3, lachrymal canal pores 1–3; LL, lower lip; MC1, mandibular canal pore 1; NC1–2, nasal canal pores 1–2; O, orbit; PF, paired fleshy fold; PN, posterior nostril; SOR, suborbital row; UL, upper lip. Adhesive disc large, double ( Fig. 5A); anterior margin smooth; posterior margin weakly crenulated. Disc region A without papillae at centre; lateral margins with 3–4 transverse rows of papillae. Apapillate region of disc region A equal in width or wider than region C. Disc region B with 4–5 transverse rows of papillae. Disc region C with 3–4 rows of papillae. Papillae of disc region A decreasing in diameter towards outer margin of disc. Papillae of disc region B and C decreasing in diameter towards outer margin of inner disc. Dorsal postcleithrum a small, thin bone, irregular in shape; articulating with dorsal face of ventral postcleithrum ( Fig. 5B). Ventral postcleithrum larger than dorsal postcleithrum; irregular in shape, wider laterally than medially, with convex anterior and posterior outlines ( Fig. 5B). Fimbrae along posteriorlateral margin of ventral postcleithrum well-developed. Ventral postcleithra articulating along ventral midline via a well-developed cap of dense connective tissue. Skin associated with last pelvic-fin ray attaching to base of pectoral fin opposite 4th lowermost pectoral-fin ray.  Colouration.In alcohol, head and body background colour pale yellow, without noticeable markings. In formalin and shortly after initial transfer to alcohol, body with irregular dark red to orange markings covering entire dorsal and lateral surface and ventral surface posterior to adhesive disc ( Fig. 2). Head with irregular dark red stripe on lateral surface extending from posterior margin of orbit to point just anterior to operculum; increasing in depth posteriorly. Fins hyaline. In life, background colour highly variable, ranging from pale pink to green ( Fig. 6). Entire dorsal and lateral surface of body and head, and ventral surface of body posterior to adhesive disc covered with light to dark brown erythrophores. Erythrophores responsible for myriad of irregular markings over dorsal and lateral surface of body, ranging from thin dark brown markings that coalesce to form a mottled pattern against lighter background colour, to broader dark brown saddle-like markings along dorsal midline that may or may not extend ventrad over lateral surface of body ( Fig. 6C). Dorsal, anal and caudal fins with irregular light to dark brown markings. Pectoral fin transparent. Dark brown to black streak passing through eye on lateral surface of head; increasing in depth posteriorly. Dorsal margin of streak solid; ventral margin irregular, edged in brilliant white ( Fig. 6C).   Distribution.  Trachelochismus aestuariumis known only from shallow (0–29 meters in depth) bay and estuarine areas along the coast of New Zealand( Fig. 7) usually in association with mixed shell-bryozoan rubble benthic communities. Several paratypeshave also been collected in association with Zostraand mangroves. At the typelocality in the Ngunguru River estuary at Ngunguru,  T. aestuariumis found predominantly in association with spent shells of bivalves over a substrate of fine sand and silt at depths below the low tide mark (0–3 meters in depth). Though  T. aestuariumhas been collected throughout coastal New Zealand, the majority of specimens have been collected from along the northeast coast of the North Island ( Northland, Auckland, Waikato, to the Bay of Plenty).   Etymology.From the Latin  aestuarium,a tidal inlet of the sea, reflecting the presence of this species in estuaries. A noun in apposition.   Comparisons.  Trachelochismus aestuariumdiffers most noticeably from  T. pinnulatusand  T. melobesiaby the shape of the flap associated with the anterior nostril, head profile, and live colouration. In  T. aestuariumthe flap associated with the posterior margin of the anterior nostril is thin and blade-like ( Fig. 4A) and does not reach the anterior margin of the orbit when pressed backwards against the head. In  T. melobesiathe flap is also blade-like but much longer ( Fig. 4E), reaching past the anterior margin of the orbit when pressed backwards. In  T. pinnulatus,the flap is short (i.e., not reaching the anterior margin of the orbit when pressed backwards) but scallop-shaped, with a broad, crenulated dorsal margin ( Fig. 4C). In  Trachelochismus aestuariumlachrymal canal pores 2 and 3 are flush with surface of skin, or only weakly elevated above the surface of the skin ( Fig. 4A). In  T. melobesiaand  T. pinnulatusthese pores are located at the end of short tubes that overlap the dorsal margin of the upper lip when the mouth is closed ( Fig. 4C, E). In life,  T. aestuariumexhibits a single dark brown to black streak posterior to the orbit with an irregular ventral margin that is bordered by white compared to multiple darkly coloured stripes alternating with thin white stripes radiating from the posteroventral margin of the orbit in  T. melobesiaand  T. pinnulatus.   FIGURE 8.Head (in dorsal, lateral and ventral view) of  Trachelochismus melobesia, TCwC 17264.05, 25.8 mm SL, highlighting position of cephalic lateral line canal pores (grey circles) and superficial neuromasts (white circles) on the left side of the head. Superficial neuromasts arranged in rows are connected by a thin black line. Superficial neuromasts on surface of body not highlighted. Asterisks (*, **, ***, ****) label individual superficial neuromasts, not arranged in rows, which are visible in different views. Abbreviations: AN, anterior nostril; FN, superficial neuromast; LC1–3, lachrymal canal pores 1–3; LL, lower lip; MC1–3, mandibular canal pores 1–3; MR, mandibular row; NC1–2, nasal canal pores 1–2; O, orbit; PF, paired fold; PN, posterior nostril; PO1–2, postorbital canal pores 1–2; POG, postorbital row; PR1–3, preopercular canal pores 1–3; SOG, suborbital row.   TABLE 2.Select morphometric characters for  Trachelochismus aestuarium(n = ƖO),  T. pinnulatus(n = 9) anđ  T. melobesia(n = ƖO)      Trachelochismus   aestuarium   Trachelochismus pinnulatus   Trachelochismus melobesia  Holotype Range Mean St. Dev. Range Mean St. Dev. Range Mean St. Dev.  Stanđarđ Length (SL) 24 2Ɩ.3̅38.9 – – 27.4̅7O.5 – – 24.8̅28.O - –   In % of SL  Heađ length (HL) 34.4 32.4̅37.8 34.8 Ɩ.8 4O.Ɩ̅44.8 4Ɩ.5 2 39.6̅44.2 42.5 Ɩ.5  Bođy đepth Ɩ5.3 Ɩ3.2̅Ɩ5.5 Ɩ4.8 O.8 Ɩ3.O̅Ɩ8.2 Ɩ4.8 Ɩ.8 Ɩ3.3̅Ɩ5.4 14.2 0.7  Pređorsal length 74.6 7Ɩ.O̅74.6 72.7 Ɩ.Ɩ 75.2̅8O.4 77.8 Ɩ.9 68.5̅73.5 7Ɩ.3 Ɩ.5  Preanal length 75.5 72.Ɩ̅77.9 74.5 2 75.8̅8Ɩ.8 79.7 2.Ɩ 73.O̅78.9 75.9 Ɩ.7  Preanus length 6Ɩ.4 58.2̅62.O 59.7 Ɩ.4 63.2̅7O.9 67.7 2.7 65.8̅69.8 68 Ɩ.3  Anus to đisc Ɩ4.7 Ɩ2.9̅Ɩ8.O Ɩ4.7 Ɩ.5 ƖƖ.7̅Ɩ6.7 Ɩ4.2 Ɩ.9 9.9̅Ɩ3.Ɩ ƖƖ.2 Ɩ.3  Anus to anal fin Ɩ2.5 ƖO.2̅Ɩ3.3 Ɩ2.2 Ɩ.Ɩ 9.5̅Ɩ2.6 ƖO.9 Ɩ.2 5.2̅8.7 6.5 Ɩ.3  Cauđal peđuncle length 9.5 7.3̅9.6 8.5 O.9 8.4̅ƖO.2 9 O.7 5.6̅9.3 7.2 Ɩ.Ɩ  Cauđal peđuncle đepth ƖƖ.2 ƖO.9̅Ɩ2.7 ƖƖ.6 O.6 9.7̅Ɩ2.8 ƖƖ O.9 9.Ɩ̅ƖO.9 9.9 O.5  Disc length 27.4 22.2̅27.8 26.Ɩ Ɩ.9 25.7̅29.8 28 Ɩ.7 23.9̅3O.7 27.7 2.Ɩ  Disc wiđth 25.6 22.5̅27.O 24.8 Ɩ.5 26.3̅28.7 27.9 O.8 24.Ɩ̅28.5 26.8 Ɩ.4   In % of HL  Heađ đepth at orbit 26.9 24.5̅34.9 27.4 3.4 25.6̅29.6 28 Ɩ.2 29.4̅32.8 3Ɩ.5 Ɩ.Ɩ  Heađ wiđth at orbit 53.8 46.5̅56.6 5Ɩ.2 2.9 53.6̅63.O 57.2 4.Ɩ 54.O̅6Ɩ.3 57.6 3.Ɩ  Heađ wiđth at wiđest point 72.3 65.7̅84.3 72.2 5.5 65.6̅82.7 75.2 5.4 79.8̅9Ɩ.O 86.2 3.7  Interorbital wiđth 36.Ɩ 3Ɩ.6̅37.8 34.6 2.6 23.6̅33.6 29.7 3.3 Ɩ8.Ɩ̅22.Ɩ 2O.3 Ɩ.3  Snout length 28.6 23.2̅28.6 25.8 Ɩ.8 26.O̅32.7 29.7 2.4 23.9̅3Ɩ.5 28 2.5  Eye điameter Ɩ8.5 Ɩ6.O̅24.6 Ɩ9.5 2.7 Ɩ2.9̅Ɩ9.8 Ɩ5.7 2.3 Ɩ7.2̅2Ɩ.6 Ɩ9.8 Ɩ.8   TABLE 3.Means of corrected distances within(*) and between three species of  Trachelochismusbased on COI sequence data (684bp).     Species   T. melobesia(n = 7)   T. pinnulatus(n = 3)   T. aestuarium(n = 3)    T. melobesia 0.3* - -    T. pinnulatus 13.5 0.2* -    T. aestuarium 12.9 4.8 0.2*   Trachelochismus aestuariumis further distinguished from  T. melobesiaby the absence (vs. presence) of papillae along the centre of disc region A (compare Fig. 5Avs. 5E), a greater interorbital width (31–38% HL vs. 18–22% HL), the presence (vs. absence) of gill rakers along the anterior edge of ceratobranchial 1, fewer dorsal-fin rays (8 vs. 11), a greater number of pectoral-fin rays (25 vs. 23) and caudal vertebrae (18 vs. 16), a greater number of superficial neuromasts in the mandibular (4–5 vs. 3) and postorbital rows (3 vs. 2), a continuous (vs. discontinuous) suborbital row of superficial neuromasts (compare Fig. 3vs. 8), and the absence (vs. presence) in life of a broad solid or broken pinkish marking that is edged with white and extends over most of the dorsal surface anterior to the origin of the dorsal fin (see Plate 7 B in Paulin & Roberts, 1992; Fig. 9herein).   Trachelochismus aestuariumis further distinguished from  T. pinnulatusby the absence (vs. presence) of paired-fleshy swelling associated with superficial neuromasts on the surface of the head and most obviously those located in the suborbital, mandibular and postorbital rows ( Fig. 1), by having the suborbital, mandibular and postorbital rows of superficial neuromasts contained within a shallow (vs. deep) groove (compare Fig. 4A,Bvs. 4C,D), fewer gill-rakers along the anterior margin of ceratobranchial 1 (1 vs. 3), and by the width of the apapillate area of adhesive disc region A (as wide or wider than region C vs. narrower; compare Fig. 5Avs. 5C).  Uncorrected pdistances for the 684 bp sequence of the COI gene analysed herein between  T. aestuariumand its congeners range from 4.8 (  T. pinnulatus) to 12.9 (  T. melobesia) ( Table 3).  Phylogenetic Relationships.The phylogenetic position of  Trachelochismus aestuariumdiffered between the topologies resulting from the analyses of the different gene data sets.  Trachelochismus aestuariumand  T. pinnulatusare sister groups in the topologies resulting from the analyses of the mitochondrial genes ( Fig. 9A), whereas  T. aestuariumis placed as the sister taxon to  T. melobesia+  T. pinnulatusin topologies resulting from the analyses of ZIC1 ( Fig. 9B). At least one morphological character, the absence of papillae at the centre of adhesive disc region A (a derived condition within Gobiesocidae; K.W. Conway, pers. obs.), provides evidence in support of the hypothesis that  T. aestuariumand  T. pinnulatusare sister species. Though a detailed investigation of the morphology of the three species of  Trachelochismushas yet to be conducted, we are aware of no apomorphic characters that would support the alternative hypothesis that  T. melobesiaand  T. pinnulatusare sister groups. 5891817314 2016-03-09 NMNZ I. Middleton & K. W. Conway & S. Hannam & G. Short & T. Trnski. New Zealand -35.629665 Ngunguru 11 174.50684 Ngunguru River 3 534 1 Northland holotype 5891817302 1931-05-04 AIM New Zealand -36.816666 Papakohatu (Crusoe) Island 1 174.96666 Waitemata Harbour 3 534 MA451, 2, 29.1 1 Auckland paratype 5891817327 1979-07-03 AIM New Zealand Whangateau Harbour -36.808334 Motuihe Island 19 174.92667 Emu Point 3 534 MA3082, 1, 37.4 1 Auckland paratype 5891817323 1982-06-20 AIM Whangateau Harbour New Zealand Omaha River 3 534 MA4968, 2, 26.8-27.8 1 Auckland paratype 5891817315 2011-10 AIM New Zealand -36.866665 Tamaki Estuary 1 174.90118 3 534 MA30483, 1, 39.1 1 Auckland paratype 5891817319 1930-03-28 AIM New Zealand Waitemata Harbour -36.77889 Motutapu 19 174.96333 Motuihe 3 534 MA80711, 2, 23.2-29.2 1 Auckland paratype 5891817312 1955-10 NMNZ New Zealand -36.433334 Fairchild Island 11 175.78334 3 534 1 Auckland paratype 5891817310 1979-01-21 87-01-21 1979-01-21 NMNZ, NZOI New Zealand -37.671665 Motiti Island 11 176.37833 3 534 BS738 1 Bay of Plenty paratype 5891817333 2002-04-16 NMNZ New Zealand Whangapoua Harbour -36.75 Zostra 11 175.63333 East Coromandel 3 534 1 Bay of Plenty paratype 5891817337 1990-02-27 NMNZ New Zealand -40.921665 D'Urville Island 11 173.77 Off Cone Island 3 534 1 Marlborough paratype 5891817311 1992-10-17 AIM New Zealand 1 Ngamungu Point 3 534 MA77653, 1, 22.7 1 Northland paratype 5891817304 1993-10-17 AIM New Zealand Parengarenga Harbour -34.525 Dog Island 19 172.94667 Te Pua Point 3 534 MA80328, 1, 21.3 1 Northland paratype 5891817309 [151,1104,151,176] 2015-02-14 TCWC I. Middleton & K. W. Conway & S. Hannam & G. Short & T. Trnski. New Zealand -35.629665 Ngunguru 11 174.50684 Ngunguru River 4 535 TCWC 17172.01, 2, 11.3-24.9 1 Northland paratype 5891817325 1956-08 NMNZ Zostra New Zealand -37.65 Tauranga Harbour 11 176.08333 4 535 1 Northland paratype 5891817330 1981-01-27 NMNZ, NZOI New Zealand -34.806667 Ranganui Bay 7 173.325 4 535 BS870 1 Northland paratype 5891817344 1981-02-03 NMNZ, NZOI New Zealand -34.416668 Spirits Bay 11 172.77667 4 535 BS916 1 Northland paratype 5891817331 1981-02-03 NMNZ, NZOI New Zealand -34.426666 Spirits Bay 9 172.80333 4 535 BS915 1 Northland paratype 5891817318 1981-01-27 NMNZ, NZOI New Zealand -34.826668 Ranganui Bay 11 173.25 4 535 BS871 1 Northland paratype 5891817301 1981-01-27 94-01-21 1981-01-27 NMNZ, NZOI New Zealand -34.806667 Ranganui Bay 11 173.325 4 535 BS870 1 Northland paratype 5891817316 1983-10-22 NMNZ New Zealand Hope Passage -35.216667 Rawhiti Point 11 174.25 Albert Channel 4 535 1 Northland paratype 5891817342 1981-01-27 NMNZ, NZOI New Zealand -34.826668 Off Ranganui Bay 11 173.25 4 535 BS871 1 Northland paratype 5891817324 NMNZ New Zealand -35.816666 Whangarei Heads 11 174.5 4 535 1 Northland paratype 5891817336 1997-04-03 NMNZ New Zealand -35.815 Darch Point 11 174.48 Whangarei Harbour 4 535 1 Northland paratype 5891817326 2015-02-02 NMNZ New Zealand -35.570168 Matapouri 11 174.5115 Estuary 4 535 1 Northland paratype 5891817322 2015-01-07 NMNZ New Zealand -35.633 Ngunguru River 11 174.50583 Sand 4 535 1 Northland paratype 5891817340 2001-02-21 NMNZ New Zealand -37.008667 Tairua Harbour 11 175.85283 4 535 1 Waikato paratype 5891817308 NMNZ New Zealand Wellington 4 535 1 Wellington paratype 5891817335 1971-03-18 VUW Stn. & V Tirohia, BS New Zealand 4 -41.25 Eastbourne 11 174.86667 Ward Island 4 535 1 Wellington paratype 5891817305 1970-11-04 NMNZ New Zealand Foveaux Strait -46.533333 Bluff 11 167.76666 Stewart Island 4 535 1 Wellington paratype 5891817317 1970-11-04 NMNZ New Zealand Foveaux Strait -46.533333 Bluff 11 167.76666 Stewart Island 4 535 1 Wellington paratype 5891817307 NMNZ New Zealand -40.2825 Eastbourne 11 174.9 Off Days Bay 4 535 1 Wellington paratype 5891817320 NMNZ, AIM New Zealand -41.1 South Island 11 174.9 4 535 MA6949, 1, 29.2 1 Otago paratype 5891817334 [259,1402,1087,1112] 1988-01-06 New Zealand -45.833332 Portobello Bay 1 170.665 4 535 1 Otago paratype 5891817343 [151,1402,1124,1149] 1962-08-13 NMNZ New Zealand -45.833332 Portobello 11 170.65 4 535 1 Otago paratype 5891817345 02-01-23 1952-11-09 02-01-23 NMNZ New Zealand -45.833332 Portobello 11 170.65 4 535 1 Otago paratype 5891817341 2003-08-05 NMNZ, NIWA Stn. New Zealand 1 -45.823 Portobello Bay 11 170.66234 4 535 SVDUD2287 1 Otago paratype 5891817338 1971-03-10 NMNZ FM Climo New Zealand 8 -40.516666 Puponga 11 172.73334 4 535 1 Tasman paratype