Corresponding author: Richard L. Pyle (
Academic editor: Lyubomir Penev
In their revision of the triggerfish genus
Deep dives were made using Cis-Lunar Mk-5P mixed-gas, closed-circuit rebreathers. Specimens were collected by hand and by hand net.
Counts and measurements follow the methods described by
Standard length
Maximum depth measurement may be variable due to the degree of extension of the pelvic flap when the individual specimen was preserved. Width of the body is the maximum width. Depth of the caudal peduncle is the least depth. Eye diameter is the maximum fleshy diameter. Interorbital width is the least bony width. Interdorsal space is the distance from the posterior edge of the first dorsal spine at its base to the origin of the first ray of the second dorsal fin (excluding the basal scaly sheath). Measurement of the longest ray of the second dorsal and anal fins exclude the basal scaly sheath. Bases of the second dorsal and anal fins were measured from the anterior margin of the first ray at the upper end of the basal scaly sheath to the posterior edge of the last ray. Caudal concavity is the horizontal distance between the distal tips of the longest and shortest caudal rays.
Tissue samples intended for DNA sequencing were removed from collected specimens prior to formalin fixation in the field, but these tissue samples were subsequently lost in transit. Description of this species was postponed for eight years in anticipation of obtaining additional specimens from Kiritimati or other nearby localities, but following exploration of similar habitats in French Polynesia, the Cook Islands, and Johnston Atoll without observing this species, we have elected to describe this new species without molecular analysis.
The holotype has been deposited at the Bernice Pauahi Bishop Museum fish collection, Honolulu (BPBM); and paratypes have been deposited at BPBM, the California Academy of Sciences fish collection, San Francisco U.S. National Museum of Natural History, Washington, D.C.
Proportional measurements expressed as a percentage of standard length (SL). Data in parentheses apply to paratypes, when different from the holotype (see also Table
Dorsal soft rays 29; anal rays 25; pectoral rays 13 (rarely 14); body scale rows 34 (33-35); head scale rows 18 (17-18); vertebrae 18, gill rakers 36 (holotype only).
Greatest depth of body 49 (45-50), depth at origin of anal fin 41 (42-43), width of body 29 (19-20), head length 32 (31-33), snout length 21 (20-21), snout to origin of first dorsal fin 33 (32-35), snout to origin of anal fin 69 (67-69), base of second dorsal fin 36 (35-37), base of anal fin 30 (30-32).
Eye diameter 6.5 (7.2-8.8), interorbital width 12 (12-13), length of gill opening 10 (9-10), depth of caudal peduncle 8.4 (8.4-9.0), length of first dorsal spine 14 (13-17), length of longest dorsal soft ray 19 (19-22), length of longest anal ray 18 (16-19), interdorsal space 25 (23-25), length of caudal fin 26 (21-26), caudal concavity 4.5 (2.1-5.8), length of pectoral fin 11 (12-14).
Dorsal and ventral profiles of head strongly convex; three longitudinal slightly diagonal darkly pigmented grooves on head following border of scale rows, running from behind and below corner of mouth, converging slightly as they pass posteriorly, and nearly reaching gill opening and upper pectoral base; a groove running anteriorly and diagonally downward from front of eye, extending approximately half the distance to tip of snout; deep medial groove behind first dorsal fin extending approximately half distance from last spine to origin second dorsal; pelvic flap not developed, pelvic terminus barely movable, small, slightly over one half orbit diameter.
Color in life as in Figs
Color in alcohol tan, paler ventrally; pale brown spots dorsally from origin of dorsal fin to caudal peduncle, more spots anteriorly; grooves in cheek brown; opercular membrane brown, faint brown bar posterior to gill opening from mid-orbit to mid pectoral base; brown line below lower lip extending diffusely beyond corner of mouth; anterior nostril in a small white spot; first dorsal spine light brown, darker distally on some specimens, membrane of first dorsal fin brown, darker posteriorly; second dorsal and anal fins pale with light brown rays; caudal fin pale yellow; pectoral fins translucent.
Dorsal rays III, 29; anal rays 25; pectoral rays 13–14 (usually 13); body scale rows 33-35; head scale rows 17–18; gill rakers 36; body depth 2–2.22 in SL; color in life pearly gray with honey-brown spots sub-dorsally on body in several irregular rows between the first dorsal spine and the caudal peduncle; opercular membrane darkly pigmented with three cheek grooves pigmented pale blue; first dorsal fin light tan brown becoming dark distally, first dorsal fin membrane basally tan, dark brown distally, second dorsal and anal fins with light brown rays, light blueish membranes; caudal fin with reddish upper and lower margins, a broad reddish crescent posteriorly in fin not extending to upper and lower margins.
Named for Brian D. Greene, a member of the deep diving team that discovered species, in recognition of his efforts to collect the type specimens.
Relatively abundant within its depth range and habitat (coral rubble and holes adjacent to deeper drop-offs, below a thermocline) at several localities on the west and north coasts of Kiritimati (Christmas Island). Always observed near the reef substratum, where it would retreat to shelter when approached.
Currently known only from Kiritimati (Christmas Island) in the Line Islands. Further exploration of mesophotic coral ecosystems in the tropical Pacific may extend the known range of this species, although it was not observed during exploratory dives within the mesophotic depth range in the Hawaiian Islands, Johnston Atoll, Caroline Islands, Cook Islands, French Polynesia, or elsewhere in the Pacific.
1 | Cheek with three prominent slightly diagonal dark brown or blue grooves (a shorter narrower groove above and below the main three sometimes dark on |
2 |
– | Cheek with five or six grooves (darkly pigmentd only on |
4 |
2 | Lines or spots on body scales; scale rows between upper end of gill opening and caudal base 39-50 | 3 |
– | Lines or spots on body restricted to row of brown spots dorsally; scale rows between upper end of gill opening and caudal base 33-35 (Line Islands) | |
3 | Body with a single round to longitudinally elliptical dark brown spot at corner of each scale; scales between upper end of gill opening and caudal fin base 39 to 44 (tropical Atlantic) | |
– | Upper half of body with longitudinal dark brown lines following scale rows, lower half with a dark brown dash or spot at corner of each scale; scales between upper end of gill opening and caudal fin base 44 to 50 (Indian Ocean, Australia, and Japan) | |
4 | Depth of body at anal fin origin 2.45 to 2.68 in standard length; scales of body with a prominent median elevation, forming longitudinal ridges (better developed posteriorly) (Indo-Pacific) | |
– | Depth of body at anal fin origin 2.7 to 3.43 in standard length; scales of body with only slight median ridges posteriorily on body | 5 |
5 | Dorsal soft rays 29 to 32; anal soft rays 26 to 29; no longitudinal blue line on body (eastern, central and western Pacific) | |
– | Dorsal soft rays 26 to 28; anal soft rays 23 to 25; an irregular longitudinal blue line on body from pectoral axil to upper side of caudal peduncle (Indo-Pacific) |
Based on the key included in
Table
While
We are indebted to Brian D. Greene for his contributions to work and for collecting the type specimens of this species. We also wish to thank General Electric (GE) and the Association for Marine Exploration (AME), which supported the expedition on which this new species was first discovered. Arnold Y. Suzumoto provided curatorial assistance, and Loreen O'Hara created radiographs of the type specimens.
Holotype of
Paratypes of
Proportional measurements and counts of type specimens of
Holotype | Paratypes | |||||
---|---|---|---|---|---|---|
BPBM 40262 | BPBM 40228 | BPBM 40342 | BPBM 40342 | USNM (pending) | CAS 236257 | |
Standard Length (SL) | 154 mm | 139 mm | 144 mm | 97 mm | 113 mm | 109 mm |
Greatest depth of body | 49 | 45 | 49 | 49 | 47 | 50 |
Depth of body at A origin | 41 | 43 | 42 | 42 | 42 | 42 |
Width of body | 20 | 20 | 20 | 20 | 19 | 19 |
Head length | 32 | 32 | 31 | 33 | 31 | 31 |
Snout length | 21 | 21 | 21 | 21 | 20 | 20 |
Snout to first dorsal fin | 33 | 32 | 33 | 35 | 33 | 33 |
Snout to anal fin | 69 | 67 | 68 | 69 | 67 | 68 |
Base of second dorsal fin | 36 | 37 | 37 | 35 | 36 | 36 |
Base of anal fin | 30 | 32 | 31 | 30 | 31 | 31 |
Eye diameter | 6.5 | 7.2 | 7.3 | 8.8 | 8.4 | 8.7 |
Interorbital width | 12 | 12 | 13 | 13 | 12 | 12 |
Length of gill opening | 10 | 10 | 10 | 9 | 10 | 10 |
Depth of caudal peduncle | 8.4 | 8.6 | 9.0 | 8.8 | 8.4 | 8.7 |
Length of first dorsal spine | 14 | 13 | 17 | 16 | 16 | 16 |
Length of longest dorsal ray | 19 | 22 | 19 | 21 | 19 | 20 |
Length of longest anal ray | 18 | 19 | 17 | 19 | 16 | 19 |
Interdorsal space | 25 | 24 | 25 | 23 | 25 | 24 |
Length of caudal fin | 26 | 26 | 24 | 21 | 23 | 24 |
Caudal concavity | 4.5 | 5.8 | 5.6 | 2.1 | 4.4 | 3.7 |
Length of pectoral fin | 11 | 13 | 13 | 12 | 14 | 12 |
Dorsal-fin spines | 3 | 3 | 3 | 3 | 3 | 3 |
Dorsal-fin rays | 29 | 29 | 29 | 29 | 29 | 29 |
Anal-fin rays | 25 | 25 | 25 | 25 | 25 | 25 |
Pectoral-fin rays | 13 | 13 | 14 (13) | 13 | 13 | 13 |
Body scale rows | 34 | 35 | 35 | 34 | 34 | 33 |
Head scale rows | 18 | 17 | 17 | 18 | 17 | 18 |
Cheek grooves | 3+0 | 3+1 | 3+1 | 3+0 | 3+1 | 3+0 |
Vertebrae | 18 | 18 | 18 | 18 | 18 | 18 |
Comparison of diagnostic characters for
Species | Geographic Range | Pigmented Cheek Grooves | Maximum Size | Body Scale Rows |
---|---|---|---|---|
Kiritimati | 3 | 154 mm | 33-35 | |
Western Atlantic | 3 | 250 mm | 39-44 | |
W. Indian Ocean; Okinawa | 3 | 260 mm | 44-50 | |
Antitropical Pacific; Tropical E. Pacific | 5 | 300 mm | 41-50 | |
W. Indian Ocean to Hawaii | 5 | 227 mm | 42-47 | |
W. Indian Ocean to Hawaii | 5-6 | 420 mm | 40-48 |