Pempheris ypsilychnus, Mooi & Jubb, 1996

Mooi, R. D. & Jubb, R. N., 1996, Descriptions of two new species of the genus Pempheris (Pisces: Pempherididae) from Australia, with a provisional key to Australian species, Records of the Australian Museum 48 (2), pp. 117-130 : 123-127

Pempheris ypsilychnus n.sp.

Figs 4b, 6 -8; Tables 2-3

Pempheris analis (non Waite, 1910).- Tominaga, 1963: 276, 278, tab. 4 (description of posterior light organ, meristics, distribution).- Tominaga, 1968: 72, 74 -78, 80, 82, 86, tabs. 3-5 (descriptions of osteology, meristics, posterior light organ, and possible affinities).

Pempheris klunzingeri (non McCulloch, 1911).- Haneda et al., 1966: 537, figs. 3,4 (description of light organ structure, drawings of anatomy).

Pempheris sp. l.- Hutchins, 1994: 49 (Western Australian distribution).

Material examined. HOLOTYPE: WAM P.28059-019, 74.1 mm, Western Australia, Broome (17°59'S 122°11'E), 1 m, N.L. Sarti, 28 March 1982.

PARATYPES: 18 specimens, 51.5-117.7 mm. AMS I.l5557- 187, 7: 51.5-80.0 mm, Queensland, Gulf of Carpentaria (17°24'S 140009'E), 10 m, CSIRO Prawn Survey, 27 November 1963; CSIRO C 3443, 117.7 mm, Queensland, Gulf of Carpentaria (16°56.7'S 140008.8'E), 18 m, Rama stn 147, 11 September 1963; MPM 31024, 4 : 60.9- 78.9 mm, from AMS 1.15557 --187 ; NTM S. 13277-001, 88.5 mm, Queensland, east of Cape York Peninsula (11°21.4'S 142°58.2'E), 22 m , R. Williams , 1 December 1991 ; SMNS 14293 , 2 : 58.0- 68.3 mm, Western Australia, Exmouth Gulf, 6-12 km south of Exmouth (22°00'00"S 114°08'30"E to 22°02'20"S 114°08'30"E), 11 -14 m, R. Fricke and FlY "Denison", 2-3 September 1992 ; USNM 337546 , 63.7 mm, from MPM 31024; WAM P.28059-023, 66.7 mm, collected with holotype ; WAM P.28416-019, 91.2 mm, Western Australia, Gantheaume Pt. (17°58'S 122°IO'E), 2-5 m, N. Sarti and A. Williams, 13 September 1982 .

Other material: 44 specimens, 56.5-120.6 mm. AMS IA.1780- 81, 2: 91.5-92.4 mm, Queensland, Port Denison (20003'S 148°15'E), E.H. Rainford, 1924 ; AMS IB.7208, 65.0 mm, Queensland, Gulf of Carpentaria ; AMS 1.20769 - 045 , 110.1 mm, Cape York, Halfway Island , NNW face (11°23'S 142°57'E), 4 -9 m , AMS Australian Institute of Marine Science , 18 February 1979 ; AMS 1.15482 - 005 , 64.3 mm, Queensland, Heron Island (23°27'S 151°57'E), H. Choat, 16 June 1965 ; AMS 1.15557 - 289 , 8 : 56.5- 67.8 mm, Queensland, Gulf of Carpentaria (17°24'S 140009'E), 10 m , CSIRO Prawn Survey , 27 November 1963 ; CSIRO C2640 , 99.6 mm, Western Australia, Dampier Archipelago (20035'S 116°35'E), Vessel Lancelin, 1954 ; CSIRO C2786 , 95.2 mm, Western Australia, Exmouth Gulf ? (22°S 114°20'E), Vessel Lancelin ; CSIRO C2787 , 98.2 mm, as CSIRO C2786 ; CSIRO A 3230, 110.7 mm, Queensland, Gulf of Carpentaria , SE of Mornington Island (16°42.2'S 139°29.5'E), 12.6 m, Rama stn 336, 11 November 1963 ; CSIRO A3231 , 77.6 mm, as CSIRO A3230 ; CSIRO A3232 , 72.5 mm, as CSIRO A3230 ; NTM S.13236-001, 84.0 mm, Northern Territory, south of Sphinx Head, Marchinbar Island (11°16'S 136°41'E), 18 -21 m, H. Larson, 16 November 1990 ; WAM P.4317, 2: 77.3- 81.5 mm, Western Australia, Dampier Archipelago (20033'S 116°32'E), P. Barrett-Lennard, December 1957 ; WAM P.4687, 67.4 mm, Western Australia, Exmouth Gulf (22°05'S 114°15'E), 13 m (7 fthms) , R. McKay , 13 September 1958 ; WAM P.13415, 72.8 mm, Western Australia, Dampier Archipelago (20033'S 116°32'E), 1954 ; WAM P.13416-13421, 6: 113.8-120.6 mm, Western Australia, Shark Bay (25°21'S 113°44'E), F. Barrett-Lennard, September 1960 ; WAM P.13422, 68.2 mm, Western Australia, Exmouth Gulf (22°05'S 114°15'E) , R.J. McKay , 13 September 1958 ; WAM P.13458, 58.9 mm, Western Australia, Exmouth Gulf (22°05'S 114°15'E) , R. McKay , 1958 ; WAM P. 22950, 103.8 mm, Western Australia, Kendrew Island, Museum Bay (20029'S 116°32'E), B. Hutchins, 19 February 1973 ; WAM P.23659- 001, 95.4 mm, Western Australia, Carnarvon (24°53'S 113°40'E), 24 m (dredging at 13 fthms), D. Heald, 19 July 1972 ; WAM P.25113-001, 95.3 mm, WesternAustralia, Dampier Archipelago, Kendrew Island (20028'S 116°32'E), G . R. Alien , 6 November 1974 ; WAM P.25369-024, 6: 58.8- 80.8 mm, Western Australia, North West Cape, Outer Reef, off Tantabiddy Ck. (2P55'S 113°57'E), 8- lO m, G . R. AUen, 27 June 1975 ; WAM P.25508-017, 85.7 mm, Western Australia, Exmouth Gulf (21°57'S 114°12'E), B. Hutchins, 6-7 December 1975 ; WAM P.25508-051, 70.2 mm, Western Australia, Exmouth Gulf, 4 km from Exmouth (21°57'S 114°12'E), B. Hutchins, 6-7 December 1975 ; WAM P.26043- 001, 92.7 mm, Western Australia, Shark Bay (25°25'S 113°25'E), P. Barrett-Lennard, 1960 .

Diagnosis. Pempheris ypsilychnus is distinguished from all other members of the Pempherididae by the following combination of characters: all scales ctenoid and adherent; pelvic axillary scale present; lateral-line scales 62-74 (usually 63-69); gill raker counts on first arch 6-8 + 19-22 = 25-30 (usually 26-27); dark, Yshaped light organ visible through body wall between pelvic- and anal-fin origins, with its bifurcation around anus (Fig. 8).

Description. Dorsal-fin rays VI,lO (VI,lO; V-VI,9-11, V only once, rarely 11); anal-fin rays III,33 (III,34; Ill,30-36, once 30); pectoral-fin rays 17 (17; 16-18); pelvic-fin rays 1,5; principal caudal-fin rays 9+8; upper procurrent rays 6,2 (6,2; 5-8,1-2); lower procurrent rays 3,2 (3,2; 3-5,1-2); lateral-line scales 64 (68; 62-74, rarely more than 70); scale rows above lateral line 9 (10; 9-11); scale rows below lateral line 18 (18; 17- 21); cheek scale rows 7 (6-9, extremes less common); predorsal scales 39 (39; 35-45, usually 37-43); circumpeduncular scales 22 (24; 22-26, usually 23-24); gill rakers 6+21 (7+20; 6-8, rarely 8 + 19-22); total gill rakers 27 (27; 25-30, most frequently 26-27, once 30).

As percentage of SL: head length 35.2 (34.5; 31.8- 39.4); head depth 33.7 (34.0; 30.0-39.7); snout length 7.7 (7.0; 5.8-8.l); eye diameter 14.8 (15.1; 13.2-16.5); interorbital width 8.9 (8.0; 6.5 -9.3); upper jaw length 19.0 (19.0; 17.3-20.5); predorsal length 41.0 (40.0; 36.1-44.7); prepelvic length 38.1 (38.7; 33.8-49.3); preanal length 57.8 (59.9; 54.0-66.1); pelvic-fin origin to anal-fin origin 22.5 (24.5; 19.8-29.6); body depth 43.8 (41.9; 37.1-46.0); pectoral-fin length 28.2 (27.9; 24.1 -31.7); pelvic-fin length 19.2 (19.6; 17.4-21.8); dorsal-fin base 20.6 (20.3; 18.1-23.0); longest dorsalfin ray 24.8 (24.3; 20.7-26.8); anal-fin base 43.1 (43.2; 40.5-46.0); longest anal-fin ray 19.8 (18.7; 15.0 -21.7); caudal-peduncle length 12.0 (10.7; 9.0-13.0); caudalpeduncle depth 10.8 (10.5; 9.2 -11.3); dorsal-fin origin to pelvic-fin origin 42.8 (41.5; 36.3-44.9); dorsal-fin origin to anal-fin origin 45.9 (45.3; 39.6-51.1); dorsalfin origin to anal-fin insertion 57.9 (57.2; 43.9-60.9).

Caudal fin forked. All scales ctenoid and adherent. Gular scaled. Pelvic axillary scale present. Prepelvic area (breast) unkeeled, flat and broad.

Anterior and posterior light organs V-shaped (Fig. 4b, 8). Anterior organ communicates with pyloric caeca, forward extension consisting of two ducts that unite anteriorly. Anterior organ underlain by pigmented tissue and layer of translucent muscle. Posterior organ communicates directly with the rectum ( Haneda et al., 1966: 537), underlain by a layer of pigmented tissue.

Coloration. Live colour unknown. Holotype preserved in 70% ethanol ( Fig. 7 ): dorsal part ofhead, nape, and body yellowish or straw and speckled with tiny dark brown chromatophores; cheek and particularly opercular area darker; preventral area anterior to pelvic-fin bases pale yellow and without chromatophores; dentaries without chromatophores, permitting dark bar on gular to show through; lower part of cheek dark; dark, Yshaped light organ visible through body wall between pelvic- and anal-fin origins, with wide bifurcation around the anus, silvery margins along length of linear portion; iris black; lateral-line scales without chromatophores making lateral line obvious on lightly speckled body; dorsal fin hyaline, with, at most, distal 1/4 of spines and first three segmented rays dark; anal fin hyaline, with distal 1/4 of first two segmented rays dark; pectoral and pelvic fins hyaline; medial caudalfin rays hyaline and speckled with tiny chromatophores, with bases yellow, three outermost branched rays and adjacent unbranched rays with black tips that gradually fade proximally. Colours of other preserved specimens very similar, differing in the following: variation in amount of black on tips of fins from none to 1/3 their length; occasionally silvery flanks; sometimes few or no chromatophores speckling body, sometimes more chromatophores, especially on ventral part of head; Yshaped light organ often with silver margins over entire length; iris sometimes coppery.

Comparisons. In Australia, this species is most likely to be confused with P. analis , P. compressa , and P. klunzingeri . Among these ctenoid-scaled Pempheris species, only P. ypsilychnus bears a pelvic axillary scale and has a Y-shaped posterior light organ visible through the body wall (Fig. 8). It is the only member of the genus with a Y-shaped anterior light organ (Fig. 4b). Total gill raker counts for P. ypsilychnus are considerably lower than other ctenoid-scaled members of the genus (25- 30 vs. 31-38). P. klunzingeri has the most similar body shape, but has five dorsal spines (vs. six) and a longer anal fin (anal-fin base:SL ratio 0.47-0.55, mean 0.51 vs. 0.41-0.46, mean 0.43) due to a higher number of segmented anal-fin rays (35-41 vs. 30-36); it also tends to have higher lateral-line scale counts (66-80, usually>70 vs. 62-74, usually 63-69) and the anterior light organ is restricted to a mop-like mass of tissue communicating with the pyloric caeca (Fig. 4c). P. analis tends to be deeper bodied (dorsal origin to pelvic origin:SL ratio 0.41 -0.46, mean 0.44 vs. 0.36-0.45, mean 0.42) with a longer anal-fin base (anal-fin base:SL ratio 0.43-0.49, mean 0.46 vs. 0.41-0.46, mean 0.43); additionally, it has no anterior light organ. P. compressa generally has higher numbers of segmented anal-fin rays (34-40 vs. 30-36) and, hence, a longer anal-fin base (anal-fin base:SL ratio 0.52-0.58, mean 0.54 vs. 0.41- 0.46, mean 0.43); it has no anterior light organ.

Distribution. Specimens have been collected at a number of sites in northern Australia, from the central west coast of Western Australia to the southern Great Barrier Reef ( Fig. 6 ). The southernmost record on the east coast, Moreton Bay near Brisbane, was reported by Haneda et al. (1966: 537) as Pempheris klunzingeri (a misidentification).

Biology. Little is known about this species. The largest known maximum size is 120.6 mm SL, and capture depths range from 1 m to 24 m. Haneda et al. (1966: 537) studied specimens obtained in a shrimp trawl, and described the anterior light organ as V-shaped, apparently overlooking the anterior portion of this structure (Fig. 4b). Body depth (measured as dorsal-fin origin to pelvicfin origin) varies geographically. Specimens from western localities (Shark Bay to Broome) have deeper bodies than those from eastern localities (Gulf of Carpentaria to Port Denison) (0.40-0.45, mean 0.43 vs. 0.36-0.42, mean 0.40; means significantly different, T=6.79, DF=60, p<O.OOl). Eastern specimens tend to have higher lateralline scale counts and more segmented anal-fin rays than western specimens (Tables 2, 3); the higher anal-fin ray counts are particularly noticeable among Gulf of Carpentaria examples ( Table 3 ).

Etymology. The specific name is a combination of ypsilon, the Greek letter Y, and lychnos, Greek for lamp or light. This combination alludes to the Y-shaped posterior organ that is visible through the body wall and characteristic of this species, reported to be luminescent ( Haneda et al., 1966). The epithet is to be treated as a noun in apposition.

Discussion. The relationships of these two new species cannot be determined at present. Preliminary results from a systematic revision of the family Pempherididae by the senior author, as well as the character distributions described by Tominaga (1968) and Jubb (1977), provide reason to doubt the monophyly of the two included genera, Parapriacanthus and Pempheris . The two new species exhibit the external features that traditionally have been used to characterise Pempheris (deep body, anal fin in scaly sheath, lateral-line scales extending to posterior margin of caudal fin), but share a number of internal features with the members of Parapriacanthus (cleithrum morphology, Y-shaped anterior light organ in Pempheris ypsilychnus ). Their placement in Pempheris should, therefore, be regarded as provisional.

Below is a key to the Australian species ofPempheris. In Australian waters, Pempheris can be distinguished from Parapriacanthus by: anal fin in scaled sheath (vs. no scaly sheath), 27 or more segmented anal-fin rays (vs. 27 or fewer), lateral-line extending to distal tips of medial caudal-fin rays (vs. to middle of medial caudal-fin rays), deeper body (head length about equal to body depth vs. head length generally greater than body depth). The key is provisional in two respects. First, the membership of Pempheris , as noted, is subject to change until the genus can be diagnosed by synapomorphies. Second, the identification of species of cycloid-scaled Pempheris , excepting perhaps P schwenkii , is questionable pending completion of a worldwide revision. Colour patterns noted below are those of adults. Distributions are taken from examined specimens and records in Hutchins (1994) and Hutchins & Swainston (1986). The authorship of P compressa to White (1790) follows the recommendation ofPaxton et al. (1989: 12).

Figures

Fig. 7. Holotype of Pempheris ypsilychnus n.sp., WAM P28059-019, 74.1 mm SL, Broome, Western Australia, preserved in ethanol. Scale bar is 10 mm.

Fig. 6. Distributions of the two new species of Pempheris. Arrows indicate ho1otype localities.

Tables

Table 3. Number of segmented anal-fin rays of specimens of Pempheris ypsilychnus n.sp. from western (Shark Bay to Broome) and eastern (Gulf of Carpentaria, Cape York and Great Barrier Reef) localities.

No. ofanal-finrays	30	31	32	33	34	35	36
Western localities		3	7	10	7	3
Cape York, GBR		2	2
GulfofCarpentaria	TODO		TODO	TODO	8	10	4