Nomorhamphus rex, Huylebrouck & Hadiaty & Herder, 2012

Huylebrouck, Jan, Hadiaty, Renny Kurnia & Herder, Fabian, 2012, Nomorhamphus Rex, A New Species Of Viviparous Halfbeak (Atherinomorpha: Beloniformes: Zenarchopteridae) Endemic To Sulawesi Selatan, Indonesia, Raffles Bulletin of Zoology 60 (2), pp. 477-485 : 479-484

Nomorhamphus rex , new species

( Figs. 2–8 ; Table 1)

Material examined. — Holotype – MZB 20724 (44.4 mm SL), male, Indonesia, Sulawesi, South Sulawesi Province, Wewu River which is a headwater of the Cerekang River drainage west of Lake Matano , sampling was conducted in a tributary at Village Laroeha , a small river few hundred meters upstream of the main river, 2°28.226'S, 121°04.125'E, F. Herder & R. K. Hadiaty, 4 May 2004.

Paratypes – ZFMK 44944–44955 , 5 males (28.9–41.5 mm SL), 7 females (34.5–63.9 mm SL), all collected with the holotype ; MZB 20725 and 20727–20730, 2 males (28.7–31.2 mm SL), 3 females (34.1–45.2 mm SL), all collected with the holotype ; ZSM 41743a–d, 2 males (29.2–31.1 mm SL), 2 females (41.5–45.3 mm SL), all collected with the holotype ; ZFMK 44956–44961 , 2 males (35.7–36.8 mm SL), 4 females (30.4–60.2 mm SL), Indonesia, Sulawesi, South Sulawesi Province, Toletole River at the village of Toletole, at a truck washing place about 150 m upstream of a large river bridge at the road to Wasaponda , 2°31.664'S, 121°06.726'E, F. Herder & R. K. Hadiaty , 4 May 2004 .

Additional non-type material – ZFMK 44962–44967 , 2 males (38.0– 42.5 mm SL), 4 females (55.1–62.5 mm SL), Indonesia, western central Sulawesi, Sulawesi Selatan, Tana Toraja, in a clearwater pool at an excavation of a small river with unknown name near the village of Tilanga , 3°02.126'S, 119°53.232'E, H.-G. Evers, J. Christian, P. Debold , T. Heinrich , 24 Sep.2010 ; ZFMK 44968–44979 , 2 males (both 31.5 mm SL, of which 1 male has been cleared and counterstained), 3 immature males (24.4–26.7 mm SL), 2 females (27.9–35.4 mm SL), 2 immature females (23.7–24.1 mm SL), 3 undet. (17.2–20.4 mm SL), all collected with the holotype; ZFMK 44980–44982 , 3 undet. (17.1–22.6 mm SL), same data as ZFMK 44956–44961 .

Diagnosis. — Nomorhamphus rex is distinguished from all other Nomorhamphus by the shape of the andropodium in males: spiculus sickle-shaped, curved dorsally, its proximal and middle segments in contact with the distal tip of the third anal-fin ray; distal segments of spiculus curved ventrally, without contact to third anal-fin ray; second anal-fin ray in males with three or four segments proximal to paired spines, third or fourth segment with a dorsal and a ventral row of “subsegments” forming squares and rectangles of different sizes, so that the third or fourth segment appears to be subdivided into two separate rays, from the half of its length up to the spines, with a varying number of subsegments (≥5 subsegments per row; see Fig. 2 ); first segment of the first anal-fin ray slightly constricted longitudinally, giving the appearance of two distinct rays; third anal-fin ray composed of two elongate segments, each approximately half the length of the entire ray, followed by a few short segments at the distal tip, which contact the spiculus; fourth anal-fin ray divided into three rows from approximately the third of its length, forming a kind of a covering for the third analfin ray with one dorsal and two lateral rows beneath. It is further distinguished from Nomorhamphus ebrardtii and N. kolonodalensis by having a relatively longer lower jaw (LJLB 5.7–11.3 times in SL vs. 13.4–15.9 in N. ebrardtii and 8.8–22.2 in N. kolonodalensis ; Meisner, 2001).

Description. — Morphometric and meristic characters are provided in Tables 1, 2. Body deep. Lower jaw relatively long, upper jaw longer than wide. Eye relatively large. Specimens> 35 mm SL with one row of conical teeth at the front of the upper and lower jaws, followed by two short rows of conical teeth, at the middle of the jaws three rows of conical teeth, followed again by two rows of conical teeth up to the end of the jaws; smaller specimens with one row of conical teeth at the front of the upper and lower jaws, followed by two rows of conical teeth up to the end of the jaws. Gill rakers tear-drop shaped, without teeth on the dorsal surface of the gill rakers. 45–51 [47] predorsal scales (76–83 predorsal scales in specimens from Tana Toraja, ZFMK 44962–44967). Fifth hypural fused to dorsal hypural plate. Caudal fin truncate, principal caudal-fin rays i,5–6/5–7,i (mode and holotype i,6/6,i), procurrent caudal-fin rays 5–6/5–6 (mode and holotype 5/6).

Life colouration. — Body yellowish brown to grey ( Fig. 3 ). Lips and beak red. Black pigment along ventral surface of lower jaw. Iris iridescent blue. Pelvic fins and anal fin yellowish hyaline. Black pigment on distal tips of anal-fin rays. A red spot between black distal tips and yellowish cryptoplica in males (in some males the red spot and/or the black pigment is absent or restricted to a few anal-fin rays). Pelvic fins with distal red band. Distinct black, oval spot anterior to pectoral fin; base of pectoral-fin rays light yellow, which merges into light red distally (pectoral fins transparent in some specimens). Dorsal fin red to orange with black pigment on distal tips of posterior dorsal-fin rays (black pigment absent in some males). Base of caudal fin yellowish hyaline, followed by a prominent red or orange part, distal band light dusky. Second half of thin midlateral stripe light reddish.

Preserved colouration. — Background colour brown ( Fig. 4 ) with thin midlateral stripe from pectoral to caudal fin, more prominent posteriorly. Distinct oval spot anterior to pectoral fin. Black pigment along ventral surface of lower jaw. Black pigment on distal tips of posterior dorsal-fin rays (absent in some males and smaller females) and on distal tips of anal-fin rays (absent in some males and smaller females). Smoky black mark on distal band of caudal fin. Specimens from Toraja with a slightly darker background colour.

Sexual dimorphism. — Females grow larger than males (maximum SL recorded: 44.4 mm in males, 63.9 mm in females). Males on average with a longer lower jaw (SL/LJLB 5.7–8.8 vs. 7.3–11.3 in females).

Distribution and habitat. — Nomorhamphus rex is known from two drainages leading to the same estuary at Bone

Bay, and one drainage leading to the Makassar Strait in Sulawesi Selatan, Indonesia ( Fig. 6 ). The holotype and part of the paratypes were taken from a tributary of Wewu River near the village of Laroeha, a headwater of the Cerekang drainage sharing the estuary region with the Malili Lakes (Larona River) drainage and several small rivers, including the Kawata River. The tributary of Wewu River locality (2°28.226'S, 121°04.125'E) is a small, fast-flowing river of few meters width partially covered by forest canopy, with a bed of gravel and sand. Other sympatric fish species recorded include Oryzias celebensis , Telmatherina cf. bonti , and the introduced Anabas testudineus , Channa striata , and Trichopodus pectoralis (Herder & Chapuis, 2010) . The second location is also in close vicinity of the Malili Lakes area: Toletole River at village Toletole, at a truck washing place about 150 m upstream of a bridge at the road to Wasaponda (2°31.664'S, 121°06.726'E). The Toletole River is a tributary of the comparatively small Kawata River, sharing the estuary with Rivers Cerekang and Larona (Malili Lakes drainage). The sample site is likewise a small, fast-flowing river with a bed of sand and gravel ( Fig. 7 ); other fish species recorded at this site include Mugilogobius sp. , and the introduced Channa striata , Clarias cf. batrachus , and Aplocheilus panchax . The third habitat is a natural clearwater pool, an excavation of a small stream with unknown name, located close by the village Tilanga in Tana Toraja. It is an approximately 4-m deep karst pond of 30–40 m length and up to 10 m width, used by local people as a natural “swimming pool”; other fish species occurring at this site include Oryzias sp. (Herder et al., in prep.) and the introduced Poecilia reticulata .

Etymology. — From the Latin rex , a king, in allusion to the teeth of the new species, reminiscent of the dentition of the late Cretaceous Tyrannosaurus rex . A noun in apposition.

Comparisons. — In contrast to other Nomorhamphus species from Sulawesi, N. rex is characterised by having a characteristic elongated and subdivided third or fourth segment in the second anal-fin ray in males ( Fig. 2 ). This clearly distinguishes N. rex from N. rossi and N. bakeri , in which the fifth or sixth segment is elongated, and from all remaining Nomorhamphus species described so far, having segments in this ray of approximately equal length (see Meisner, 2001). The new species is further distinguished from N. megarrhamphus and N. weberi by having a first anal-fin pterygiophore which is thickened and not angled anteriorly (see Meisner, 2001) and a less elongated lower jaw (lower jaw length following Brembach 5.7–11.3 times in SL in N. rex , vs. 4.0–5.7 times in SL in N. megarrhamphus and 3.7–4.9 times in SL in N. weberi ; Meisner, 2001). The new species is distinguished from N. brembachi , N. celebensis , N. kolonodalensis , N. liemi , and N. towoetii by its characteristic sickle-shaped spiculus ( Fig. 2 ). In N. brembachi and N. liemi the second anal-fin ray in males is curved at approximately ¼ its length so that the distal ½ slopes ventrally (see Meisner, 2001). In addition, N. brembachi , N. liemi , N. celebensis , and N. towoetii are characterised by lacking an elongate lower jaw and instead, have an upper and lower jaw approximately equal in length ( Meisner, 2001). Nomorhamphus rex is further distinguished from N. celebensis by its upper jaw width being less than upper jaw length (UJL/UJW 1.3–2.1 in N. rex vs. 0.70–0.94) and from N. towoetii by its yellowish brown to grey body colouration (vs. olive body with a large concentration of melanophores on lateral and dorsal body surfaces, which gives females a dusky appearance whereas large males are completely melanistic in N. towoetii ; Meisner, 2001).

Habitus and colouration of N. rex are most similar to N. kolonodalensis and N. ebrardtii . Among these species, N. rex is easily distinguished by features of the andropodium of males, including the sickle shaped spiculus, which contacts the distal segments of the third anal-fin ray with its proximal and middle segments, distal segments curved ventrally (vs. straight spiculus in N. kolonodalensis and elongated spiculus which is curved dorsally so that the expanded distal tip contacts the distal tip of the third anal-fin ray in N. ebrardtii ; Meisner & Louie, 2000) and the elongated third or fourth segment in third anal-fin ray (vs. segments approximately equal in length in N. ebrardtii and N. kolonodalensis ; Meisner, 2001). It is further distinguished by its longer lower jaw (LJLB 5.7–11.3 times in SL vs. 13.4–15.9 in N. ebrardtii and 8.8–22.2 in N. kolonodalensis ; Meisner & Louie, 2000; Meisner, 2001), the absence of teeth on the dorsal surface of gill rakers (vs. one to three teeth on the dorsal surface of some gill rakers on the second and third arches in N. kolonodalensis and N. ebrardtii ; Meisner, 2001, p. 251), the fifth hypural plate completely fused to dorsal hypural plate ( Fig. 8 ) (vs. fifth hypural partially seperate from dorsal hypural plate along most of its length in N. kolonodalensis ; Meisner & Louie, 2000), and black pigment on distal tips of posterior dorsal-fin rays and on distal tips of anal-fin rays (vs. no fin pigmentation in N. ebrardtii ; Brembach, 1991). Nomorhamphus rex occurs only west of Lake Matano and in Tana Toraja, Sulawesi Selatan, vs. Kabaena, Wowoni, Penango and Rumbia in Sulawesi Tenggara ( N. ebrardtii ), the Kolonodale region in Sulawesi Tengah and sites near Lake Towuti, Sulawesi Selatan ( N. kolonodalensis ) ( Popta, 1912; Brembach, 1991; Meisner & Louie, 2000, Meisner, 2001).

Remarks. — Following Meisner (2001), Nomorhamphus rex is clearly assigned to the genus Nomorhamphus (vs. Dermogenys , Hemirhamphodon , and Zenarchopterus ) by exhibiting the following combinations of characters: oval lacrimal; elongate, expanded autopalatine; teeth along the extended portion of the lower jaw absent; uniserial teeth not extending medially in a concave row from outer row of teeth; modified anal-fin rays in males with a fleshy covering (cryptoplica); second anal-fin ray in males without a distinct geniculus; melanophores anterior to the anal fin in females not forming a distinct spot. Specimens of N. rex from the Toraja population differ from those of the Rivers Wewu and Toletole in having more predorsal scales (45–51 [47] predorsal scales vs. 76–83 predorsal scales in specimens from Tana Toraja). Nevertheless, we consider all three populations conspecific based on andropodium structure and the lack of obvious differences in the other characters examined. We consider the disjunct distribution pattern of N. rex to represent an artifact of the incomplete sampling coverage in Sulawesi, highlighting the need for continued ichthyological surveys of the island’s freshwaters.

Comparative material. — Nomorhamphus ebrardtii Indonesia, Sulawesi Tenggara: Island of Wawoni ; D. Vogt Jul.1979: ZMH 7150 , 27 ex. (18 females, 39.1–60 mm SL, 9 males, of which two males are cleared and counterstained). – Nomorhamphus towoetii Indonesia, Sulawesi Selatan: Sungai Balambano, about 500 m above Balambano (road from Malili to Soroako); M. Kottelat & A. K. Kloetzli, 19 Jun.1988: MZB 5973 , 6 ex. (2 females, 39.3–49.4 mm SL, 3 males, 38.5–41.6 mm SL, 1 juv., 14,6 mm SL). – Nomorhamphus liemi Indonesia, Sulawesi Selatan: Highlands of Maros ; D. Vogt, Aug.1978: ZMH 7157 , 35 ex. (paratypes of Nomorhamphus liemi snijdersi (synonym of N. liemi ( Meisner, 2001) , 21 females, 14 males). – Nomorhamphus brembachi Indonesia, Sulawesi Selatan: Highlands of South Sulawesi, smaller mountain streams; D. Vogt, May1978: ZMH 7166 , 2 ex (paratypes, 1 female, 36.7 mm SL, 1 male, 38.8 mm SL). – Nomorhamphus brembachi Indonesia, Sulawesi Selatan: Highlands of Maros ; M. Brembach, Aug.1978: ZMH 7160 , 13 ex. (paratypes of Nomorhamphus ravnaki ravnaki , synonym of N. brembachi ( Meisner, 2001) , 5 females, 57–77.6 mm SL, 4 males, 34.2–39 mm SL, 4 undet.). – Nomorhamphus megarrhamphus Indonesia, Sulawesi Selatan: Lake Towuti, inlet of River Tominanga; F. Herder & A. Nolte, 28 Nov.2002: ZFMK 44923 , 1 ex. (female, 77.3 mm SL). Towuti , 02°41.335'S, 121°25.897'E; F. Herder & A. Nolte, 29 Nov.2002: ZFMK 44928–44931 , 4 ex. (females, 61.2–65.6 mm SL). Towuti, Timampu, fish market: catch of commercial fishermen collecting small fishes in the pelagic areas of L. Towuti; F. Herder, 15 Apr.2004: ZFMK 44936–44937 , 2 ex. (females, 73–75.7 mm SL). – Nomorhamphus weberi Indonesia, Sulawesi Selatan: Lake Matano , 02°30.149'S, 121°19.416'E; F. Herder, Oct.2002: ZFMK 44924–44927 and 44932–44935, 8 ex. (females, 64.1–73.4 mm SL) .

Figures

Fig. 2. Diagrammatic representation of the modified anal-fin rays (andropodium) of Nomorhamphus rex, MZB 20724, holotype, 44.4 mm SL, male. Fourth segment of the second ray with a dorsal and a ventral row of “subsegments” forming squares and rectangles of different sizes. The fourth ray is divided into three rows from approximately the third of its length, forming a kind of a covering for the third anal-fin ray with one dorsal and two lateral rows beneath. SN, Spinae; SP, Spiculus. Scale bar = 1 mm.

Fig. 3. A, B, Nomorhamphus rex; Indonesia, Sulawesi: Sulawesi Selatan; tributary of Wewu River near the village of Laroeha; 2°28.226'S, 121°04.125'E. A male; B female. C, D, Nomorhamphus rex from Tana Toraja; Indonesia, Sulawesi: Sulawesi Selatan; in a clearwater pool at an excavation of a small river near the village of Tilanga, 3°02.126'S, 119°53.232'E.C male; D female. (Photographs by: Hans-Georg Evers).

Fig. 4.A: Nomorhamphus rex, MZB 20724, holotype, 44.4 mm SL, male; B: ZFMK 44949, paratype, 63.9 mm SL, female.

Fig. 5. Radiograph of Nomorhamphus rex. A, Nomorhamphus rex, MZB 20724, holotype, 44.4 mm SL, male; B, ZFMK 44949, paratype, 63.9 mm SL, female.

Fig. 6. Map of Sulawesi with highlighted sampling locations. Star, sampling location at a tributary of Wewu River near the village of Laroeha; Solid square, sampling location at Toletole River at village Toletole; Solid dot, sampling location close by the village Tilanga in Tana Toraja. (Map by: Thomas von Rintelen, modified).

Fig. 7. Toletole River, type locality of Nomorhamphus rex. (Photography by: Suzanne M. Gray).

Fig. 8. Diagrammatic representation of the caudal skeleton of Nomorhamphus rex, MZB 20724, holotype, 44.4 mm SL, male. EP, Epural; HY, Hypural. Scale bar = 500 μm.