aqua, International Journal of Ichthyology

Barbus sensitivus, a new species with extensive pitlines from the Sanaga River (Teleostei: )

Tyson R. Roberts

Research Associate, Smithsonian Tropical Research Institute. Email: [email protected]

Received: 29 June 2010 – Accepted: 10 August 2010

Abstract vergleichende Studien unter Einbeziehung von REM- sensitivus new species, from the Sanaga River in Bildern, die Vergleich und Bestimmung ermöglichen. Keine Cameroon, West Africa, has a much more slender caudal der bisher beschriebenen Arten ähnelt dieser neuen Art peduncle than any other small African barb. It also has besonders. Die pitline organelles von B. sensitivus n. sp. extensively distributed exposed pitline organelles in pit lines haben freiliegende oder freie Neuromasten. Ihre Funktion- on the head and scales, illustrated here by scanning electron sweise ist vermutlich mechanosensorisch. Bei der erwachse- micrographs. Similar pit lines and pitline organelles evi- nen B. sensitivus n. sp. sind sie in großen Grubenreihen auf dently occur in various other Old World barbs assigned to Kopf und Rumpf extensiv verteilt; sie ähneln Seitenlinien- various genera in Africa and Asia but adequate comparative Neuromasten bei weit entwickelten Larven von Cyprinus car- studies including SEM observations are not available to pio, Gnathopogon elongatus caerulescens und Danio rerio. permit their comparison and identification. None of the Hauptsächlich sind die Neuromasten auf den ventrolateralen species previously described are very similar to this new Teil des Kopfes konzentriert, wo ihre Zahl rund 30.000 species. The pitline organelles of B. sensitivus n. sp. have beträgt, jeweils mit 20 bis 100 Kinozilien (Flimmerhärchen) exposed or free neuromasts. Their sensory modality pre- mit einer Länge von 7 Mikrometern und 0,4 Mikrometern sumably is mechanosensory. Extensively distributed in large Durchmesser. Grubenreihen mit kleineren -Organellen und pit lines on the head and body of adult B. sensitivus n. sp., weniger Kinozilien finden sich auf den Schuppen des they are similar to lateral line neuromast organs in Rumpfes und auf der Oberseite des Kopfes, fehlen aber auf advanced larvae of Cyprinus carpio, Gnathopogon elongatus den Flossen. Ihr Vorhandensein bei den erwachsenen Tieren caerulescens, and Danio rerio. They are most concentrated der Art B. sensitivus könnte als neotenische Beibehaltung on the ventrolateral part of the head, which has about 3000 (Reste eines früheren Entwicklungsstadiums) aufgefasst wer- of them, most bearing 20 to 100 kinocilia up to 7 micra den. Bei den Larven von Gnathopogon elongatus caerulescens long and 0.4 micra in diameter. Pit lines with smaller pit- dienen derartige Organellen dem Aufspüren von kleiner line organelles and fewer kinocilia occur in rows on the Planktonnahrung wie Artemia während der Nahrungssuche scales of the body and on the dorsal surface of the head but unter verminderten Lichtverhältnissen. are absent from the fins. Their presence in adult B. sensi- tivus new species might represent a neotenic retention. In Résumé larval Gnathopogon elongatus caerulescens they facilitate Barbus sensitivus n. sp., de la rivière Sanaga au Cameroun, detection of tiny planktonic prey such as Artemia when Afrique occidentale, a un pédoncule caudal beaucoup plus feeding under reduced light conditions. mince que n’importe quel autre petit Barbus africain. Il a aussi des organites exposés largement répartis (organites de Zusammenfassung pitline) en pit lines sur la tête et les écailles, illustrés ici par Die neue Art Barbus sensitivus vom Sanaga-Fluss in micrographie électronique scannée. Des pit lines et des or ga - Kamerun, Westafrika, hat einen deutlich schlankeren nites de pitline similaires apparaissent avec évidence sur Schwanzstiel als andere kleine afrikanische Barben. Außer- nom bre d’autres Barbus de l’Ancien Monde, appartenant à dem haben die Vertreter dieser Art in Grübchen, die auf dem des genre différents, en Afrique et en Asie, mais des études Kopf und den Schuppen in Reihen angeordnet sind, frei comparées adéquates, comprenant des observations SEM liegende Organellen („pitline organelles“), die hier durch font défaut pour permettre leur comparaison et identifica- Rasterelektronenmikroskop-Bilder veranschaulicht werden. tion. Aucune des espèces décrites précédemment n’est vrai- Ähnliche Grubenreihen und -Organellen kommen augen- ment semblable à cette nouvelle espèce. Les organites de pit- scheinlich bei anderen Altwelt-Barben vor, in unter- line de B. sensitivus ont des neuromastes exposés ou libres. schiedlichen Gattungen aus Afrika und Asien, doch fehlen Leur mo de de sensibilité est probablement mécanosensoriel.

187 aqua vol. 16 no. 4 - 15 October 2010 Barbus sensitivus, a new species with extensive pitlines from the Sanaga River (Teleostei: Cyprinidae)

Extensivement répartis en larges pit lines sur la tête et le and Tweddle et al. (2006). The sensory papillae corps de B. sensitivus n. sp. adultes, ils sont analogues à des usually are restricted to, or most highly developed neuromastes de la ligne latérale chez les larves à un stade on the lower surfaces of the head. In some, as in the avancé de Cy pri nus carpio, Gnathophogon elongatus caeru le - new species described here, they also occur on the scens et Danio rerio. Ils sont le plus concentrés sur la partie ventrale de la tête qui en compte près de 3.000, la plupart body. They have not been observed on the fins. portant de 20 à 100 kinocíls longs de 7 microns au maxi- In Africa these generally are placed in the mum et d’un diamètre de 0,4 micron. Des pit lines avec les genus Barbus, a catch-all taxon with about 300 organites plus petits et moins de kinocíls apparaissent en species recognized as valid (Daget et al. 1984; rangées sur les écailles du corps et sur la partie dorsale de la Eschmeyer 2010). Several of these African Barbus tête mais sont absentes des nageoires. Leur pré sen ce sur des species sometimes were referred either to Ente - B. sensitivus n. sp. adultes pourrait représenter une persis- romius or Beirabarbus because of their superficial tance néoténique. Au stade larvaire des Gna thopogon elon- sensory papillae but this practice has waned and gatus caerulescens, elles facilitent la détection de fines proies planctoniques, comme les Artemia, quand le nourrissage se currently they are all assigned to Barbus passe sous des conditions lumineuses médiocres. (Eschmeyer 2010). In Asia there are no cyprinids assigned at present Sommario to the genus Barbus, but there are at least three Barbus sensitivus nuova specie, proveniente dal fiume barb-like genera with extensively developed rows of Sanaga in Camerun, Africa occidentale, ha un peduncolo cephalic sensory papillae large enough to be seen caudale molto più esile di ogni altro barbo africano di pic- with the naked eye: Cyclocheilichthys, Eirmotus and cola taglia. Presenta inoltre tipici neuromasti esposti esten- Oreichthys (pers. obs.). As with the African barbs sivamente distribuiti in fossette disposte lungo linee carat- having them, these structures have not yet been teristiche sul capo e sulle scaglie, illustrate qui da fotografie al microscopio elettronico a scansione (SEM). Simili dis- examined with scanning electron microscopy. tribuzioni di questi organelli sono chiaramente presenti in Another point about the presence of possibly sim- varie altre specie di barbi del vecchio mondo, anche asseg- ilar exposed ciliated mechanoreceptors in a variety nati a generi distinte in Africa e Asia, ma un adeguato stu- of Asian as well African barbs is that they may have dio comparativo sulla base di osservazioni al SEM non è al evolved independently, hence may represent an momento possibile. Nessuna delle specie precedentemente ancient recurrent adaptive feature of cyprinoids. descritta appare simile a questa nuova specie. I neuromasti Just how ancient is unclear. Some African and di B. sensitivus n. sp. sono esposti o liberi. La loro funzione Neotropical dischodontid characoids may have sensoriale è probabilmente di tipo meccanocettiva. Esten- sivamente distribuiti in ampie linee di fossette sul capo e il similar organelles. These also have not been ade- corpo dell’adulto di B. sensitivus n. sp., sono simili ai neu- quately studied. romasti della linea laterale in larve in avanzato stadio di Experimental observations indicate that exposed sviluppo di Cyprinus carpio, Gnathopogon elongatus caeru - neuromasts facilitate feeding on zooplankton in lescens e Danio rerio. Essi sono più concentrati sulla por- crepuscular (poorly lit) conditions by larvae of the zione ventrolaterale del capo, che ne ospita circa 3000, cyprinid Gnathopogon elongatus caerulescens (Mukai molti con 20-100 kinocilia fino a 7 micron di lunghezza e et al. 1994; Mukai 2006). Larvae of a variety of dis- 0.4 micron di diametro. Le linee di fossette con neuro- tantly related cyprinids including Cyprinus carpio masti più piccoli e meno kinocilia si trovano in file sulle scaglie del corpo e sulla superficie dorsale della testa ma have exposed pitline organs distributed on the head sono assenti sulle pinne. La loro presenza in adulti di B. and body like those in B. sensitivus. I suggest that sensitivus nuova specie potrebbe rappresentare un tratto the presence of exposed pitline organs in various neotenico. Nelle larve di Gnathopogon elongatus caerulescens lineages of Old World barbines, Asian as well as esse facilitano la rilevazione di minuscole prede planc- African, may result from a widespread neotenic toniche come Artemia in condizioni di scarsa luminosità. tendency to retain exposed pitline organs usually present only in larval stages. In other words, the INTRODUCTION presence of pit lines and of exposed pitline organs A number of small Old World (African and in adults of diverse Old World cyprinids may result Asian) cyprinid fishes or barbs are known with from numerous instances of independent retention extensively developed “sensory papillae” especially of a larval characteristic. For this reason the present on the head. The African ones are documented in new species is assigned to the genus Barbus. At papers by Herre (1936), Barnard (1948), Dejen et such time as the African barbs are generically split, al. (2002), Greenwood (1962), Loiselle & Wel- Enteromius and Beirabarbus are available names, comme (1971), Loiselle (1973), Stewart (1977) and it may be necessary to recognize them both as aqua vol. 16 no. 4 - 15 October 2010 188 Tyson R. Roberts valid. Certainly none of the tropical African barbs Head moderately large and pointed. Snout narrow are truly congeneric with the highly distinctive when viewed from the side, but short and blunt European genus Barbus. viewed from above. Dorsal profile of head evenly convex; no nuchal hump; ventral profile of head from tip of lower jaw to angle of preopercle very Barbus sensitivus n. sp. straight. Mouth termino-inferior, small, rictus of Figs 1-6 jaws lying anterior to a vertical through from mar- gin of eye. Eyes large, oval, dorsally inclined; Holotype (Figs 1-2): CAS 95344, 40 .6 mm, non- orbital length more than one-third head length. tuberculate female, Sanaga River at Belabo, 60 km Nostrils moderately large, lying entirely on half of NW of Bertoua, Cameroon, 4°56’N’, 13°18’E, snout nearest eye. Rostral and mandibular barbels February 1980, Tyson R. Roberts. The river was well developed, rostral barbels slightly longer than very swift, with bottom of coarse gravel and maxillary barbels, about equal to eye diameter. smooth water-worn stones. Rostral barbels originating almost at tip of snout, Paratypes: CAS 95345, 2: 38.1-40.7 mm, tuber- extending posteriorly to just beyond origin of max- culate males, collected with the holotype (40.7- illary barbels. Maxillary barbels extending posteri- mm specimen used for SEM examination). orly from below middle of eyes to slightly beyond Diagnosis: Barbus sensitivus differs from all other them, their anterior halves when adpressed accom- small species of African Barbus by its very slender modated by deep postlabial groove. caudal peduncle. It is distinguished from the great Lateral line complete, nearly straight, slightly majority of small African barbs by its exceptionally curved downwards anteriorly. Scales in lateral line well developed sensory papillae or pitline series 33-35, each with single small lateral line organelles which cover most of the head in both canal pore near middle of its exposed portion. sexes. Similar pit lines occur on the scales covering Scales of entire body nearly uniform in size and the body (not known in other African barbs, but shape, with radiate striae; scales of lateral line series perhaps under-reported). Males differ from those slightly enlarged. Posterior scale margin semicircu- of most other species of African barbs of similar lar or very slightly arched. Predorsal scales 9. Scales size in having the rostrum and dorsal surface of the absent on ventral body surface behind head, head covered with numerous breeding tubercles. including isthmus, to slightly beyond bases of pec- Description: That B. sensitivus is a small barb toral fins. Median abdominal scale rows, from just (and does not grow to a much larger adult size than behind pectoral fin bases to pelvic fin bases, 9. the three specimens reported here) is indicated by Transverse scale rows 5/1/2-3. Circumpeduncular the marked sexual dimorphism of breeding tuber- scales 9. cles on the heads of the two males (paratypes) ver- Dorsal fin very slightly falcate, with 3 simple and sus their absence in the single female (holotype). 8 branched rays. Simple rays very slender and flex- Body subcylindrical, laterally compressed, terete. ible, last simple ray not serrated. Dorsal fin origin

Fig. 1. Barbus sensitivus, 40.6 mm female holotype, Sanaga River at Belabo, Cameroon (CAS 95344). Specimen oriented obliquely in order to show the pit lines on the undersurface of the head and the genital pad to better effect. Photo by J. Fong.

189 aqua vol. 16 no. 4 - 15 October 2010 Barbus sensitivus, a new species with extensive pitlines from the Sanaga River (Teleostei: Cyprinidae) well in advance of vertical line drawn through gin where anteriormost scales insert. Fine melano - pelvic fin origins. Anal fin noticeably more falcate phores forming thin mid-dorsal stripe between than dorsal fin, with 3 simple and 5 branched rays. occiput and dorsal fin origin. Fine melanophores Pectoral fins with one simple and 12-15 branched in elliptic or crescentic patch covering posterior rays. Pelvic fins with one simple and 7 branched half of exposed part of each scale above lateral line rays. Body depth declining more or less regularly scale row; very few much larger melanophores con- from its maximum near dorsal fin origin to end of fined to small area near anteriormost exposed part anal fin base, then evening out; hence transition to of each scale (anteriorly) or to larger area of each slender caudal peduncle very abrupt. Caudal scale (posteriorly). Faint midlateral longitudinal peduncle elongate and slender, its length 2.6-2.8 stripe closely associated with lateral line canal for times its least depth. Caudal peduncle depth 13.4 its entire length composed of few large melano- times in standard length. Caudal fin deeply forked, phores just above and below canal on anterior half with ovate lobes. Principal caudal fin rays 10/9. of body, then same number or slightly more mela- Vertebral counts: The female holotype and intact nophores more evenly distributed over and near male paratype were radiographed in the California canal on its posterior half. Triangular base of cau- Academy of Sciences Department of Ichthyology dal fin overlying hypural fan covered with fine by Jon Fong. The female has 22+17=39 vertebrae melanophores. (Fig. 2), the male 21+18=39. Dorsal fin with small patch of larger melano - Coloration in life: The three specimens phores just in front of and beside its origin. Dorsal (female holotype and two male paratypes), col- fin rays with small melanophores (sometimes lected in two seine hauls in the late afternoon and forming very thin continuous dark streak) along observed alive only briefly an hour or two before anterior and posterior margins of branched and dusk, were white or silvery laterally and ventrally unbranched portions, dorsal fin interradial mar- with strong bluish reflections. No evident mark- gins otherwise without melanophores. Anal fin ings on head, body or fins (midlateral stripe, faint pigmentless except for few melanophores. Paired in preserved specimens, not noticed). Fins color- fins devoid or almost devoid of melanophores. Few less. No sexual dichromatism observed. tiny melanophores along inner margin of outer- Color pattern of preserved speci- most (i.e. simple) pectoral fin ray, pectoral fins oth- m e n s : Head, body and fins without any distinc- erwise without melanophores. Pelvic fins pigment- tive or striking marks, melanophores on fins hardly less. Caudal fin with fine melanophores on edges of visible to unaided eye. Head below middle of eye rays, sometimes also on lepidotrichial joints, ren- and body below lateral line scales row without any dering them more conspicuous. marks and almost devoid of melanophores. Genital papilla: The holotype and only known Numerous fin melanophores on dorsum of snout female specimen, apparently adult, has a pro- and near nostrils, on posterior part of cranial roof nounced genital pad (Fig. 1). This might indicate over expanded portion of brain, and on opercular that only one or a few eggs are laid at a time and insertion. Fine melanophores along occipital mar- that the eggs are relatively large.

Fig. 2. Barbus sensitivus, 40.6 mm female holotype, Sanaga River at Belabo, Cameroon (CAS 95344). Radiograph by J. Fong. aqua vol. 16 no. 4 - 15 October 2010 190 Tyson R. Roberts

Distribution: Barbus sensitivus is known only from ing later ichthyological survey work in Cameroon the three specimens collected in the Sanaga River in (Randall E. Brummett, Cameroon Project, 1980. No additional specimens were collected dur- World Fish Center, pers. comm., 4 Jan 2007).

Fig. 3a-b. Barbus sensitivus, 40.7 mm male paratype, Sanaga River at Belabo, Cameroon. a, lateral view; b, ventral view (length of head from snout tip to end of opercle 10.1 mm).

191 aqua vol. 16 no. 4 - 15 October 2010 Barbus sensitivus, a new species with extensive pitlines from the Sanaga River (Teleostei: Cyprinidae)

Etymology: The name “sensitivus” is from the jecting straight up. Micrographs were taken on the Latin sintio, sensus, to perceive by the senses or feel, left side of the specimen except for overall views of in reference to the numerous pitline sensory the ventral surface of the head and dorsal view of organelles characteristic of this species. snout. SEM observations of epidermal structures Breeding tubercles: The two male paratypes have Methods: The three specimens of the new species exceptionally large and numerous breeding tuber- were collected alive and immediately preserved in cles for such a small species, another character 10% formalin. They were not removed from the which may distinguish B. senstitivus from most formalin until five years later, when one male spec- other small African barbs (Figs 3-5). The tubercles imen was selected and processed for SEM observa- on the head occur mainly on the rostrum and on tion. Dehydration was done by gradually bringing the dorsal surface of the snout. Those on the ros- the specimen up from deionized water to absolute trum have their apices directed laterally. In the one alcohol. The specimen was then cut in half at the male studied with SEM, the dorsal rim of each middle of the dorsal fin, the halves freeze-dried and nostril has five fairly large tubercles in two groups, gold-coated. The anterior half was mounted on a an anterior group of three somewhat larger tuber- stub by its cut surface with its head projecting cles and a posterior group of two much smaller straight up, and the posterior half with the tail pro- tubercles. A very few additional small tubercles are

Fig. 4a-c. Barbus sensitivus, 40.7 mm male paratype. a. Lateral view of snout with breeding tubercles and pit lines; b. pitline organelles on head, scale bar = 1 micron; c. pitline organ on head, scale bar = 5 micra.

Fig. 5a-b. Barbus sensitivus, 40.7 mm male paratype. a-b. dorsal view of snout.

aqua vol. 16 no. 4 - 15 October 2010 192 Tyson R. Roberts found on the snout between the nostrils. Particu- pitline organelles on the dorsal surface of the head. larly striking is the large number of shallow tuber- These were not adequately recorded during the cle craters on the snout and posteriorly on the head SEM work and are not included in the following between the eyes where almost no developed tuber- quantitative observations. cles are present. This particular specimen may have Counting pitline organelles on the ventrolateral recently shed most of the tubercles on the dorsal and ventral surfaces of the head of the 40.7 mm surface of its head posterior to the rostrum and male yielded 1389 on the left side of the head. nostrils. This suggests that it may have recently Doubling this number provides an estimated total been in spawning condition, spawned, and then number of 2,800 pitline organelles on the ventral shed most of the tubercles previously present. and ventrolateral surfaces of the entire head. The largest tubercles, on the snout, about 120 Pit lines are present on all of the scales in the lat- micra high and 300 micra in diameter, are com- eral line scale row and the scale row immediately posed of several hundred cells, while the small above it, on nearly all of the scales on the scale row tubercles on the pectoral fins are composed of directly below it and on a few of the scales in the about two dozen cells and are only 20-30 micra second and third rows above the lateral line scale high. They are arranged in 4-5 rows on each inter- row (Fig. 6). A direct count of pitline organs on the radial membrane. Epidermis on the dorsal surface scales on the left side of the body of the 40.7 mm of the fin rays is non-tuberculate, consisting of flat- male yielded 903. Allowing for about a dozen miss- tened hexagonal cells with well developed ing scales in the middle of the body, including a microvilli or microvillar ridges with an average of few lost when the body was cut in two or covered about one pore (presumably a mucus pore) for with mounting media, the estimated total for the every two cells. left side is 1,000-1,050. Doubling these numbers Tubercles of basically similar morphology, con- gives an estimated total of 2,000-2,100 pitline sisting of relatively small numbers of epidermal organs on the body. cells, occur on the dorsal surface of the pectoral Distribution of the pit lines on the head appar- fins of the males. The female has no tubercles on ently follows a highly complex pattern not only the head or on the pectoral fins. characteristic of adults of B. sensitivus but also of Pit lines. The pit lines with their sensory papillae the larvae of some other cyprinids. The main char- or ciliated pitline organs are even more evident acteristics of these are: 1) a major system with a sin- than the tubercles. They are apparently restricted gle continuous main line parallel to the lower to the head and body (absent from barbels and mandibular-posterior circumorbital margin, from fins). On the head they occur mainly in grooves or which numerous lesser curved lines radiate towards furrow on the ventrolateral surface. There also are the eye ; 2) a smaller continuous main line parallel numerous smaller pitline rows with much smaller to the lower margin of the anterior circumorbital

Fig. 6a-c. Barbus sensitivus, 40.7 mm male paratype. a-c, scales with pit lines. Note lateral line pores in middle scale row.

193 aqua vol. 16 no. 4 - 15 October 2010 Barbus sensitivus, a new species with extensive pitlines from the Sanaga River (Teleostei: Cyprinidae) margin, with similar curved lines radiating on the that it evolved independently or that it re-appeared side of the mouth in front of the eye; 3) three or repeatedly in adults of small African barbins, and four large nearly vertical lines directly upwards that therefore those species possessing it may not from the ventral margin of the preopercle; 4) a form a phyletic lineage, apparently has not been number of variable lines directed upwards from the considered before now. ventral margin of the opercle; and 5) an elongate Type locality and trivial name of Enteromius po - oval patch of numerous close-set small pitline ta mogalis: A long-standing confusion confusion organelles on the ventral gular area between the about the type locality of E. potamogalis (Daget et mandibular rami. al. 1984; Böhlke 1984; Eschmeyer 2010) should The distribution and morphology of the pit lines be clarified. A remark also is in order concerning and pit line organelles of adult B. sensitivus are sim- the origin of the specific name “potamogalis”. In the ilar to those of the pit lines and their organelles in original description Cope stated “This species was larvae of Cyprinus carpio (Applebaum & Riehl procured by the African traveler, P. B. Duchaillu 1997), Gnathopogon elongatus caerulescens (Mukai [sic], in streams and rivulets fifty to sixty miles & Kobayashi 1995) and Danio rerio (Webb & north of the equator, and the same distance from Shirey 2003). the ocean.” This location has been identified as “Gaboon? (Daget et al. 1984: 219) and as “French DISCUSSION Congo, streams and rivulets 50 to 60 mi N of the Status of nominal African barbin genera equator, and the same distance from the ocean” Beirabarbus and Enteromius: Beirabarbus Herre, (Böhlke 1984: 87). Bill Eschmeyer simply cites the 1936 (type species Beirabarbus palustris Herre, type locality as provided by Cope: “Streams and 1936, by original designation and monotypy) was rivers 50-60 miles north of the equator and same distinguished by its author primarily on the basis distance from the ocean, West Africa” (Eschmeyer of having cephalic pit lines. It was recognized as a 2010). valid subgenus of Barbus by Greenwood (1962: The American Paul Belloni Du Chaillu (1831- 193), who noted the presence of pit lines on the 1903) is known chiefly for his early explorations in scales, and identified the pitline organs as neuro- Gabon and Rio Muni, during which he discovered masts based on unpublished histological observa- numerous undescribed birds and mammals and tions by P. J. Whitehead. If Beirabarbus is recog- obtained the first complete skeletons and skins of nized, B. sensitivus might be referable to it. Gorilla gorilla. Narrative accounts of his African Enteromius Cope, 1869 (type species Enteromius travels occur in two books, Explorations and Adven- potamogalis Cope, 1869, by original designation tures in Equatorial Africa (1861) and A Journey to and monotypy) was identified as a senior synonym Ashango-Land: and Further Penetration into Equato- of Beirabarbus by Karaman (1970: 189). Karaman rial Africa (1867). The first described a journey in based this synonymy on the identification of E. July-August 1856 up the river Rio Muni and on up potamogalis as a junior synonym of Barbus the Muni tributaries and on up its tributaries the (=Beirabarbus) ablabes Bleeker, 1863. This identifi- Ntambonay (=Temboni or Utamboni) and Noon- cation originated with Boulenger (1911: 156) and day (Du Chaillu, 1861, Chapter IV). Of his is mistaken. My examination of 8 of the 17 origi- recorded travels, this corresponds best to the nal syntypes of E. potamogalis deposited in the description “50 to 60 miles N of the equator and Academy of Natural Sciences of Philadelphia an equal distance from the ocean.” Part of the (ANSP 7607) indicates that it is distinct from B. Ntambounay travelled by Du Chaillu is in fact ablabes, although it might be a Beirabarbus. Pit only about 60 miles N of the equator. At this point lines on the head are relatively few, and there seem he would have been only some 20 or 30 miles to be none on the scales. inland, but anyone familiar with cross-country Beirabarbus also was recognized as a senior syn- travel in this densely forested and very rocky coun- onym of Enteromius by P. H. Greenwood (Green- try will know how difficult it is to calculate precise wood 1970: 10-12), because the type species of distances travelled, as Du Chaillu explains in the both nominal genera or subgenera had a “peculiar” preface to the second book on his travels in equa- cephalic pitline system. This system still has not torial Africa (Du Chaillu 1867: vii). been adequately studied in any of the species That he recorded distances travelled carefully is referred to these nominal genera. The possibility evident from Du Chaillu’s description of his travel aqua vol. 16 no. 4 - 15 October 2010 194 Tyson R. Roberts on the river Ntambounay. Shortly after 27 July Fonds Leopold III pour la Conservation et la 1856 he entered the Ntambounay, ascending 20 Exploration de la Nature; the late Jean-Pierre miles in an ESE direction, then 29 miles up the it Gosse kindly helped me obtain this grant. The and into the Noonday River, which he then resulting collections are deposited in the California ascended for an additional 12 miles (Du Chaillu, Academy of Sciences. The paper was prepared in 1867). Modern maps show that the Ntambounay the Department of Ichthyology of the California (or Tamboni or Utamboni) courses for some 20 Academy of Sciences and in the Center for Con- miles ESE before it bends abruptly to ENE. At this servation Biology, Institute for Molecular Bio- point it is about 60 miles N of the equator and 40 sciences, Mahidol University, Nakhon Pathom, miles inland. Fish or fishing activities are men- Thailand. The holotype was photographed and the tioned at least twice in this part of the narrative, holotype and one paratype radiographed by Jon including an incident shooting fish with a rifle Fong in the Department of Ichthyology, California which caused a stampede of elephants. Du Chaillu Academy of Sciences. Scanning electron did not actually record preserving any fish speci- microscopy was done by Darryl Ubick and the mens. author using the Academy’s SEM facility. Funding The type specimens of E. potamogalis apparently for SEM work was provided by the Research Fund are the only fish specimens he collected during this of the California Academy of Sciences; the author trip; at least no other specimens were deposited in is grateful to William N. Eschmeyer and Patrick J. the fish collection of the Academy of Natural Sci- Kociolek for arranging this funding. Jacqueline F. ences of Philadelphia (W. B. Saul, pers. comm., 10 Webb, Biology Department, Villanova University, July 1997). The river Rio Muni is in what is now commented on an early version of the manuscript, officially known as the Republic of Equatorial particularly on identification of the pitline Guinea (formerly the country of Rio Muni). organelles. Nearly the entire country is occupied by the basin of the river Rio Muni. Although Karaman (1970) REFERENCES suggested it is a junior synonym of Barbus camta- APPELBAUM, S. & RIEHL, R. 1997. Scanning electron canthus, Enteromius potamogalis probably is a valid microscopic observations of the chemo and mechanore- species, perhaps endemic to the Rio Muni basin, or ceptors of carp larvae (Cyprinus carpio) and their rela- to the Rio Muni and Ogooué and smaller river sys- tionship to early behavior. Aquatic Living Resouces 10: tems adjacent to them. It may be referred to as Bar- 1-12. bus potamogalis. BARNARD, K. H. 1948. Report on a collection of fishes from the Okavango River, with notes on Zambesi fishes. In naming his new species Enteromius potamo- Annals of the South African Museum 36 (5): 407-458. galis, Cope (1869) did not provide any explanation BLEEKER, P. 1863. Mémoire sur les poissons de la côte de for the generic or species terms. “Enteromius” pre- Guinée. Natuurkundige Verhandelingen van de Holland- sumably refers to the intestine, which Cope con- sche Maatschappij der Wetenschappen te Haarlem (Ser. 2) sidered to be comparatively short. He did not men- 18: 1-136, pls 1-28. tion the cephalic pitline system. The species or triv- BÖHLKE, E. B. 1984. Catalogue of the type specimens in ial name “potamogalis” evidently refers to a highly the ichthyological collections of the Academy of Natural distinctive fish-eating mammal, the West African Sciences of Philadelphia. Academy of Natural Sciences of Philadelphia Special Publication 14, viii+246 pp. water shrew Potamogale velox Du Chaillu (1868). BOULENGER, G. A. 1911. Catalogue of the Fresh-water Cope presumably knew of the fish-eating habits of Fishes of Africa in the British Museum (Natural History). this directly from the explorer also from the London. Volume 2: i-xii + 1-529. fine print of a Potamogale on the bank a river with COPE, E. D. 1869. Supplement on some new species of a large barb in its forepaws on the title page of Du American and African fishes. Transactions of the American Chaillu’s second book on his African travels. Philosophical Society 13 (2): 400-407. DAGET, J., GOSSE, J. P. & THYS VAN DEN AUDENAERDE, D. ACKNOWLEDGEMENTS F. E. (Eds). 1984. Check-list of the freshwater fishes of Africa. ORSTOM-MRAC., vol. 1, xviii+410 pp. The Ministry for Scientific and Technological DEJEN, E., RUTJES, H. A., DE GRAAF, M., NAGELKERKE, L. Research of the Federal Republic of Cameroon A. J., OSSE, J. W. M. & SIBBING, F. A. 2002. The ‘small granted permission to the author to do fieldwork barbs’ Barbus humilis and B. trispilopleura of Lake Tana and collect fish specimens for scientific study in (Ethiopia): are they ecotypes of the same species? Envi- 1980. Fieldwork was funded by a grant from the ronmental Biology of Fishes 65 (4): 373-386.

195 aqua vol. 16 no. 4 - 15 October 2010 Barbus sensitivus, a new species with extensive pitlines from the Sanaga River (Teleostei: Cyprinidae)

DU CHAILLU, P. B. 1861. Explorations and Adventures in LOISELLE, P. V. & WELCOMME, R. L. 1971. Two new Equatorial Africa. New York, Harper and Brothers, 531 species of Barbus (Pisces: Cyprinidae) from southeastern pp., map. Dahomey. Revue de Zoologie et de Botanique Africaines 83 DU CHAILLU, P. B. 1867. A Journey to Ashango-Land: and (1-2): 1-15. Further Penetration into Equatorial Africa. New York, D. MUKAI, Y., YOSHIKAWA, H. & KOBAYASHI, H. 1994. The Appleton and Co., xxiv+501 pp., map. relationship between the length of the cupulae of free neu- ESCHMEYER, W. N. 2010. Catalog of Fishes. California romasts and feeding ability in larvae of the willow shiner Academy of Sciences (online; last revised 6 May 2010). Gnathopogon elngatus caerulescens (Teleostei, Cyprinidae). GREENWOOD, P. H. 1962. A revision of certain Barbus Journal of Experimental Biology 197: 399-403. (Pisces, Cyprinidae) from East, Central, and South MUKAI, Y. & KOBAYASHI, H. 1995. Development of free Africa. Bulletin of the British Museum (Natural History) neuromasts with special reference to sensory polarity in 8(4): 153-208. larvae of the willow shiner, Gnathopogon elongatus GREENWOOD, P. H. 1970. A revision of the cyprinid caerulescens (Teleostei, Cyprinidae). Zoological Science 12: species Barbus (Enteromius) radiatus Peters, 1853, with a 125-131. note on the synonymy of the subgenera Beirabarbus and MUKAI, Y. 2006. Role of free neuromasts in larval feeding Enteromius. Revue de Zoologie et Botanique africaine 82 of willow shiner Gnathopogon elongatus caerulescens (1-2): 1-12. Teleostei, Cyprinidae. Fisheries Science 72(4): 705-709. HERRE, A. W. C. T. 1936. A new cyprinid genus and STEWART, D. J. 1977. Geographic variation of Barbus species and a new characin from Portuguese East Africa. radiatus Peters, a widely distributed African cyprinid fish. Proceedings of the Biological Society of Washington 49: 99- Environmental Biology of Fishes 1 (2): 113-125. 101. TWEDDLE, D., BALIRWA, J., MACLENNAN, D., OKARONON, KARAMAN, M. S. 1971. Süsswasserfische der Turkei. 8. J., TUMWEBAZE, R., GETABU, A. & BASSA, S. 2006. Teil. Revision der Barben Europas, Vorderasiens und Occurrence of Barbus profundus Greenwood 1970 Nordafrikas. Mittheilungen Hamburgischen Museum und (Telostei: Cyprinidae) in mid-water in Lake Victoria. Institute 67: 175-254. African Journal of Aquatic Science 31 (1): 155-157 LOISELLE, P. V. 1973. Description of a new species of Bar- WEBB, J. F. & SHIREY, J. E.. 2003. Postembryonic devel- bus (Pisces Cyprinidae) from West Africa. Revue de Zoolo- opment of the cranial lateral line canals and neuromasts gie et de Botanique Africaines 87 (2): 379-390. in zebrafish. Developmental Dynamics 228: 370-385.

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