A review of the Distichodus antonii assemblage (Characiformes: Distichodontidae) from the Congo basin Moelants, Tuur Zebe, Victorine Mbadu Snoeks, Jos Vreven, Emmanuel Journal of Natural History 2014 2014-03-03 48 27 - 28 1707 1735 36XLG Nichols and Griscom, 1917 Nichols and Griscom 1917 [367,880,1630,1654] Actinopterygii Distichodontidae Distichodus Animalia Characiformes 20 1726 Chordata species langi    Type material    Holotype. AMNH 5915, Faradje, Dungu region( DRC) (± 3°44′ N, 29°43′ E) ( 364 mmSL).  Note on the original description. Distichodus langihas been described by Nichols and Griscom in 1917 based on one typefrom Faradje and one other specimen with the same data. The current holotypehas a size of 364 mmSL ( 472 mmTL), which does not correspond to the 510 mmSL mentioned by Nichols and Griscom (1917). This latter SL should be considered a lapsus because after verification of the Lang and Chapin collection, no  D. langispecimen of this size has been found. The other specimen mentioned in the original description is reported to measure 325 mmSL, but this also does not correspond to the size of the other specimen ( AMNH7010), which measures 250.7 mmSL, 299.0 mm TL. This specimen has been wrongfully assigned paratypestatus ( Eschmeyer 2013) (see ICZN 1999: article 72.4.6). It has been re-identified as  D. fasciolatusin this review (see above). In the original description, the size of the illustrated specimen ( Nichols and Griscom 1917: plate LXIX) is mentioned as 560 mmTL, which corresponds to a recalculated standard length of 466 mmSL. This does not correspond to either of the two specimensmentioned by Nichols and Griscom (1917). In addition, the drawing does not resemble either of the two specimens. Based on the following counts and observations made on the illustration: 22 circumpeduncular scales; 13 scales between the LL and the dorsal fin, 24 dorsal fin rays and clearly black ventral fins, we assume this illustration represents a specimen from the  D. atroventraliscomplex.  Figure 8.  Distichodus langi(MRAC 2878)from Avakubi (DRC), 300.0 mm SL. (A) Lateral view; (B) Detail of the colour pattern on the adipose fin.   Other material examined   MRAC 2878, Avakubi( DRC) ( 1°19′ N, 27°33′ E) ( 300 mmSL).    Differential diagnosis Within the Congobasin,  D. langican be distinguished from  D. affinis,  D. altus,  D. decemmaculatus,  D. noboli,  D. notospilusand  D. teugelsiby its higher total number of LL scales, i.e. 68–70 (versus <46); from  D.maculatusby the absence of large, dark spots all over the body and a higher number of dorsal fin rays, i.e. 26–28 (versus 19– 21); from  D. antoniiby its inferior (versus terminal) mouth, its higher number of scales between the LL and the dorsal fin, i.e. 15–16 (versus 10–12) and its higher number of LL scales in front of HJ, i.e. 68–70 (versus 52–64); from  D. fasciolatusby its higher number of dorsal fin rays, i.e. 26–28 (versus 24–26); its higher number of pelvic fin rays, i.e. 11 (versus generally 10) and its deeper head, 67.4–69.4 %HL (versus 35.9–62.9 %HL); from  D.lusossoby its inferior (versus terminal) mouth and feebly compressed snout (versus distinctive prolonged); from  D. sexfasciatusby its feebly compressed snout (versus strongly compressed), its higher number of dark vertical bars along the body, i.e. 13 (versus 6–7) and its higher number of teeth on the outer row on both jaws (> 20 versus 12–14) and from the  D. atroventraliscomplex by a higher number of scales between the LL and pelvic fin, i.e. 12 (versus 9–11), its higher number of pectoral fin rays, i.e. 21 (versus 17–20); its higher number of circumpeduncular scales, i.e. 24–25 (versus 20–24) and its deeper head, 67.4–69.4 % HL (versus 35.1–55.7 %HL) ( Table 4).    Description Morphometric and meristic data are given in Table 5. Body relatively deep (within  D. antoniiassemblage). Dorsal head profile and dorsal body outline concave to end of dorsal fin, straight from end of dorsal to adipose fin, and convex from adipose to caudal fin. Ventral head profile straight, concave from posterior to head to end of anal fin, and convex from end of anal to caudal fin. Head compressed with nasal openings relatively closely set (14.4 %HL and 15.9 %HL), but deep (67.4 %HL and 69.4 %HL). Mouth inferior. Posterior edge of maxillary not passing the nostrils. Two rows of bicuspid teeth in each jaw. Origin of dorsal fin well in front of pelvic fin origin along vertical axis. Distal margin dorsal fin straight or slightly concave, distal margin of anal fin straight to slightly convex. Base and distal end of pelvic fin relatively close to vent, i.e. 23.4 %SL and 25.9 %SL, and 1.6 %SL and 7.8 %SL, respectively. Pectoral and pelvic fin rays decreasing in length from outer to inner fin margin. Adipose fin little further removed from dorsal fin than from caudal fin. Caudal peduncle deeper then long. Caudal fin forked with two rounded lobes covered with numerous small scales except for translucent area distally. As only two specimensare currently known from  D. langi, allometry could not be assessed. Maximum recorded length: 364 mmSL, 472 mmTL.   Colouration Lang provided information on the presumable life colour pattern based on five specimens( Nichols and Griscom 1917). It is however unsure whether these specimens are conspecific (see above), and therefore this information is not presented here. The body of the two preserved specimens is uniformly brown-yellowish, with a slightly lighter belly. Dorsal fin scattered with many small, dark spots. Caudal fin brownish, with slightly darker median rays. Adipose fin with translucent distal margin ( Figures 3Cand 8). Pectoral fins pale to yellow-orange. Pelvic fins generally pale, while in the additional specimen the distal edges are darker coloured. Thirteen vague dark vertical bars have been observed on the flanks of the additional specimen, whereas the holotypehas none.    Ecology  Notmuch is known about the ecology of  D. langi. In the original description of Nichols and Griscom (1917), Lang is cited mentioning the following: “Evidently swimming in schools, as five of them have been killed by one explosion”. However, since this original description is based upon three different species (see above), the relevance of this information is difficult to assess.    Distribution  This species is only known from two specimensfrom two different locations, Faradjein the Dungu region, Uele Riverbasin ( DRC) and Avakubi, Aruwimi Riverbasin ( DRC) ( Figure 5).    Etymology The species name “  langi” refers to the collector Herbert Lang (1879–1957), who collected fish in the Congobasin from 1909 to 1915 for the AMNH, in collaboration with James Chapin ( Slack 2003).  List of specimens examined of the D. atroventralis complex (all lengths are SL)( Figure 3D).    Democratic Republic of the Congo(DRC): Syntypes: MRAC 30. Boma( DRC) (± 5°50′ S, 13°03′ E), coll. Wilverth1896 ( 70.9 mm)–  BMNH 1891.12.29.13. Congo River, Lower Congo( DRC), received from Utrecht University Museum1891 ( 63.5 mm); Specimens:  AMNH I-243645. Lulua River, Katende2, Dipumu(± 6° 00′27.0″ S, 22°23′43″ E), coll. Mbimbi  01/12/2007( 64.2 mm; 90.2 mm)–  AMNH I-243646. Lulua River, Nsanga Nyembo(± 5°56′53.41″ S, 22°20′29.40″ E), coll. Mbimbi  03/12/2007( 76.7 mm; 123.3 mm)–  AMNH I-247823. Lulua, Bunkonde( 6°14′49.2″ S, 22°28′48.0″ E), coll. Mbimbi  30/06/2008( 34.4 mm)–  AMNH I-247825. Lulua, Katende1, Nkombua( 6°00′16.2″ S, 22°23′25.8″ E), coll. Mbimbi  21/05/2008(37.0 mm)–  MRAC 158797. Dundo, affl. Luachimo(± 7°21′ S, 20°50′ E), coll. De Barros Machado  02/06/1949( 225.5 mm)–  MCZ50439. Zaire Rivernear Inga, a few km upstream and on the opposite side of river from Ingahydroelectric dam ( 5°27′30″ S, 13°36′??″ E), coll. Robertsand Stewart1973 ( 53.2 mm; 62.8 mm)–  MRAC 738. Banana( 6°00′ S, 12°24′ E), coll. Delhez1899 ( 53.5 mm)–  MRAC 739. Matadi( 5°49′ S, 13°27′ E), coll. Delhez, 1899 ( 246.6 mm)–  MRAC 740. Matadi( 5°49′ S, 13°27′ E), coll. Delhez1899 (66.0 mm)–  MRAC 741. Dolo( 4°19′ S, 15°19′ E), coll. Delhez1899 (357.0 mm)–  MRAC 742. Kutu, (± 2°44′ S, 18°08′ E), coll. Delhez1899 ( 158.3 mm)–  MRAC 67444. Léopoldville(± 4°18′ S, 15°18′ E), coll. Henri van Moorsel7/1944 ( 127.7 mm)–  MRAC 117366. Stanley Pool, Yankauchannel, N’ Dukaindigenous dam (± 4°20′ S, 15°24′ E), coll. MissionBrien-Poll-Bouillon  23/ 9/1957( 199.5 mm)–  MRAC 73-22-P-1195-1197. Stanley Pool, Nsele river(± 4°15′ S, 15°33′ E), coll. Mandeville  29/10/1957( 23.8–41.2 mm)–  MRAC 73-22-P-1201-1202. Stanley Pool, Ndjili river(± 4°20′ S, 15°22′ E), coll. Mandeville  30/10/1957( 67.8 mm; 76.8 mm)–  MRAC 73-22-P-1223. Stanley Pool, Mbamu island(± 4°14′ S, 15°22′ Eto ± 4°18′ S, 15°30′ E), coll. Mandeville J.,  28/10/1957( 33.1 mm)–  MRAC A7-014-P- 0025. Pool Maleboat Kinkole, Mipongi island(± 4°16′26.9″ S, 15°30′29.6″ E), coll. Mbadu Zebe  26/1/2006(128.0 mm)–  MRAC A7-033-P-267. Congo Riverclose to the Kinsangachannel, Inga(± 5°39′ S, 13°39′ E), coll. Hanssens2007 ( 142.6 mm)–  MRACB0-017-P-0020. Lomami River, affluent Congo River, village Lieki, coll. Congo2010  2/06/2010(343.0 mm)–  MRACB0-017-P-0021-0022. Isangi, rive gauche fleuve Congo, coll. Congo2010  5/06/2010( 261.9 mmSL; 325.0 mm SL)–  MRACB0-017-P-0093. Lomami River, left bank, just downstream of village Lieki(± 0°40′55″ N, 24°11′08″ E), coll Exp. Congo2010  27/05/2010( 31.5 mm)–  MRACB0-017-P-0094. Littlemarsh on Lomami River, left bank, upstream of village Yandjambi(± 0°41′57.44″ N, 24°13′36.0114″ E), coll Exp. Congo2010  28/05/2010( 31.4 mm)–  MRACB0-017-P-0095. Lomami River, left bank, upstreamof village Lieki(rive gauche riv. Lomami, en amont du village Lieki(± 0°40′55″ N, 24°11′08″ E), coll Exp. Congo2010  01/06/2010( 61.6 mm)–  MRACB0-017-0096-0097. Lomami River, right bank, downstream of village Lieki(± 0°40′ 55″ N, 24°11′08″ E), coll. Exp. Congo2010  30/05/2010( 21.7 mm; 25.9 mm)–  MRACB0-017-P-0098. Lomami River, downstream of village Lieki(± 0°40′55″ N, 24°11′ 08″ E), coll Exp. Congo2010  27/05/2010(32.0 mm)–  MRACB0-017-0099-0100. Lomami River, downstream of village Lieki(± 0°40′55″ N, 24°11′08″ E), coll. Exp. Congo2010  03/06/2010( 27.6 mmSL; 36.2 mm)–  MRACB0-017-P-0101. Lomami Riverat confluence with Koli River, right bank, downstream of village Lieki(± 0°40′ 55″ N, 24°11′08″ E), coll. Exp. Congo2010  01/06/2010( 25.6 mm)–  MRAC B1-009- P-0022. Lobaye River, left bank, Site2 (± 0°28′28.8″ N, 24°11′57.9″ E), village Bambondji II, coll. Danaduand Moelants  08/05/2011(93.0 mm).    Republic of the Congo( Brazzaville): MRAC A8-020-P-0386-0390 (2/4). Léfini River, “Massala ma soso” rapids, right bank ( 2°55.93′ S, 16°07.42′ E), coll. Vrevenand Ibala Zamba  23/8/2008( 46.5 mm; 68.5 mm). AMNH Democratic Republic of the Congo 3.7333333 Faradje 1307 29.716667 Dungu region 21 1727 AMNH 5915 1 holotype [144,881,1139,1163] MRAC Democratic Republic of the Congo 1.3166666 Avakubi 1308 27.55 22 1728 MRAC 2878 1 Democratic Republic of the Congo Aruwimi River Faradje Avakubi 23 1729 1 DRC Wilverth Democratic Republic of the Congo -5.8333335 Boma 1305 13.05 24 1730 MRAC 30 1 syntype DRC Utrecht University Museum & Specimens Democratic Republic of the Congo Congo River Lower Congo 24 1730 BMNH 1891.12 1 syntype 2007-12-01 AMNH Mbimbi Democratic Republic of the Congo Dipumu -6.0075 Lulua River 15 22.395277 Katende 24 1730 I-243645 1 syntype 2007-12-03 AMNH Mbimbi Democratic Republic of the Congo -5.9481697 Lulua River 1 22.341501 Nsanga Nyembo 24 1730 I-243646 1 syntype 2008-06-30 AMNH Mbimbi Democratic Republic of the Congo -6.2469997 Lulua 1 22.480001 Bunkonde 24 1730 I-247823 1 syntype 2008-05-21 AMNH Mbimbi Democratic Republic of the Congo Nkombua -6.0045 Lulua 1 22.3905 Katende 24 1730 I-247825 1 syntype 1949-06-02 MRAC De Barros Machado Democratic Republic of the Congo -7.35 Dundo 1303 20.833334 Luachimo 24 1730 MRAC 158797 1 syntype MCZ 50439 MCZ Roberts & Stewart Democratic Republic of the Congo Inga -5.458333 Zaire River Inga 24 1730 1 syntype MRAC Delhez Democratic Republic of the Congo -6.0 Banana 1305 12.4 24 1730 MRAC 738 1 syntype MRAC Delhez Democratic Republic of the Congo -5.8166666 Matadi 1305 13.45 24 1730 MRAC 739 1 syntype MRAC Delhez Democratic Republic of the Congo -5.8166666 Matadi 1305 13.45 24 1730 MRAC 740 1 syntype MRAC Delhez Democratic Republic of the Congo -4.3166666 Dolo 1306 15.316667 24 1730 MRAC 741 1 syntype MRAC Delhez Democratic Republic of the Congo -2.7333333 Kutu 1307 18.133333 24 1730 MRAC 742 1 syntype MRAC Henri van Moorsel Democratic Republic of the Congo -4.3 Leopoldville 1306 15.3 24 1730 MRAC 67444 1 syntype 1957-09-23 MRAC Mission Democratic Republic of the Congo Duka -4.3333335 Stanley Pool 1306 15.4 Yankau 24 1730 MRAC 117366 1 syntype 1957-10-29 MRAC Mandeville Democratic Republic of the Congo -4.25 Stanley Pool 1306 15.55 Nsele river 24 1730 MRAC 73-22 1 syntype 1957-10-30 MRAC Mandeville Democratic Republic of the Congo -4.3333335 Stanley Pool 1306 15.366667 Ndjili river 24 1730 MRAC 73-22 1 syntype 1957-10-28 MRAC Mandeville J. Democratic Republic of the Congo -4.3 Stanley Pool 1306 15.5 Mbamu island 24 1730 MRAC 73-22 1 syntype 2006-01-26 MRAC Mbadu Zebe Democratic Republic of the Congo Mipongi island -4.274139 Pool Malebo 1 15.508223 Kinkole 24 1730 A7-014 1 syntype MRAC Hanssens Democratic Republic of the Congo Inga -5.65 Congo River 1305 13.65 Kinsanga 24 1730 A7-033 1 syntype 2010-06-02 MRAC Lieki & Congo Democratic Republic of the Congo Lomami River Congo River 24 1730 1 syntype 2010-06-05 MRAC Congo Democratic Republic of the Congo Isangi Congo 24 1730 1 syntype 2010-05-27 MRAC Exp. Congo Democratic Republic of the Congo 0.6819445 Lomami River 21 24.185555 Lieki 24 1730 1 syntype 2010-05-28 MRAC Exp. Congo Democratic Republic of the Congo Yandjambi 0.6992889 Little 1 24.226671 Lomami River 24 1730 1 syntype 2010-06-01 MRAC Exp. Congo Democratic Republic of the Congo Lieki 0.6819445 Lomami River 21 24.185555 Lomami 24 1730 1 syntype 2010-05-30 MRAC Exp. Congo Democratic Republic of the Congo 0.6819445 Lomami River 21 24.185555 Lieki 24 1730 1 syntype 2010-05-27 MRAC Exp. Congo Democratic Republic of the Congo 25 1731 0.6819445 Lomami River 21 24.185555 Lieki 24 1730 1 syntype 2010-06-03 MRAC Exp. Congo Democratic Republic of the Congo 0.6819445 Lomami River 21 24.185555 Lieki 25 1731 1 syntype 2010-06-01 MRAC Exp. Congo Democratic Republic of the Congo Lieki 0.6819445 Lomami River 21 24.185555 Koli River 25 1731 1 syntype 2011-05-08 MRAC Bambondji II & Danadu & Moelants Democratic Republic of the Congo 0.47466666 Lobaye River 1 24.199415 Site 25 1731 B1-009 1 syntype 2008-08-23 MRAC Vreven & Ibala Zamba Republic of the Congo -2.9321666 Lefini River 13 16.123667 25 1731 A8-020 1 Brazzaville