Enteromius walshae, Mamonekene & Zamba & Stiassny, 2018

Mamonekene, Victor, Zamba, Armel Ibala & Stiassny, Melanie L. J., 2018, A new small barb (Cyprininae: Smiliogastrini) from the Louesse, Lekoumou (upper Niari basin), and Djoulou (upper Ogowe basin) rivers in the Republic of Congo, west-central Africa, American Museum Novitates 2018 (3917), pp. 1-16 : 4-13

publication ID

https://doi.org/ 10.1206/3917.1

persistent identifier

https://treatment.plazi.org/id/4B6E603C-FFA6-5248-71D8-FCB7FE5E0E52

treatment provided by

Carolina

scientific name

Enteromius walshae
status

new species

Enteromius walshae , new species

Figures 2, 3; table 3

HOLOTYPE: AMNH 266856 View Materials , female, 52.7 mm SL, Republic of Congo, Niari Province , Mayoko County, Tributary of Mandoro River (2°17′38.6″ S, 12°51′56.8″ E), G. Walsh et al., 10 January 2012. GoogleMaps

PARATYPES: AMNH 266857 View Materials , 3 specimens, 1 C&S, 41.3–51.2 mm SL, same data as holotype GoogleMaps . — AMNH 266805 View Materials , 5 specimens, 30.1–43.2 mm SL, same locality as the holotype, G. Walsh et al, 18 October 2013 GoogleMaps . — OS 22280 , 2 specimens, 49.7–50.1 mm SL, Republic of Congo, Niari Province , Mayoko County, Tributary of Mandoro River (2°17′57.3″ S, 12°46′6.2″ E), G. Walsh et al., October 2013 GoogleMaps . — MRAC 2018-027 View Materials -P-0001-0002, 2 specimens, 36.8–37.1 mm SL, Republic of Congo, Niari Province , Mayoko County, Tributary of Mandoro River (2°19′07″ S, 12°49′46″ E), G. Walsh et al., October 2013 GoogleMaps . — ZSM 47362 View Materials , 2 specimens 31.6–38.5 mm SL, Republic of Congo, Lekoumou River at bridge (3°22′49.3″ S, 13°15′55.0″ E) GoogleMaps , V. Mamonekene , 8 December 2010 . — AMNH 266858 View Materials , 2 specimens, 42.5–51.1 mm SL, Republic of Congo, Niari Province , Tsinguidi County, Loula River (2°26′48.9″ S, 12°58′21.9″ E), G. Walsh et al., 18 November 2013 GoogleMaps . — AMNH 266806 View Materials , 4 specimens, 36.1–53.7 mm SL, Republic of Congo, Niari Province , Tsinguidi County, Tributary of Mandoro River (2°24′24.1″ S, 12°56′55.0″ E), G. Walsh et al., 13 November 2013 GoogleMaps . — AMNH 266808 View Materials , 2 specimens, 34.0– 52.1 mm SL, Republic of Congo, Niari Province , Tsinguidi County, Tributary of Mandoro River (2°25′27.2″ S, 12°53′19.8″ E), G. Walsh et al., 18 October 2013 GoogleMaps . — AMNH 266859 View Materials , 3 specimens, 28.2–41.3 mm SL, Republic of Congo, Niari Province , Mayoko County, Louesse River (2°14′29.5″ S, 12°47′38.3″ E), G. Walsh et al., 10 January 2012 GoogleMaps . — AMNH 266860 View Materials , 6 specimens, 3 C&S, 31.1–40.5 mm SL, Republic of Congo, Niari Province , Mayoko County, Lekoumou River at bridge (3°22′49.3″ S, 13°15′55.0″ E) GoogleMaps , V. Mamonekene , 8 December 2010 . — AMNH 266861 View Materials , 4 specimens, 38.2–53.2 mm SL, Republic of Congo, Niari Province , Mayoko County, Bakoulou River (2°16′58.6″ S, 12°48′23.3″ E), G. Walsh et al., 10 January 2012 GoogleMaps . AMNH 266862 View Materials , 5 specimens, 2 C&S, 36.1–53.2 mm SL, Republic of Congo, Niari Province , Djoulou River at bridge (2°33′31.8″ S, 13°34′30.0″ E) GoogleMaps , V. Mamonekene , 4 December 2010 .

DIFFERENTIAL DIAGNOSIS: While no unambiguous morphological autapomorphies have been located to diagnose Enteromius walshae the species is nonetheless readily distinguished from all congeners by the presence of a flexible, weakly ossified, and smooth-bordered last unbranched dorsal-fin ray, well-developed barbels, and a straight and complete lateral line in combination with a characteristic pigmentation patterning consisting of a distinctive, rounded black spot at the base of and extending over the first rays of the anal fin and a prominent, darkly pigmented blotch over the base of the anterior dorsal-fin rays.

DESCRIPTION: A small Enteromius species attaining a maximum recorded size of 53.7 mm SL (mature female, AMNH 266806 View Materials ), with general appearance as in figure 2. (See table 3 for proportional measurements and meristic counts for the holotype and 40 paratypes.) Body moderately elongate, laterally compressed, although belly of ripe females often distended. Head small, eyes large, mouth subinferior, two pairs of barbels. In smaller specimens (<35 mm SL) maxillary barbels extend to anterior third of eye, mandibular pair reach just beyond posterior margin of orbit. In larger specimens, maxillary pair extends posterior to level of mideye, mandibular pair reaches anterior border of preopercle. No tubercles or sensory pit lines present. Cranium fully ossified with no open occipital fontanel. Five infraorbitals ( IO): IO1 deepest of the series, IO2–5 tubular (compare panel A with panels B and C of fig. 3), with medially located infraorbital canal. Scales radially striated, 23–26 in lateral line (+1–2 over caudal-fin base), 4.5/1/3.5 transverse body rows, 11 circumpeduncular rows (rarely 12), 8.5–9.5 predorsal scale rows. Lateral line complete, located along midline with pored scales not enlarged relative to those along impinging rows above and below .

Dorsal fin iii.8, positioned midway between snout and caudal-fin base, origin at, or slightly anterior to, pelvic-fin insertion. Last unbranched ray long and weakly ossified, segmented distally, and lacking serrations along posterior border (fig. 3D). Anal fin iii.5 (rarely iii.6), forked caudal fin, 9 + 10 principal rays, 6–8 + 7–9 procurrent rays. Pelvic fin i.7, pectoral fin i.12–13. Gill rakers small, 4–6 restricted to distal portion of ceratobranchial and epibranchial of first arch.

Total vertebrae 30–31, 16–17 abdominal, 14–15 caudal (holotype 31, 17+14). Eleven or 12 pleural ribs, 4 (rarely 5) broad supraneurals located between and filling the interspaces of neural spines of vertebral centra 4–8 (compare fig. 3D and E). First dorsal-fin pterygiophore between neural spines of vertebral centrum 8–9, and first anal-fin pterygiophore directed at hemal spine of vertebral centra 17–19. Caudal-fin rays supported by neural and hemal spines of preural centra 2–3. Pleurostyle, single epural, parhypural + seven hypural elements present.

COLORATION: In preservation (fig. 2A, C), base body coloration cream or creamy yellow, darker dorsally, becoming paler ventrally over belly, cheeks, and lower jaws. Snout and dorsum of head heavily pigmented and dark, opercular blotch usually well developed. Prominent lateral band overlies a somewhat zigzag-patterned midlateral scale series. Lateral band widest anteriorly, becoming somewhat attenuated posteriorly, terminating in round or ovoid caudal spot over line of caudal flexion, not extending onto caudal fin. Darkly pigmented blotch over base of anterior dorsal-fin rays. Prominent, rounded black spot at anterior base of, and extending onto, first few anal-fin rays. Fins otherwise pale gray or hyaline. Base coloration in life somewhat variable, either predominately silvery (fig. 2B) or golden (fig. 2D). Opercular blotch and midlateral band only faintly visible, black pigmentation at anterior base of dorsal, anal and caudal fins strongly marked.

GUT MORPHOLOGY AND DIET: Digestive tract long and looped; esophagus leads to small, thin-walled stomach. Intestine exits directly from distal end of stomach, forms primary loop passing posteriad almost to anus, looping back anteriad to pass under stomach forming a secondary loop extending posteriad to anus (fig. 2E). Total length of tract (unraveled but not stretched) ca. 1.3–1.5 times SL. Review of gut contents in preserved specimens indicates E. walshae feeds principally on detritus and organic debris. Guts contain detritus, sand grains, some chironomid larval head cases and other fragmented, unidentifiable insect remains.

REPRODUCTION: Sexually mature at small size; largest female containing ripe eggs, 32.5 mm SL (AMNH 258816). Adult females generally attaining larger sizes than males (largest female, 53.7 mm SL, AMNH 266806; largest male, 51.0 mm SL, AMNH 266807). Most individuals collected October–February had ovaries filled with numerous small, round eggs or enlarged testes, suggesting a protracted reproductive period at commencement of and during rainy season. Water levels are high and water is extremely turbid in large rivers during this period; however, most specimens were collected in small, forested streams where water levels remain low throughout most of the rainy season.

DISTRIBUTION: Found in forested streams and rivers throughout the surveyed region (fig. 4A). Commonly encountered in tributaries and subtributaries of the Louesse River in the Niari basin, and in the Djoulou River, a tributary of the upper Ogowe. The species is not found in tributaries of the lower Kouilou-Niari or in coastal basin systems in the Republic of Congo ( Walsh et al., 2014). Although no data are currently available, we anticipate that further collecting in the upper Ogowe basin will extend the species’ distributional range into adjacent forested regions of that basin in Gabon.

ETYMOLOGY: We name this new smiliogastrin cyprinid for our colleague Gina Walsh (University of Witwatersrand, South Africa), whose ongoing research continues to enhance conservation efforts throughout the region.

COMPARATIVE MATERIALS EXAMINED: Enteromius atakorensis: AMNH 226419, 4 specimens, Guinea, Creek crossing highway between Parakou and Ndali.

Enteromius atromaculatus: AMNH 6295, holotype, Democratic Republic of Congo, Yakuluku Port , Uele River, Ubangi basin.

Enteromius barotseensis: AMNH 269055, 4 specimens, Democratic Republic of Congo, Lulua River   GoogleMaps at Kayala (7°44′21.7″S, 22°36′39.6″ E).

Enteromius baudoni: AMNH 257020, 6 specimens, Guinea (9°46′56.4″ S, 10°38′06.9″ E).

Enteromius bifrenatus: AMNH 269058, 28 specimens, Democratic Republic of Congo, Lulua River   GoogleMaps 150 km from Angolan border (9°42′43.2″ S, 22°51′11.4″ E).

Enteromius brichardi: AMNH 254008, 1 specimen, Republic of Congo, Niari Province   GoogleMaps , Passi-Passi River (3°51′58.4″ S, 12°20′47.2″ E).

Enteromius camptacanthus: AMNH 256531, 6 specimens, Republic of Congo, Niari Province   GoogleMaps , Mandoro River (2°17′59.2″ S, 12°51′59.1″ E). — AMNH 256416 View Materials , 8 specimens, 2 C&S, Republic of Congo, Niari Province , Mayoko County, Tributary of Mandoro River (2°19′37.4″ S, 12°49′58.8″ E) GoogleMaps .

Enteromius catenarius: AMNH 266863, 8 specimens, 1 C&S, Republic of Congo, Bouenza Province , Nkendala River , near Boko Songho. — AMNH 266868 View Materials , 6 specimens, 1 C&S, Republic of Congo, Bouenza Province , Bodi River, near Boko Songho.

Enteromius chiumbeensis: AMNH 258901, 19 specimens, Republic of Congo, Niari Province, Mayoko County, Tributary of the Mandoro River (2°19′06.9″ S, 12°49′46.7″ E). — AMNH 256477 View Materials , 11 specimens, 2 C&S, Republic of Congo, Niari Province .

Enteromius diamouanganai: AMNH 263062, 6 specimens, Republic of Congo, Kouilou Province, Kigongo River (4°33′39.5″ S, 12°06′30.4″ E) . — AMNH 263139 View Materials , 2 specimens, Republic of Congo, Kouilou Province , Mambana River (4°32′53.3″ S, 12°06′01.5″ E) GoogleMaps . — AMNH 253883 View Materials , 1 specimen, Republic of Congo, Kouilou Province , Kouilou-Niari River at Sounda (4°04′48.5″ S, 12°08′18.4″ E) GoogleMaps .

Enteromius guirali: AMNH 253881, 4 specimens, Republic of Congo, Kouilou Province   GoogleMaps , Kouilou-Niari River at Sounda (4°04′48.5″ S, 12°08′18.4″ E). — AMNH 253941 View Materials , 2 specimens, Republic of Congo, Niari Province , Kouilou-Niari River at Loudima (4°06′01.0″ S, 13°03′38.0″ E) GoogleMaps .

Enteromius haasianus: AMNH 269072, 2 specimens, Democratic Republic of Congo, Lulua River   GoogleMaps 150 km from Angolan border (9°42′43.2″S, 22°51′11.4″ E).

Enteromius holotaenia: AMNH 253870, 2 specimens, Republic of Congo, Lekoumou Province   GoogleMaps , Djoulou River (2°33′31.8″S, 13°34′30.0″ E). — AMNH 258144 View Materials , 6 specimens, Republic of Congo, Kouilou Province, at Tissa (4°8′44.4″ S, 11°42′48.1″ E) — AMNH 250765 View Materials , 8 specimens, 2 C&S, Democratic Republic of Congo, Small stream flowing into main channel of the N’Sele (4°26′41″ S, 15°41′00″ E).

Enteromius jae: AMNH 256447, 1 specimen, Republic of Congo, Lekoumou Province   GoogleMaps , River Kessampo   GoogleMaps (2°46′25.9″ S, 13°48′56.7″ E). — AMNH 253889 View Materials , 2 specimens, Republic of Congo, Lekoumou Province   GoogleMaps , Lekoumou River (3°22′49.3″ S, 15°48′55.0″ E) — AMNH 253857 View Materials , 29 specimens, 3C&S, Republic of Congo, Djoulou River at bridge (2°33′31″ S, 13°34′30″ E).

Enteromius kuiluensis: AMNH 253891, 64 specimens, 3 C&S, Republic of Congo, Lekoumou Province, Lekoumou River (3°22′49.3″ S, 15°48′55.0″ E). — MNHN 1929-0243 View Materials , syntype, Gabon, Kouilou River .

Enteromius lineomaculatus: AMNH 271043, 2 specimens, Tanzania, Uvinza   GoogleMaps salt works near Nkwasa (5°5′52.5″ S, 30°21′16.2″ E).

Enteromius macinensis: AMNH 257726, 4 specimens, Guinea (9°41′36.8″ S, 10°9′4.4″ E).

Enteromius martorelli: AMNH 253985, 5 specimens, Republic of Congo, Niari Province   GoogleMaps , Lebayi River (2°39′56.6″ S, 13°35′45.0″ E). — AMNH 256509 View Materials , 10 specimens, 2 C&S, Republic of Congo, Niari Province , at Comilog (2°13′27.4″ S, 12°49′10.8″ E) GoogleMaps .

Enteromius nigroluteus: AMNH 253888, 5 specimens, Republic of Congo, Lekoumou Province   GoogleMaps , Lekoumou River (3°22′49.3″ S, 15°48′55.0″ E).

Enteromius prionacanthus: AMNH 258881, 2 specimens, Republic of Congo, Niari Province, Mandoro River (2°19′53.7″ S, 12°49′42.3″ E) . — AMNH 256523 View Materials , 17 specimens, Republic of Congo, Niari Province , Louesse River at Mayoko (2°17′23.8″ S, 12°47′31.0″ E) GoogleMaps . — AMNH 258473 View Materials , 1 specimen, Republic of Congo, Niari Province , Leala River (2°13′35.4″ S, 12°56′5.1″ E) GoogleMaps . — AMNH 264169 View Materials , 22 specimens, Republic of Congo, Niari Province , Leala River (2°13′35.4″ S, 12°56′35.1″ E) GoogleMaps . — AMNH 258889 View Materials , 20 specimens, Republic of Congo, Niari Province , Tributary of Mandoro River (2°17′38.6″ S, 12°51′56.8″ E) GoogleMaps AMNH 256454 View Materials , 3 specimens, 1 C&S, Republic of Congo, Niari Province , Lipia River (2°17′31.7″ S, 12°48′29.5″ E) GoogleMaps . — AMNH 264184 View Materials , 12 specimens, Republic of Congo, Niari Province , Tributary of Mandoro River, (2°23′46.6″ S, 12°55′20″ E) GoogleMaps AMNH 264194 View Materials , 11 specimens, Republic of Congo, Niari Province , Tributary of Mandoro River, (2°23′27.5″ S, 12°54′55.7″ E) GoogleMaps .

Enteromius rouxi: AMNH 253939, 1 specimen, Republic of Congo, Nairi Province, Kouilou-Niari River at Loudima (4°06′01.0″ S, 13°03′38.0″ E). — AMNH 253828 View Materials , 1 specimen, Republic of Congo, Loungou River .

Enteromius rubrostigma: AMNH 264335, 4 specimens, 1 C&S, Republic of Congo, Niari Province   GoogleMaps , Loula River (2°26′39.2″ S, 12°58′13.2″ E). — AMNH 253905 View Materials , 1 specimen, Republic of Congo, Lekoumou Province , Passi-Passi River (3°51′58.4″ S, 12°20′47.2″ E) GoogleMaps .

Enteromius stigmatopygus: AMNH 230662, 264 specimens, Chad, Manovo-Gounda National Park , Waula Lagoon.

Enteromius sublineatus: AMNH 256981, 5 specimens, Guinea (9°42′20.2″ S, 10°24′42.9″ E).

Enteromius trispilomimus: AMNH 263487, 1 specimen, Republic of Congo, Kouilou Province   GoogleMaps , Kigongo River (4°33′39.5″ S, 12°06′30.4″ E). — AMNH 254007 View Materials , 1 specimen, Republic of Congo, Lekoumou Province , Passi-Passi River (3°51′58.4″ S, 12°20′47.2″ E) GoogleMaps .

Enteromius walshae: AMNH 266810, 4 specimens, 34.0– 52.1 mm SL, Republic of Congo, Niari Province, Mayoko County, Tributary of Mandoro River (2°18′12.7″ S, 12°58′28.4″ E), G. Walsh et al., 16 October 2013. — AMNH 256505 View Materials , 7 specimens, Republic of Congo, Niari Province , Mayoko County, Bakoulou River at Mayoko (2°17′28.9″ S, 12°47′36.5″ E) GoogleMaps , V. Mamonekene , 3 April 2012 . — AMNH 266809 View Materials , 5 specimens, Republic of Congo, Niari Province , Mayoko County, Mandoro River (2°24′13.9″ S, 12°58′9.4″ E), G. Walsh et al., 12 November 2013 GoogleMaps . — AMNH 266811 View Materials , 9 specimens, Republic of Congo, Niari Province , Mayoko County, Leala River , Tributary of Louesse River (2°13′35.4″ S, 12°56′35.1″ E), G. Walsh et al., 22 October 2013 GoogleMaps . — AMNH 258861 View Materials , 2 specimens, Republic of Congo, Niari Province , Mayoko County, Lekoumoumayoko River, (2°19′37.6″ S, 12°47′34.7″ E), G. Walsh et al., 10 January 2012 GoogleMaps . — AMNH 258829 View Materials , 4 specimens, Republic of Congo, Niari Province , Mayoko County, Lipia River , tributary of Louesse River (2°16′58.2″ S, 12°49′8.0″ E), G. Walsh et al., 10 January 2012 GoogleMaps .

Enteromius viviparus: AMNH 263442, 22 specimens, Mozambique, Mameme River   GoogleMaps (15°52′35.7″ S, 34°1′47.4″ E).

ZSM

Bavarian State Collection of Zoology

V

Royal British Columbia Museum - Herbarium

IO

Instituto de Oceanografia da Universidade de Lisboa