Leberis colombiensis, Kotov, Alexey A. & Fuentes-Reinés, Juan M., 2015

Kotov, Alexey A. & Fuentes-Reinés, Juan M., 2015, A new species of Leberis Smirnov, 1989 (Cladocera: Chydoridae) from Colombia, Zootaxa 3957 (5), pp. 553-566 : 554-564

Leberis colombiensis sp. nov.

( Figs. 1–5 )

Etymology. The new species is named after Colombia, the country where it was discovered.

Type locality. Ciénaga El Covento, Atlántico Department, Colombia (10º 38'N; 74º 55'W). From this locality, 70 parthenogenetic females, four ephippial females, ten juvenile and two adult males were collected in June and October of 2014 by J. M. Fuentes-Reinés.

Type material. Holotype. Parthenogenetic female deposited at the Museo de Colecciones Biológicas de la Universidad del Atlántico, Colombia, UARC 221M.

Allotype. A dissected adult male from type locality, UARC 222M.

Paratypes. 20 undisected females in alcohol, UARC 223M; 11 undissected females in alcohol, UARC 224M; adult male, UARC 226M-230M; 3 females from Laguna Navio Quebrado, 10 females from Ciénaga Grande de Santa Marta, personal collection of Juan M. Fuentes-Reinés.

Description. Parthenogenetic female. Habitus. In lateral view, body ovoid ( Figs. 1 A, 2A–B), maximum height in middle, height/length about 0.8 in both adults and juveniles. Dorsal margin generally uniformly curved, postero-dorsal angle smoothed, postero-ventral angle broadly rounded. Head small, not keeled, rostrum short and blunt, compound eye and ocellus subequal in size, distance from tip of rostrum to ocellus somewhat larger than between ocellus and eye ( Fig. 2 C).

Head shield elongated, length/width ratio about 1.6–1.8; anterior extremity truncated, posterior portion widely rounded, with three closely located major head pores of equal size, with connection between them ( Figs. 1 B–C, 2D–E), post-pore distance about 1.0–1.2 inter-pore distance. Lateral head pores about 1.2–1.4 inter-pore distances from midline, located at level of central or anterior major head pore.

Labrum with a broad, regularly convex labral keel, apex more or less blunt ( Figs. 1 D–E, 2F); in single female a shallow depression presents at anterior margin near apex ( Fig. 1 F). No setulation, teeth etc. on margin of keel.

Valves. Ventral margin with 67–75 setae of different size in different regions of the margin, between them series of small setules. The posteriormost 6–7 setae with sparsely located, pointed, spine-like short setules, followed by a row of spinules, starting marginally, continued along inner margin to the dorsum ( Figs. 1 G, 2G).

Postabdomen ( Figs. 1 H, 3C) elongated, somewhat tapering distally, length/width ratio about 2.4–2.6. Ventral margin almost straight, with no ridges or setules. Preanal and postanal angle well-expressed, distal angle broadly rounded. Preanal margin short, anal margin 1.3 times longer than the former, postanal margin two times longer than preanal margin. Postanal margin provided with 9–11 clusters of denticles, continued on anal margin ( Figs. 3 D–F). On each side of postabdomen, 9–11 lateral fascicles of relatively long setules ( Fig. 3 G). Postabdominal claw ( Figs. 1 H, 3H) regularly curved, somewhat longer than preanal portion of postabdomen, with fine setulation along ventral margin. Basal spine length about 0.3 of claw length, with a row of setules along its dorsal margin, also there are three long setules at claw base.

Antenna I ( Figs. 1 I, 2H) reaching tip of rostrum, with a smooth surface lacking any ridges, or transverse rows of setules. Antenular sensory seta slender, inserted at 1/3 of antennular length from tip, projecting beyond tip. Nine asthetascs, two of them markedly longer than the others, all aesthetascs projected beyond tip of rostrum.

Antenna II short ( Figs. 1 J, 3A), antennular formula: setae 0-0-3/1-1-3; spines 1-0-1/0-0-1. Setae on proximal and next segment of endopod thinner and shorter than apical setae. Spine on first exopod segment robust, shorter than 0.75 of second segment length. Spines on both apical segment of exopod and endopod relatively short, with a hillock near base of each spine ( Fig. 3 B).

Limb I ( Figs. 4 A, 5A–D) with small, ovoid epipodite (removed in Figs. 4 A, 5A). Accessory seta absent. Outer distal lobe ( Figs. 4 A, 5B, ODL) large, bearing only a single bisegmented seta with unilaterally setulated distal segment. Inner distal lobe ( Figs. 5 B, IDL) with several clusters of short setules, two bisegmented setae of different length, armed by short and thick setules distally, and a small sensillum ( Fig. 5 B, incut). Limb corm almost rectangular in lateral view. Endite 3 with three posterior setae subequal in length ( Figs. 4 F, 5C, a–c), and a single anterior seta (1). On endite 2 three bi-segmented setae (d–f), two longer ones (e–f) unequal in length, unilaterally armed by strong setules distally, third seta (d) short. Endite 1 with three setae (g–i). Fascicles of thin setules on inner face of limb, plus bunches of longer and robuster setules at ventral margin of limb ( Fig. 5 D, arrows). Two serrate ejector hooks of similar size. A small projection with a single seta on limb basalmost portion.

Limb II ( Figs. 4 C, 5E) with exopodite small, lacking setae; inner portion of limb with eight scrapers increasing in size distally ( Figs. 5 E, 1–8). Distal armature of gnathobase with four elements, one of them a minute sensillum ( Fig. 3 E, arrow). Filter plate with seven setae, two distalmost setae shorter than others ( Fig. 5 E, arrows).

Limb III ( Figs. 4 D, 5F–H) with ovoid epipodite. Exopodite rectangular, with two lateral setae ( Figs. 4 D, 5F–G, 5–6) and four distal setae (1–4), seta 4 longest. Distal endite (sensu Kotov 1999) sub-rectangular, with three anterior setae ( Figs. 4 D, 5H, 1–3); setae 1 and 2 stout, basalmost seta 3 with long setules distally. A small sensillum between setae 1 and 2, and between setae 2 and 3. On proximal endite, four anterior setae and four soft posterior setae ( Fig. 6 A, a–d), all armed with sparse, fine setules. Distal armature of gnathobase as in L. davidi , filter plate with seven setae ( Fig. 6 B).

Limb IV ( Figs. 4 E, 6C–D) with ovoid epipodite. Exopodite wide, sub-quadrangular, with six setae (1–6), seta 3 longest. Inner limb portion of endopodite with four marginal setae ( Figs. 4 E, 6D, 1–4). Distalmost seta (1) stout, naked; setae 2–4 with inflated proximal segments and slender, unilaterally setulated distal segments, seta 2 largest among the latter. On posterior limb face, three soft setae (a–c). Distal armature of gnathobase with a large sensillum (1), a peculiar brush-shaped seta (2) and two short setae (3–4). Filter plate with five setae.

Limb V ( Figs. 4 F, 6E–F). Epipodite ovoid. Exopodite subovoid, with a single distal ( Figs. 4 F, 6E, 1) and three lateral (2–4) setae. Inner limb portion elongated, with setulated inner margin, with two setulated setae of different length ( Fig. 6 F). Filter plate was not found.

Ephippial female. Habitus similar to that in parthenogenetic female, with a bit elongated body (body height/ body length = 0.7), ephippium slightly additionally pigmented in brown, with a single egg ( Figs. 6 G–H).

Male. Habitus in general similar to female, but maximum height smaller (height/length = 0.7–0.75); posterodorsal angle expressed; postero-ventral angle much more developed as compared with female ( Figs. 1 K, 7A–B). Head larger than in female, rostrum truncated, ocellus in middle of distance between compound eye and tip of rostrum, or more closely located to eye.

Valves with naked setae at postero-ventral angle, followed by a submarginal row of strong spinules of similar size ( Fig. 7 C).

Postabdomen elongated (length/width ratio about 2.55), distal portion of postabdomen more narrow than in female, gonopore opens near base of postabdominal claw ( Figs. 1 L, 7D). Preanal angle projected, postanal angle smoothed, dorso-distal angle widely rounded. Anal margin somewhat longer than preanal margin, postanal margin Postabdomen postanal/ preanal margin About 2.8 About 2.5 About 3.0 About 1.5 1.7–2.0 length

each lateral fascicle on postanal portion Yes No Yes No No

postabdomen distal 1-2 setae stronger

others

Length of basal spine/ length of About 0.4 About 0.2–0.3 About 0.4 About 0.5 About 0.4 postabominal claw

2.8 times longer than preanal margin. Successive series of fine setules on preanal margin ( Fig. 7 E) instead of denticles in female ( Figs. 3 E–F); fascicles of setules on each side of postabdomen, 1–2 distal setules in each group longer and robuster than others ( Fig. 7 F). Postabdominal claws shorter and robuster as compared with females. Basal spine long (length about 0.4 claw length), with large setules along its dorsal margin ( Fig. 7 G).

Antenna I relatively thick, with seven terminal aesthetascs and two lateral aesthetascs, male seta near them, and with a small sensory seta ( Figs. 1 M, 7H).

Trunk limb I with outer distal lobe as in female; inner distal lobe with a strong, U-shaped copulatory hook; two setae as in female but armed by somewhat finer setules, and additional male seta ( Figs. 4 D, 7I, arrow) longer than half of a former seta.

Size. Juvenile females 0.27–0.40 mm; adult parthenogenetic females 0.42–0.50 mm; ephippial females 0.39– 0.50 mm; adult males 0.36–0.42 mm.

Variability. In a single female, an incomplete scraper 4 of limb II was found. In a single female, the spine on the second exopod segment of antenna II was very short, not reaching the half of the next segment.

Differential diagnosis. In the Americas, L. colombiensis sp. nov. could be confused with L. davidi (Richard, 1985) and L. chihuahuensis Elías-Gutiérrez & Velez-Moreno, 2008 . But the former could be easily distinguished from the latter by: (1) smaller post-pore distance in both sexes; (2) in male, postabdomen distal portion symmetrical relative to longitudinal axis, with gonopore region un-inflated, not overhangs base of postabdominal claw; (3) shorter postanal portion of male postabdomen. In addition, L. colombiensis sp. nov. could be differentiated from L. davidi by its smaller maximum size. For other differences see Table 1 .

Distribution and ecology. The species is known to date from Atlántico Department, Magdalena Department and La Guajira Department in Colombia. The type locality, La Ciénaga El Convento, is a small (surface area of 250 ha) lagoon system, with shallow water bodies (depth 0.3–0.8 m) covered by submerged and floating aquatic vegetation, represented by patches of Eichhornia crassipes (Mart.) Solms and Nelumbo nucifera Gaertn. ; temperature varies over the seasons in the range of 27.5–30 ºC; during the sampling pH was 8.6 and conductivity 2,828 µS.cm -1.

Figures

FIGURE 1. Leberis colombiensis sp. nov. from Ciénaga El Convento, Colombia (type locality). A, adult parthenogenetic female, general view. B, head shield. C, dorsal head pores. D – F, labrum and labral keel. G, armature of postero-ventral portion of valve. H, postabdomen. I, antenna I. J, antenna II. K, adult male, lateral view. L, postabdomen. M, antenna I. Scale bars 0.1 mm.

FIGURE 2. Leberis colombiensis sp. nov., parthenogenetic female from Ciénaga El Convento, Colombia (type locality). A – B, general view. C, head. D, head shield. E, major head pores. F, labrum. G, armature of postero-ventral portion of valve. H, antenna I. Scale bars 0.1 mm for A – D; 0.01 mm for E – H.

FIGURE 3. Leberis colombiensis sp. nov., parthenogenetic female from Ciénaga El Convento, Colombia (type locality). A, antenna II. B, distal portions of its branches. C, postabdomen. D, postabdominal anal margin. E – F, armature of postabdominal distal portion; G, lateral fascicles of setules on postabdomen. H, postabdominal claw. Scale bars 0.1 mm for A, C; 0.01 mm for B, D – H.

FIGURE 4. Leberis colombiensis sp. nov., limbs of parthenogenetic female (A, C – F) and male (B) from Ciénaga El Convento, Colombia (type locality). A, limb I. B, distal portion of limb I in male. C, limb II. D, limb III. E, limb IV. F, limb V. Scale bars 0.1 mm.

FIGURE 5. Leberis colombiensis sp. nov., thoracic limbs of parthenogenetic female from Ciénaga El Convento, Colombia (type locality). A, limb I. B, distal portion of limb I. C – D, corm of limb I. E, limb II. F, Limb III. G – H, distal portion of limb III. Scale bars 0.1 mm.

FIGURE 6. Leberis colombiensis sp. nov., female from Ciénaga El Convento, Colombia (type locality). A, limb III, distal portion. B, gnathobase of limb III. C, limb IV. D, inner portion of limb IV. E, limb V. F, inner portion of limb V. G – H, ephippial female. Scale bars 0.1 mm for G – H; 0.01 mm for A – F.

FIGURE 7. Leberis colombiensis sp. nov., adult male from Ciénaga El Convento, Colombia (type locality). A – B, general view. C, postero-ventral portion of valve. D, postabdomen. E, armature of its postanal margin. F, lateral fascicles of setules. G, postabdominal claw. H, antenna I. I, limb I. Scale bars 0.1 mm for A – D; 0.01 mm for E – I.

Tables

TABLE 1. Main morphological differences of Leberis colombiensis sp. nov. from L. davidi, L. chihuahuensis, L. diaphanus and L. aenigmatosus (after Frey 1991, 1998; Sinev et al. 2005; Sinev & Sanoamuang 2011).

Character	L. colombiensis	L. davidi	L. chihuahuensis	L. diaphanous	L. aenigmatosus
Adult female Maximum size of female Number of setae on ventral margin of valve Post-pore/inter-pore distance	0.50 mm 67–75 1.0–1.2	0.69 mm 84–95 1.5–2.0	0.53 mm 51–55 2.3–2.6	0.56 mm 58–67 <1	1.1 mm 101–129 3–4
Anterior margin of labrum Spine on proximal segment of exopod Outer distal lobe of limb I Exopodite III Exopodite IV Finger-like projections on epipodite III-IV	Convex Shorter than second segment With sensillum, without accessory seta Seta 2 and 1 of the same length Seta 2 longer than seta 1 Absent	Wavy Shorter than second segment With sensillum and with accessory seta Setae 1 and 2 of the same length Seta 1 and 2 of same length Present	Convex Longer than second segment Without sensillum, whithout accessory seta Seta 2 longer than seta 1 Seta 2 longer than seta 1 Absent	Convex Longer than second segment Without sensillum, with accessory seta Seta 2 longer than seta 1 Seta 2 longer than seta 1 Absent	Convex Longer than second segment Without sensillum, without accessory seta Seta 2 longer than seta 1 No information Absent
Male Setules in middle of posterior margin longer than in region of postero-venral angle Postabdomen distal portion remarkably asymmetrical relative to longitudinal axis Gonopore region on postabdomen inflated, overhangs base of postabdominal	No No No	Yes Yes Yes	No Yes Yes	Yes Yes No	No No No