Alona kotovi Sinev, 2012, sp. nov.
Creators: name: Sinev, Artem Y.
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Branchiopoda
Diplostraca
Alona
Alona kotovi

description: Alona kotovi sp. nov.   
 Etymology: The species name honors my friend and colleague, prominent Russian cladocerologist Dr. Alexey Alexeevich Kotov.   
 Type locality: forest stream near Bau Chim lake, Cat Tien National Park, Dong Nai Province, Vietnam, N 11°28.787', E 107°22.744'.   
 Type material. Holotype: parthenogenetic female from type location, MGU Ml 113;   
 Paratypes: 3 parthenogenetic females from type location, MGU Ml 114; 6 parthenogenetic females, 2 ephippial females from roadside ditch in Ma Da, Dong Nai National Park, Dong Nai Province, Vietnam 22.10.2009, coll. A. B. Vasilieva, MGU Ml 115.   
Single male from Vietnam, roadside ditch in Ma Da National Park, 22.10.2009, coll. A. B. Vasilieva was studied and dissected afterward, not deposited.  
 Diagnosis. Parthenogenetic female. Alona of moderate size, length up to 0.67 mm. Body oval, moderately high, compressed laterally. Carapace weakly widening posteriorly, maximum height in the third fourth of the body, height/length ratio 0.61–0.65. Posterodorsal and posteroventral angles broadly rounded. Posterior margin convex. Posteroventral angle with 3–5 groups of large setules. Ventral margin with 50–60 setae. Carapace sculpture as weak longitudinal lines.   
Head shield as for genus, rostrum short and rounded, posterior margin as obtuse distal angle. Three major head pores with a narrow connection between them, PP about 0.7–0.9 IP. Lateral head pores minute, located at about 0.3–0.5 IP distance from midline. Labrum of moderate size, labral keel wide, height about 1.5 – 1.7 times width. Anterior margin of keel convex, sometimes with notch near the apex, apex blunt or rounded, posterior margin with two clusters of setae.  
Antennule elongated, length about 3–3.5 width. Antennular seta arising at 2/3 distance from the base. Nine long terminal aesthetascs, two longest about 3/4 length of antennule itself. Antenna with antennal formula, setae 0- 0-3/1-1-3, spines 1-0-1/0-0-1. Seta arising from basal segment of endopodite thin, reaching the end of endopodite. Spine on basal segment of exopodite significantly shorter slightly than middle segment. Spines on apical segments as long as apical segments.  
Five pairs of trunk limbs. Accessory seta of limb I about 3/4 length of ODL seta. IDL of limb I with three setae, seta 1 well-developed, about 1/3 length of ODL seta. Ventral face of limb I with 15–17 long single setules. Exopodite II with long seta, scraping setae not differentiated. Exopodite III with seven setae. Epipodites IV–V without projections. Exopodite V large, elliptical. Filter plate V absent.  
Postabdomen wide, of moderate length, maximum height in the middle of postanal portion. Length about 2.5– 2.6 height. Ventral margin straight. Distal angle broadly rounded. Dorsal margin weakly convex in postanal portion and weakly concave in anal one, distal part about 2.5 times longer than preanal one, postanal portion 2 times longer than anal one. Preanal angle weakly defined, postanal angle not defined. Postanal margin with 10–12 well-developed, single sharp denticles, each with several spinules along anterior margin. Postanal portion with 10– 11 lateral fascicles, posteriormost setae of each fascicle longest, 1.5 times longer than neighboring marginal denticles. Postabdominal claw slender, of moderate length, equal to preanal portion of postabdomen. Basal spine long and slender, about 1/3 of the claw length.  
Antennule elongated, length about 3–3.5 width. Antennular seta arising at 2/3 distance from the base. Nine long terminal aesthetascs, two longest about 3/4 length of antennule itself. Antenna with antennal formula, setae 0- 0-3/1-1-3, spines 1-0-1/0-0-1. Seta arising from basal segment of endopodite thin, reaching the end of endopodite. Spine on basal segment of exopodite significantly shorter slightly than middle segment. Spines on apical segments as long as apical segments.  
 Male. Length 0.49 mm. In lateral view, body low oval, maximum height at the middle of the body, height/ length ratio about 0.55. Postabdomen broad, massive, maximum height at the middle of postanal portion. Length about 2.7 height. Postabdominal claws situated on small protrusion in ventral portion of convex distal margin. The sperm ducts open above the protrusion, posteroventral angle well-defined, posterodorsal angle broadly rounded. Preanal angle weakly defined, postanal angle not defined. Preanal margin almost straight. Clusters of thin setules in place of female marginal denticles. Lateral fascicles of setules same as in female. Postabdominal claw strongly curved, much shorter than in female, length about 2/3 of that of anal margin, with snall spine at the end. Basal spine long, about half length of claw itself. Antennule with 12 long terminal aesthetascs, three longest about 3/4 length of antennule itself. Male seta located at 3/4 distance from the base, about 1/3 length of antennule. Limb I with Ushaped copulatory hook. The IDL has four setae; IDL seta 1 strongly reduced, IDL setae 2 and 3 short and thin, the male seta curved, slightly shorter than seta 2. The copulatory brush seta about 2/3 of IDL seta 2. Ventral face of the limb under the copulatory brush with row of 17 stiff setules.   
 Description. Parthenogenetic female. In lateral view, body oval, moderately high, compressed laterally (Fig. 1 A,D,E). Carapace weakly widening posteriorly, maximum height in the third fourth of the body. Height-length ratio 0.61–0.65 in adults. Dorsal margin convex, posterodorsal and posteroventral angles broadly rounded. Posterior margin convex. Posteroventral angle with 3–5 groups of large setules, with 5–9 setules in each, length of setules in groups increase posteriorly (Fig. 1 G–H). Ventral margin weakly convex, with 50–60 setae (Fig. 1 F). Anterior 17–20 setae long, next 10 setae 2 times shorter short, setae in the posterior part of anterior margin of medium length, gradually decreasing in length posteriorly. Anteroventral angle rounded. Carapace sculpture as weak longitudinal lines.   
 Head relatively small, triangle-round in lateral view. In lateral view rostrum protruding downwards. Ocellus of variable size, in some specimens slightly smaller than eye. Distance from tip of rostrum to ocellus about 1.5 times of that between ocellus and eye.   
 Head shield (Fig. 1 I) with maximum width behind mandibular articulation. Rostrum short and rounded. Posterior margin as obtuse distal angle. Three major head pores with a narrow connection between them (Fig. 1 J). Central pore significantly smaller than two others. PP about 0.7–0.9 IP in adults. Lateral head pores located in small depressions about 0.3–0.5 IP distance from midline, at level between anterior and central major head pore.   
 Labrum of moderate size, without lateral projections (Fig. 1 B–C, K–N). Labral keel wide, height about 1.5–1.7 times width. Anterior margin of keel convex, in Cat Tien specimens with notch near the apex, apex blunt or rounded, posterior margin almost straight, with two-three clusters of setae.   
 Thorax two times longer than abdomen. Dorsal surface of abdominal segments not saddle-shaped.   
 Postabdomen (Fig. 2 A–C) wide, of moderate length, maximum height in the middle of postanal portion. Length about 2.5–2.6 height. Ventral margin straight. Basis of claws bordered from distal margin by clear incision. Distal margin straight, distal angle broadly rounded. Dorsal margin weakly convex in postanal portion and weakly concave in anal one, distal part about 2.5 times longer than preanal one, postanal portion two times longer than anal one. Preanal angle weakly defined, postanal angle not defined. Preanal margin almost straight. Postanal margin with 10–12 well-developed, single sharp denticles, each with several spinules along anterior margin, size of denticle increasing distally. Length of longest denticles slightly more than width of base of postabdominal claw, 2.5–3 times exceeding the width of the denticle base. Anal margin with 4–5 groups of marginal spinules and setules. Postanal portion with 10–11 lateral fascicles, posteriormost setae of each fascicle longest, 1.5 times longer than neighboring marginal denticles. Anal portion with numerous smaller fascicles, spaced irregularly, in two-three rows. Postabdominal claw slender, of moderate length, equal to preanal portion of postabdomen. Basal spine long and slender, about 1/3 of the claw length.   
 Antennule (Fig. 2 D) elongated, narrow, length about 3.5 width, with 4 clusters of short setules at anterior face. Antennular seta thin, of about half length of antennule, arising at 2/3 distance from the base. Nine long terminal aesthetascs, two longest about 3/4 length of antennule itself, all other exceeding half length of antennule. All aesthetascs projecting beyond anterior margin of the head shield.   
 Antenna relatively short (Fig. 2 E). Basal segment robust, with short seta between branches, branches relatively short, all segments cylindrical, subequal in length. Middle segment of exopodite bearing cluster of about 5 long spinules. Seta arising from basal segment of endopodite thin, reaching end of endopodite. Seta arising from middle segment of endopodite of similar size to apical setae. Spine on basal segment of exopodite significantly shorter than middle segment. Spines on apical segments as long as apical segments.   
 Thoracic limbs: five pairs.   
 Thoracic limb I of moderate size (Fig. 3 A–B). Epipodite oval, without process. Accessory seta long, only about 3/4 length of ODL seta, with long setules in distal part. ODL with one seta. IDL with three setae and 3 clusters of short stiff setules. IDL seta 1 well-developed, slender, weakly curved, about 1/3 of ODL setae, setae 2 and 3 with an annulus and dense setules in distal part, seta 3 as long as ODL, seta 2 about 3/4 length of ODl seta. Endite 3 with four setae subequal in length and cluster of 4–5 large spinules. Endite 2 with two long distally setulated setae, one of them 1.3 times longer than to ODL, other slightly shorter than ODL seta, and shorter setulated seta and a short naked seta with small sensillum near its base on anterior face of limb. Endite 1 with two 2-segmented setae, both setulated in distal part, a flattened plumose seta pointed the limb base, and a naked seta shorter than that of endite 2 and a sensillum on anterior face of limb. Ventral face of limb with 15–17 very long setules not organized in clusters. Two ejector hooks, subequal in size. Maxillar process with single seta.   
 Thoracic limb II sub triangular (Fig. 2 F–G). Exopodite elongated, with long slender seta as long as exopodite itself, and a cluster long setules in distal part. Eight scraping spines, spines 6–8 subequal in length, spines 2–5 evenly increasing in length distally, spine 1 significantly longer than spine 2. Size of denticles on basal part of spines evenly decreasing from basal to distal spines. Distal armature of gnathobase with four elements, two lateral are minute, pointed, one of the middle elements broad, robust. Filter plate of seven setae, the posteriormost member two times shorter than middle setae, with long setules.   
 Thoracic limb III (Fig. 3 C–D). Epipodite oval, without any projection. Exopodite subrectangular shaped, with seven setae. Seta 3 longest, setae 6 about 1/3 length of seta 3, other setae very short. Setae 1–5 plumose, seta 6 in distal part armed bilaterally with hard setules, seta 7 naked. Distal endite with 3 setae, two distalmost members scraping, slender, sharp, with long denticles in distal part, one 1.5 times longer than other, short bottle-shaped sensillum located between their bases; basalmost seta short, flattened, bilaterally armed with long setules, small sensillum near its base. Basal endite with 4 plumose setae increasing in size basally. Four pointed soft setae increasing in size basally, a small bottle-shaped sensillum near the distalmost seta. Distal armature of gnathobase with four elements. First one an elongated, narrowing distally sensillum, second strongly geniculated seta, third and fourth-spines with fused bases. Filter plate of seven setae of similar length.   
 Thoracic limb IV (Fig 3 F–G). Pre-epipodite setulated; epipodite oval, without any projection. Exopodite sub quadrangular, with six setae. Seta 1 being longest, setae 2–3 slightly shorter, seta 4–5 of about 2/3 length of seta 1, seta 6 about half length of seta 1. Setae 1–4 flattened, plumose, setae 5–6 thin, naked. Inner portion of limb IV with four setae and retort-shaped sensillum. Scraping seta slender, sharp, three flaming-torch seta of similar shape, decreasing in size basally, with 8–10 long setules each. An elongated sensillum between the bases of middle and basal flaming torch setae. Three soft setae slightly increasing in size basally. Gnathobase with one long twosegmented seta and a small hillock distally. Filter plate of five setae, base of distalmost seta very broad.   
 Thoracic limb V (Fig. 3 H). P re-epipodite setulated; epipodite oval, with any projection. Exopodite large, egg shaped, not divided into lobes, with four plumose setae. Seta 1–3 long, subequal in length, seta 4 very short, more than five times shorter than seta 5. Inner lobe as broad, widening distally lobe, with setulated inner margin. At inner face, two setae densely setulated in distal part, one of them as long as exopodite seta 1, other 2.5 times shorter with a broad-based sensilla-like structures near its base. Filter plate absent.   
 Ephippial female (Fig. 1 O) with body higher than parthenogenetic female, height-length ratio about 0.65. Ephippium of weak yellow-brown color, transparent, with thick longitudinal lines.   
 Male. Body (Fig 1 P) low oval, with maximum height at the middle of the body, height/length ratio about 0.57. Dorsal margin of valves almost straight. Rostrum broader than in female, truncated.   
 Postabdomen (Fig. 2 H) broad, massive, maximum height at the middle of postanal margin. Length about 2.5 height. Ventral margin straight. Postabdominal claws situated on small protrusion in ventral portion of convex distal margin. The sperm ducts open above the protrusion, posteroventral angle well-defined, posterodorsal angles broadly rounded. Dorsal margin weakly convex in postanal portion and weakly concave in anal one. Preanal angle weakly defined; postanal angle not defined. Preanal margin almost straight. Clusters of thin setules in place of female marginal denticles. Lateral fascicles of setules same as in female. Postabdominal claw strongly curved, much shorter than in female, length about 2/3 of that of anal margin. There is a short spine at the end of postabdominal claw. Basal spine long, about half length of claw itself.   
 Antennule (Fig. 2 I) shorter and broader than in female, with 12 long terminal aesthetascs, three longest about 3/ 4 length of antennule itself, all other exceeding half length of antennule. Male seta located at 3/4 length from the base, about 1/3 length of antennule.   
 Thoracic limb I (Fig. 3 I–J) with U-shaped copulatory hook, almost as long as limb itself. The IDL has four setae: IDL seta 1 very short and thin; IDL setae 2 and 3 much thinner and two times shorter than in female; the male seta curved, slightly shorter than seta 2. Copulatory brush seta about 2/3 of IDL seta 2. Ventral face of the limb under the copulatory brush with row of 17 stiff setules. Inner seta of endite 3 much longer and thinner than in female, a cluster of long stiff setules near its base.   
 Size. In single studied females of first juvenile instar, length 0.36 mm, height 0.21 mm; in three females of second juvenile instar, length 0.5–0.52 mm, height 0.28–0.29 mm. In adult females length 0.52–0.67 mm, height 0.31–0.42 mm. Length of single studied adult male was 0.49 mm, height 0.29 mm.   
 Differential diagnosis. Alona kotovi sp. nov. belongs to the quadrangularis -group of Alona s. lat. recently defined as Alona s. str. by Van Damme & Dumont (2008), and has all characteristic features of this group, separating it from other Alona -like species. They include: (1) broad postabdomen with convex postanal margin, armed with well-developed marginal denticles and lateral fascicles of setules; (2) head shield with angular posterior margin and three main head pores; (3) very large, single setules on ventral face of limb I; (4) characteristic shapes of exopodites III–V, and others (for full list see Van Damme & Dumont 2008). A. kotovi sp. nov. differs from A. quadrangularis (O.F. Müller, 1776) by greater number of setules on the ventral face of limb I; from A. kolweizii Van Damme & Dumont, 2008 by greater size, more high body, and by presence of cluster of welldeveloped spines on the middle segment of antennal exopodite; from A. boliviana Sinev & Coronel, 2006 by the shape of the body and postabdomen, by narrow labral keel and by absence of projections on epipodites IV–V; and from Alona yara Sinev & Elmoor-Loureiro 2010 by greater size, by morphology of flaming-torch setae on endopodite IV, and by shape of male postabdomen. Postabdominal claw of male of A. kotovi sp. nov. bears a small spine, which is absent in males of A. quadrangularis and A. yara (males are unknown for A. kolweizii and A. boliviana). Other characters separating species are summarized in Table 1.   
 Ecology. More than forty water bodies in Cat Tien National Park were sampled, including large lakes (Bau Sau and Bau Chim), small lakes and ponds, temporary pools, rivers and streams, and rice fields and ponds in agricultural area outside of the National Park boundaries during April-May 2009 and September-October 2010. A. kotovi sp. nov. was found only in single location in autumn, at the end of wet season. It was found in small forest stream, on clay bottom covered by thin layer of muddy sediment, without leaf litter, together with Nicsmirnovius eximius (Kiser, 1948) and Leydigia ciliata Gauthier, 1939. At the moment of sampling the stream was rather slow, but after each heavy rain such forest streams greatly increase in volume and speed.   
 In Ma Da National Park, A. kotovi sp. nov. also was found in autumn, in similar environment, flow-trough roadside ditch with muddy bottom, together with Nicsmirnovius eximius, Leydigia ciliata, Camptocercus vietnamensis Than, 1980 and Anthalona sanoamuangae Sinev & Kotov 2012. Absence of Alona kotovi sp. nov. in samples from stagnant water bodies suggested its preference by rheophilic conditions.   
 Distribution. So far known from South Vietnam only, but wider distribution is expected.
description: Published as part of Sinev, Artem Y., 2012, Alona kotovi sp. nov., a new species of Aloninae (Cladocera: Anomopoda: Chydoridae) from South Vietnam, pp. 45-54 in Zootaxa 3475 on pages 46-53, DOI: 10.5281/zenodo.209547