Notoalona globulosa ( Daday, 1898 ), 1987

Neretina, Anna N., Kotov, Alexey A. & Damme, Kay Van, 2019, A new case of false “ wide ” distribution for tropical cladocerans: the genus Notoalona Rajapaksa & Fernando, 1987 (Crustacea: Cladocera) in the Old World, Zootaxa 4615 (3), pp. 489-510 : 491-498

Notoalona globulosa ( Daday, 1898)

( Figs. 1–5 )

Alona globulosa Daday, 1898 in Daday 1898: p. 37 –38, figs. 16a–c.

Notoalona globulosa ( Daday, 1898) in Rajapaksa & Fernando 1987a: p. 132 –138, figs. 1–40.

Indialona globulosa ( Daday, 1898) in Michael & Sharma 1988: p. 225 , figs. 78c–f.

Indialona globulosa ( Daday, 1898) in Venkataraman 1992: p. 142 , figs. 6–10.

Notoalona globulosa ( Daday, 1898) in Kotov et al. 2013: p. 28 , figs. 12f–j.

Etymology. Species epithet means rounded, abrupt ( Daday 1898).

Type locality. Swamps near Kalawewa lakes, Sri Lanka ( Daday 1898).

Type material.

Lectotype. A parthenogenetic female marked by circle on slide, DAD II/P-674.

Paralectotypes. 3 females on the same slide with lectotype, DAD II/P-674; 4 females, DAD II/P-674; 3 females, DAD II/P-675; 10 females, DAD II/P-676, few females, DAD II/P-677; II/P-678. Lectotype and paralectotypes were selected by D.G. Frey ( Forró & Frey 1982).

Material studied from South East Asia.

Thailand: 3 parthenogenetic females from a big pond near Sisom village, Tambon Pakhai region, Thong Saen Khan District , Uttaradit Province, coll. 04.04.2003 by A.A. Kotov, S. Lekchan & N. Phukham, AAK 2003-054; 1 parthenogenetic female from a channel near the road, Muang District , Phitsanulok Province, coll. 04.04.2003 by A.A. Kotov, S. Lekchan & N. Phukham, AAK 2003-055; 10 parthenogenetic females from Paddy field, near Phitsanulok, floodplain of the River Nan, Phitsanulok Province, coll. 27.09.1996 by L. Sanoamuang, AAK 2004-050.

Laos: 3 parthenogenetic females from Vientiane Province, coll. by S. Siboualipha, AAK 2012-054; 3 parthenogenetic females from Vientiane Province, coll. by S. Siboualipha, AAK 2012-060.

Redescription. Parthenogenetic female. General. Body subglobular ( Figs. 1A , 2 A–C), without expressed dorsal keel, maximum height anterior to body middle (body height/length ratio about 0.85 for all investigated specimens). In dorsal and anterior view body compressed laterally ( Figs. 2 D–H). In lateral view, dorsal margin uniformly curved, depression between head and rest of body absent, dorsal contour never broken near head pores ( Figs. 1A , 2 A–C). Posterodorsal angle of valve expressed, posterodorsal margin weakly convex or almost straight ( Figs. 1A, E , 2 A–C). A row of fine setules (different in size: alternating short and long setules) at inner face of posteroventral margin. Posteroventral angle broadly rounded, provided with 3–4 clusters of short reinforced setules ( Figs. 1E, F ). Ventral margin convex, covered by setae of different size: setae long in anterior portion, then gradually decreasing in size to the middle of margin and then abruptly becoming longer again, decreasing in size to posterior end ( Figs. 1E, G ). Anteroventral angle rounded ( Figs. 1E, H ). Valve with moderately developed sculpture, consisting of diagonal lines ( Figs. 2 A–E, G–H).

Head small, not keeled, triangular in the lateral view, with convex dorsal margin ( Figs. 1 A–B, 2A–C, 3A–B). Rostrum well-expressed, relatively blunt ( Figs. 2 A–H, 3A–D). Eye significantly larger than ocellus. Distance from tip of rostrum to ocellus slightly greater than distance between ocellus and eye ( Figs. 1 A–B, 2A–C). No major median head pore(s). Two small head pores located on thickening bean-like hills ( Figs. 1C , 2 E–F, 3E–F).

Labrum broadly curved anteriorly with setulated labral plate. Apex of keel rounded with small denticles or notches ( Fig. 1D ).

Thorax relatively long, abdomen short ( Fig. 1A ).

Postabdomen moderately tapered distally in lateral view, postabdomen length/height ratio about 2.6 ( Figs. 1I , 4A , C–D). In dorsal view, postabdomen flat ( Fig. 4B ). Ventral margin almost straight ( Figs. 1I , 4A ). Preanal margin short; length of anal margin almost equal to that of preanal margin, postanal margin about 1.8 times longer than anal margin ( Figs. 1I , 4A ). Preanal and postanal angles well-expressed ( Figs. 1I , 4A ). Basis of claw slightly inflated, bordered from distal margin by a clear incision ( Figs. 1I , 4A , C–D). Postanal part of postabdomen armed with groups of small marginal denticles, anal margin covered by 3 groups of such denticles ( Figs. 1I , 4A , C–D). Marginal denticles in these groups slightly decreasing in size from postanal to anal margin ( Figs. 1I , 4A , C–D). Groups of tiny setules on postanal and anal margins between groups of marginal denticles ( Figs. 1I , 4A , C–D). On postanal margin, the distalmost setule of each group the longest, the groups of setules form a row parallel to dorsal margin of postabdo- men ( Figs. 1I , 4A , C–E). This row continues on the anal margin, and setules in groups of this margin are subequal in length ( Figs. 1I , 4A ).

Postabdominal claw long and narrow (subequal in length to anal margin of postabdomen), and slightly curved ( Figs. 1 I–K, 4A, C–E). External side of claw armed by a row of fine denticles, subequal in thickness and gradually decreasing in length distally ( Figs. 1J , 4A , C–E). Internal side of claw with a row of teeth more robust in the proximal part and decreasing in size distally ( Figs. 1K , 4 B–G). Basal spine short, almost subequal in size to bases of claws ( Figs. 1 I–K, 4A, C–E). A bunch of short fine setules near basal spine ( Figs. 4B, G ) (although in some specimens this bunch was not found probably due to problems with its preservation during dissection, or presence/ absence of this bunch is a kind of variability between individuals).

Antenna I relatively long and narrow (length/diameter at base about 3), fusiform, not reaching tip of rostrum ( Fig. 1L ). Antennular sensory seta slender, longer than antennular body, arising subdistally. All aesthetasc tips project beyond the tip of the rostrum. Two aesthetascs slightly longer than others ( Fig. 1L ).

Antenna II relatively short ( Fig. 1A ). Antennal formula: setae 0-0-3/1-1-3, spines 1-0-1/0-0-1. Coxal part fold- ed, with two sensory setae significantly different in size ( Fig. 1M ). Basal segment robust, weakly setulated with very short spine on anterior surface of segment between branches of antenna II. Branches elongated, subequal in size, all their segments cylindrical, with rows of fine setules. Apical setae long for a chydorid (three times longer than antennal branch), setulated ( Fig. 1M ). Seta arising from basal segment of endopod thin and short (not reaching tip of endopod). Seta from middle endopod segment shorter than apical setae. Spine on basal segment of exopod very short. Spines of both apical segments short, each slightly longer than spine on exopod basal segment ( Fig. 1M ).

Thoracic limbs: five pairs ( Figs. 5 A–I).

Limb I large ( Figs. 5 A–B). Accessory seta was not found. Outer distal lobe conical and relatively large, bearing a small hillock near base and a single long bisegmented seta with distal segment finely setulated ( Fig. 5A ). Inner distal lobe with three bisegmented setae differing in length, distal segments of each seta armed unilaterally by robust denticles ( Figs. 5 A–B). Near the base of smallest IDL seta a sensillum is located, a group of setules on IDL outer face ( Figs. 5 A–B). Limb corm almost rectangular in lateral view, setulated ( Fig. 5A ). Endite 4 with three posterior setae (two of them, seta a and seta b subequal in size and covered by fine setules, seta 3 shorter and covered by more robust setules) and a single anterior seta 1 (feathered by long fine setules) ( Fig. 5A ). Endite 3 with three posterior setae (among them seta d short, setae e and f relatively long, subequal in size) and a single anterior seta 2, represented by a small bisegmented sensillum ( Fig. 5A ). Endite 2 with two posterior seta subequal in length and single short and bifurcated anterior seta 3 ( Fig. 5A ). Endite 1 (maxillar process) with a single, relatively long bisegmented seta ( Fig. 5A ). Two ejector hooks small, setulated, unequal in size ( Fig. 5A ).

Limb II triangular-rounded ( Fig. 5C ). Exopodite ovoid, densely setulated, without setae. Inner portion of limb II with eight scrapers, decreasing in size proximally (towards gnathobase). Deep incision present between endite 2 and endite 1. Gnathobase (= endite 1) portion bordering endite 2 somewhat inflated and setulated ( Fig. 5C ). Distal armature of gnathobase includes four elements: seta 1 represented by a small sensillum, seta 2 relatively long and setae 3 and 4 short and subequal in size. Filter plate with seven setae, increasing in length proximally ( Fig. 5C ).

Limb III ( Figs. 5 D–F) with an ovoid epipodite, exopodite subrectangular, with two bilaterally setulated lateral setae and five distal setae, one of them the longest ( Fig. 5D ). Distal endite (in terms of Kotov 2013) with three anterior setae (1, 2, 3) and a small sensillum near base of seta 1 ( Fig. 5E ). Under light microscope, armature of these setae are not distinguishable. Proximal endite with four soft anterior setae, a single posterior sensillum and four posterior setae. Distal armature of gnathobase with a thick sensillum, two relatively long setae and a very small sensillum ( Fig. 5F ). Filter plate with seven setae, distalmost seta shorter than others ( Fig. 5D ).

Limb IV ( Figs. 5 G–H) with ovoid densely setulated preepipodite and ovoid epipodite supplied by a long fingerlike projection. Exopodite rounded, with three distal and three lateral setae ( Fig. 5G ). Inner distal portion with four anterior setae, among them distalmost seta 1 stout, three other setae with inflated basal segments and long setules; three posterior setae relatively long ( Fig. 5G ). Distal armature of gnathobase with three elements: a thick sensillum and two small reduced setae ( Fig. 5H ). Filter plate with five setae, distalmost seta shorter than others ( Fig. 5G ).

Limb V ( Fig. 5I ) with ovoid densely setulated preepipodite and ovoid epipodite supplied by a finger-like projection. Exopodite ovoid, with three lateral setae, distal seta was not found (similar to the situation described by Van Damme et al. (2013a) in N. pseudomacronyx ). Inner portion of limb with wide, oval inner lobe densely covered by setules ( Fig. 5I ). Two setae unequal in length near base of this lobe. Filter plate was not found, but some protuberances were distinguishable, representing a distal armature of gnathobase ( Fig. 5I ).

Ephippial female, male. No ephippial females and males were found in our material; their descriptions are in Rajapaksa & Fernando (1987a). Size. In our material, adult parthenogenetic females were up to 0.42 mm in length and 0.38 mm in height. Variability. No significant variability was found between investigated South East Asian populations. The shape of the labral apex may be slightly variable due to different number of notches, as this was pointed for other species of Notoalona (e.g. Rajapaksa & Fernando 1987a). Some minor variability could be noted concerning the degree of development of the setules bunch near the postabdominal basal spine, but this feature is on the resolution limit for dissection of a restricted number of specimens from natural populations. This fine feature requires more close investigation, probably, in a monoclonal culture on abundant material.

Differential diagnosis. N. globulosa in the Old World tropics could be confused with N. pseudomacronyx , but it could be reliably distinguished from N. pseudomacronyx by the short postabdominal basal spine (for detailed comparison see Table 1 ).

Taxonomic remarks. Rajapaksa & Fernando (1987a) proposed to distinguish two subspecies of N. globulosa . In their opinion, N. globulosa globulosa is distributed in the tropics of the Old World, including Africa (but see below our analysis of the African populations). Australia according to aforementioned authors is inhabited by an- other subspecies, N. globulosa australiensis Rajapaksa & Fernando, 1987 . The morphological differences between parthenogenetic females of all listed taxa are exclusively fine and mainly related to the armature of the postabdominal claw (see here in Table 1 and in Rajapaksa & Fernando (1987a)), but they may be easily confused under light microscope. At the same time, morphology of ephippial females and males of both subspecies are basically similar (see here in Table 1 and in Rajapaksa & Fernando (1987a)). In our opinion, there is no need to subdivide N. globulosa into two subspecies, although type material of N. globulosa australiensis was not reexamined here and we have to consider this taxon as N. globulosa s.l. In any case, discrimination between populations from tropical Asia and Australia seems problematic based on morphology of parthenogenetic, gamogenetic females and males, therefore genetic methods are urgently needed.

Distribution and ecology. N. globulosa s.l. is known from tropical Asia to Australia, although the number of records (supported by figures of the postabdominal claws) is not large ( Rajapaksa & Fernando 1987a; Michael & Sharma 1988; Venkataraman 1992; Kotov et al. 2013). Due to its small size, N. globulosa could be confused or misidentified with some other chydorids during the rapid routine sample analysis under binocular stereoscopic microscopes. According to our observation and literature ( Daday 1898; Rajapaksa & Fernando 1987a; Michael & Sharma 1988; Venkataraman 1992; Kotov et al. 2013), this taxon is associated with temporary large pools covered by vegetation, wet vicinities of lakes and rivers, but its ecology must be clarified in the future.

Figures

FIGURE 1. Notoalona globulosa (Daday, 1898), parthenogenetic female from a paddy field near Phitsanulok, floodplain of the River Nan, Phitsanulok Province, Thailand, coll. 27.09.1996 by L. Sanoamuang.A, Adult parthenogenetic female, lateral view. B, Head. C, Head shield and dorsal pores. D, Labrum and labral keel. E, Valve. F, Armature of posteroventral portion of valve, inner view. G, Armature of ventral portion of valve. H, Armature of anterior portion of valve. I, Postabdomen. J, Postabdominal claw, outer view. K, Postabdominal claw, inner view. L, Antenna I. M, Antenna II. Scale bars 0.1 mm.

FIGURE 2. Notoalona globulosa (Daday, 1898), parthenogenetic females from a paddy field near Phitsanulok, floodplain of the River Nan, Phitsanulok Province, Thailand, coll. 27.09.1996 by L. Sanoamuang. A–D, Adult parthenogenetic female, lateral view. E–F, Adult parthenogenetic female, dorsal view. G–H, Adult parthenogenetic female, anterodorsal view. Scale bars 0.1 mm.

FIGURE 3. Notoalona globulosa (Daday, 1898), parthenogenetic females from Paddy field near Phitsanulok, floodplain of the River Nan, Phitsanulok Province, Thailand, coll. 27.09.1996 by L. Sanoamuang. A–B, Head, lateral view. C–D, Head, anterodorsal view. E–F, Head pores. Scale bars 0.01 mm for A–E, 0.001 mm for F.

FIGURE 4. Notoalona globulosa (Daday, 1898), parthenogenetic females from a paddy field near Phitsanulok, floodplain of the River Nan, Phitsanulok Province, Thailand, coll. 27.09.1996 by L. Sanoamuang.A–B, Postabdomen. C–D, Distal portion of postabdomen. E–G, Postabdominal claws. Scale bars 0.01 mm.

FIGURE 5. Notoalona globulosa (Daday, 1898), parthenogenetic female from a paddy field near Phitsanulok, floodplain of the River Nan, Phitsanulok Province, Thailand, coll. 27.09.1996 by L. Sanoamuang. A, Limb I. B, Inner distal lobe of limb I. C, Limb II. D, Limb III. E, Distal portion of limb III. F, Gnathobase of limb III. G, Limb IV. H, Gnathobase of limb IV. I, Limb V. Scale bars 0.1 mm.