Anthalona verrucosa verrucosa ( Sars, 1901 ), verrucosa (Sars, 1901
DAMME, KAY VAN, SINEV, ARTEM YU & DUMONT, HENRI J., 2011, Separation of Anthalona gen. n. from Alona Baird, 1843 (Branchiopoda: Cladocera: Anomopoda): morphology and evolution of scraping stenothermic alonines, Zootaxa 2875 (1), pp. 1-64: 41-48
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|Anthalona verrucosa verrucosa ( Sars, 1901 )|
( Figs 20–23)
Alona verrucosa Sars, 1901 sensu Sars (1901) , Paggi (1975), Sinev & Hollwedel (2002).
nec Alona verrucosa Lutz, 1879 (see Johnson 1956b)
nec Alona verrucosa sensu Johnson (1956a) ; Jenkin (1934); Rey & St-Jean (1968); Dumont et al. (1981); Alonso (1996)
Material examined. Lectotype. Single parthenogenetic female, Zool. Mus. Oslo, Accession number F12338 View Materials a, Collection G.O. Sars, São Paulo, Brazil.
Paralectotypes. Three adult parthenogenetic females, Zool. Mus. Oslo, Accession number F12337 View Materials , one adult parthenogenetic female, Accession number F12338 View Materials b, Coll. G.O. Sars, from vicinity of São Paulo, Brazil .
Additional material. Five adult parthenogenetic females, one ephippial and one male from dune pool near Atins in the Lençóis Maranhenses, Brazil, 16.VIII.1996, Leg. K. Van Damme (S3A in Van Damme & Dumont 2010); Numerous females, raised from dried mud from dune pools in the Lençóis Maranhenses, Brazil (S2cult in Van Damme & Dumont 2010); Material of the Lençóis deposited under RBIN IG 31782 INV 96752 View Materials -96756. Two adult parthenogenetic females from Fray Bartelomeo de las Casas, Guatemala, 08.III.2006, Leg. H.J. Dumont, RBIN IG 31782 INV 96759 View Materials -96761.
Type locality. Vicinity of São Paulo, Brazil ( Sars, 1901).
Redescription. Adult parthenogenetic female. Habitus ( Figs 20A–C, 21B). Medium sized animals, 0.3–0.36 mm, average length 0.34mm (n=10) for population from Lençóis ( Sars (1901) measured 0.36mm). Body length 1.5 times height. Transparent in life, after fixation more yellowish. Body shape variable (description of body Lençóis specimens). Dorsum moderately convex, highest point near middle; posterior margin angular, with expanded lower portion ( Fig.20C, arrow). The posterior margin forms an angle of about 21 degrees posterior from an imaginary ventro-dorsal axis through the posterodorsal corner of the valves. Maximal ventral extent of rostral tip, about ventral maximum of carapace margin or less ( Fig. 20C). Ventral carapace margin straight. Posteroventral corner round, without notch ( Fig. 20H).
Head. Ocellus smaller than eye (diameter of eye is 1.3 times that of ocellus) ( Fig. 20A). Head shield with well interpore distance short, one to two times the size of diameter of one main pore. PP distance short, mean about half of IP distance, lateral pores at 1.5–two times IP distance from midline and situated posterior to main pores, at a distance of two to three IP from the posterior pore. This distance may vary strongly within a population ( Figs 2A–E) but is mostly large, with a mean of 2.5 times the IP distance. The main pores may be situated at a triangular posterior extension of the head shield ( Fig. 2B). Sacks under small pores with diameter about 1.5 times that of a main pore. These sacks always eight-shaped ( Fig. 20D).
Carapace ( Figs 20B–C, 21A). Smooth ( Fig. 21A) or with verrucae, both forms may occur in single population. Verrucae may be faint to strongly pronounced. Marginal setae 35–45, differentiated into three groups, anterior and median group short, posterior group twice as long. Posterior group with up to 14 setae well distinguished, these setae spaced further from each other than those in median and anterior group and three times as long as setae of median group ( Fig. 20H). Setae not strongly decreasing in size towards the posteroventral corner but ending abruptly ( Fig. 20H). These setules of similar size, reaching beyond carapace margin in posteroventral corner and continuing in a posterior row of fine long setules ( Fig. 20H).
Labrum ( Figs 20E, 21B). Labral keel as for genus and with straight to moderately convex margin, sometimes wavy. One, sometimes two, proximal denticles on labral keel ( Figs 20E, 21B).
First antennae or Antennules ( Fig. 20F). About three times as long as wide, sensory seta implanted at one third of antennular corm. Three to four groups of short denticles on margin (best seen in SEM Fig. 21B). Longest aesthetascs about half of antennular corm, shortest half as long ( Fig. 20F).
Second antennae ( Fig. 20G). Anterior spine on basal segment short, conical. Spinal formula as for genus. At base of first exopod segment, a group of short, modified spinules ( Fig. 21B, arrow). First exopod seta on antenna narrow ( Fig. 20G), reaching beyond ultimate exopod segment; second exopod seta 1.5 times as long as previous; on external side of second exopod segment, three to four strong spines ( Fig. 20G). True spine on first endopod segment reaching end of second segment or just beyond; main terminal spines on endo- and exopod well developed, each as long as their apical segment ( Fig. 20G). Terminal setae on antennal exopod of similar morphology as for endopod and with long setules ( Fig. 20G).
Postabdomen ( Figs 20I–J). Relatively widest at preanal angle, and with rounded dorso-distal margin, between two and 2.5 times as long as wide. Ventral margin shorter than anal and postanal margin together. Postanal and anal margins shorter than preanal margin. Anal margin straight to slightly concave, postanal margin stronger curved, convex. Distal margin protruding, distal embayment (dorsal to basal claw) maximally as deep as claw width at base. Preanal corner ( Fig. 20I) not protruding beyond maximal dorsal point of postanal margin (neither postanal margin or preanal corner reach beyond each other dorsally). Marginal postanal elements arranged in six to seven groups ( Fig. 20I). Each distal tooth with one to two adjacent smaller elements on anterior side, not merged. Lateral fascicles six groups in postanal portion, consisting of six to eight elements in each group, parallel to each other. Distalmost lateral element long, thick and spiniform, protruding for half of its length beyond dorsal margin of postabdomen. Distalmost lateral elements in postanal portion do not reach beyond marginal denticles. Smaller elements per fascicle at least half of the distalmost spine in each group. Three to four clusters of long marginal elements, and three to four fascicles in anal portion.
Terminal claw ( Figs 20I, 20L). As long as anal margin, moderately curved, implanted with setules along dorsal side. Proximal pecten ending in long spine about width of claw at this point and at about half of claw length ( Fig. 20I). Basal spine 1.5 to two times claw width and one fourth to one fifth of claw length. Group of three to four long basal spinules, over half of basal spine length ( Fig. 20L).
First maxilla ( Fig. 22A) as for genus.
Five pairs of limbs. First limb ( Figs 22B–D). Epipodite round with long projection, reaching beyond limb corm ( Fig. 22B). First to third endites as for genus. Anterior elements strongly reduced ( Fig. 22C). Inner and outer distal lobes ( Fig. 22D); ODL with one slender seta, as long as largest IDL seta and with short fine setules in distal half ( Fig. 22D); two setae in IDL, modified. On largest IDL seta, one large spine followed by reduced distal part; spine in longest IDL seta is as long or just longer than distal part beyond spine. On shortest IDL seta ( Fig. 22D), two long spines of similar length, basal spine about as long as distal part of this seta. Accessory seta present, half of IDL seta (not shown). Four to five anterior setule groups with two to three setules in each group ( Fig. 22B), decreasing in size ventrally. Ejector hooks unequal and gnathobase triangular with setulated apex ( Fig. 22B).
Second limb ( Figs 22E–F). Exopodite ( Fig. 22E, ex) oval-round, with short seta, not reaching beyond exopodite apex; tuft of hairs on exopodite apex; endites with eight scrapers gradually decreasing in size towards gnathobase, eight scraper shortest ( Fig. 22E). First two scrapers relatively slender and finely setulated, about twice the size of the third scraper. Third stouter and shorter than two and four, with stronger denticles than scrapers one to five. Scrapers four and five similar, with fine denticles, scraper six ( Fig. 22F) modified with 10–11 thick teeth (in paralectotypes, eight teeth); final two scrapers decreasing in size towards gnathobase, scraper eight thickest, this scraper half the size of sixth. Gnathobasic ‘brush’ short and round, implanted with short denticles. Gnathobase as for genus; filter comb ( Figs 22E) with seven setae of which only the first two shorter. First two setae brushlike, with fine setules.
Third limb ( Figs 22G–I). Pre-epipodite round, epipodite round with long projection; exopodite ( Fig. 22G) as for genus, with six setae; first exopodite seta twice as long as second; third exopodite seta longer by about a third of fifth exopodite seta ( Fig. 22H), fourth seta just shorter than fifth seta and twice as long as sixth seta ( Fig. 22H). Endite ( Fig. 22I) as for genus; strongly developed denticles in setae 1’–2’, long setae in internal endite preceding gnathobase and filter comb setae about twice as long as last seta on inner side (4”) ( Fig. 22I).
Fourth limb ( Figs 22J–L). Epipodite oval with long projection reaching just beyond exopodite. Exopodite ( Fig. 22J) with six marginal plumose setae; first three exopodite setae longer, third one the longest of the three (one third longer than second seta), fourth maximally half as long as preceding seta ( Fig. 22J); fifth and sixth setae narrow. Sixth same length as fourth, fifth just longer than its adjacent setae ( Fig. 22K). Endite ( Fig. 22L) as for genus.
Fifth limb ( Figs 22M–N). Pre-epipodite oval and implanted with long setules; epipodite oval with long projection reaching beyond half of exopodite corm but not beyond margin. Exopodite ( Fig. 22M) shape broadly oval, about two times as long as wide, with concave expanded margin between setae three and four; four exopodite setae, of limb ( Fig. 22N) with broad oval inner lobe and long apical setules; two endite setae (1’–2’) of which first longer; this seta not reaching apex of inner lobe; second endite seta shorter by a third. Gnathobase as for genus.
Adult male ( Figs 23A–C). Size 0.27–0.3mm. (n=4), body 1.95 as long as high. Body not widening posteriorly ( Fig. 23A), dorsum rather parallel to ventral margin. Postabdomen ( Fig. 23B) about 2.5 times as long as wide, with preanal projection (preanal angle) about two times as long as wide (not strongly projecting). Distalmost spine in each lateral fascicle on postabdomen long and reaching beyond dorsal margin of postabdomen ( Fig. 23B). Terminal claw thick and short (shorter than anal margin) with basal spine about as long as claw width at base. Gonopores opening ventrally, adjacent to basal claw and in subterminal indent. First limb ( Fig. 23C) with IDL bearing three setae ( Fig. 23C), of which two modified in distal portion, though less as in females. Third IDL seta naked and as long as two modified setae ( Fig. 14E). ODL seta longer than IDL setae. Copulatory hook ( Fig. 23C) strongly curved and with long terminal part, in inner side of “elbow” with narrow base, more V- than U-shaped.
Ephippial female and ephippium. Ephippial female larger than parthenogenetic female (up to 0.58mm), ephippium light orange brown, never dark brown or black.
Paralectotypes of Anthalona verrucosa ( Sars, 1901) . Redescription above is mainly based on populations from the Lençóis Maranhenses, Brazil. Type material differs in a few details. Sars (1901) did not designate a holotype or paratypes. In 1985, Valdivia-Villar selected several females, which we studied as well. We are, however not sure that these correspond to the animals Sars’ (1901) had before him, because they differ in habitus from the latter. All (para) lectotypes were in a bad state and must have dried out completely in the past, so only limited information could be retrieved. Habitus of (para) lectotypes without verrucae, size 0.375mm ( Fig. 23D) (different from Sars’ (1901) description, which was with verrucae and smaller?!).
Head with rostrum relatively long and curved inwards. Distance between main head pores about four times diameter of one main pore ( Fig. 23I). Lateral pores not far from posterior main pore, their sizes about two times main pore diameter ( Fig. 23I).
Labrum ( Fig. 23G) with convex margin and single tooth, directed forward. First antennae not reaching rostral tip.
Second antenna ( Fig. 23H) with unmodified terminal setae; formula as for genus. Spines on first and second exopod segment quite robust and thick (three or four on each segment). First seta on endopod not reaching apex of third segment, first endopod spine as long as or just longer than second segment. Terminal spines 1.2 times length of apical segments.
Postabdomen ( Figs 23E–F) with anal and postanal margin of similar lengths and typical S-shape, about two times as long as wide.
Terminal claw ( Figs 23E–F) just longer (1.3 times) than anal margin, basal spine on terminal claw about 1.2 times as long as claw width, with basal spinules reaching up to half length of basal spine. Six postanal marginal teeth, longer than wide, distalmost merged with smaller denticles. Lateral fascicles (largest spine per group) reaching tip of marginal denticles or just beyond.
Five limb pairs, epipodites with long fingerlike projections (longer than epipodite itself). First limb with modified IDL setae ( Fig. 23J); basal spine in longest IDL seta as long as or longer than apical part of seta beyond it; shortest IDL seta with basal spine shorter than apical part. Basal spines of both IDL setae are relatively narrow, not markedly thick.
Second limb ( Figs 23K–L) with exopodite with short seta, not reaching over the apex. Eight scrapers ( Fig. 23K) of which third and sixth with stronger teeth. Sixth scraper ( Fig. 23L) with eight to nine teeth. Third to fifth limbs not studied.
Differential diagnosis. Anthalona verrucosa ( Sars, 1901) forms a close group of siblings, on which the final word has yet to be written—its full diversity in South America is no doubt higher than presented here. See also Sinev & Hollwedel (2002) for redescription. A. verrucosa has a typical single denticle (or two) on the labral keel. The species is relatively small (0.34–0.36mm on average). Valve setae with a posterior group are relatively long and widely spaced. Postabdomen with lateral fascicles not (or rarely) reaching beyond the marginal teeth; basal spinules on terminal claw half of basal spine or longer. Major pores very variable, at some distance from the lateral pores in the Lençóis populations (not in the types, this character is variable, see Fig. 2). Body shape may differ, in the Lençóis with an expanded posteroventral portion. On antennae, terminal (swimming) setae are normal, unmod- tinguish two subspecies. A. verrucosa verrucosa ( Sars, 1901) has stronger modified spines on IDL of the first limb (distal part of these setae is not much longer than the large basal spine) than A. verrucosa pectinata ( Elías-Gutiérrez & Suárez-Morales, 1999) .
Distribution and ecology. Distribution of A. verrucosa will have to be re-evaluated in the future; this species is quite common and widespread in the Neotropics (e.g., Sars 1901, Paggi 1975, Sinev & Hollwedel 2002). Tolerates lower acidities but prefers neutral to basic ( Van Damme & Dumont 2010). In our cultures, temperatures of 20°C and below resulted in unhealthy populations, low numbers and with deformations due to bad moulting. The most successful populations, with largest numbers, were obtained at temperatures between 25–30°C. Slow swimmer, feeds on detritus and scrapes off substrate.
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Anthalona verrucosa verrucosa ( Sars, 1901 )
|DAMME, KAY VAN, SINEV, ARTEM YU & DUMONT, HENRI J. 2011|
Biapertura pseudoverrucosa verrucosa ( Sars, 1901 )
|sensu Smirnov 1971|
Biapertura pseudoverrucosa pseudoverrucosa Smirnov, 1971
|pseudoverrucosa (Smirnov 1971|
Alona verrucosa sensu
|Sars, 1901 sensu Sars 1901|