Anthalona simplex, Van Damme, Sinev & Dumont, 2011
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publication ID |
https://doi.org/ 10.11646/zootaxa.2875.1.1 |
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persistent identifier |
https://treatment.plazi.org/id/0390471D-FFDF-1807-FF22-D76569D1CED1 |
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Felipe |
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scientific name |
Anthalona simplex |
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sp. nov. |
Anthalona simplex n. sp.
( Figs 18–19 View FIGURE 18 View FIGURE 19 ).
Etymology. “simplex” refers to the simple labral keel without the typical denticle, the simple cosmaria, fine setulation of IDL setae of first limb and no strong denticulation of scrapers on second limb. We consider these characters as close to the ancestral form.
Material examined. Holotype. Undissected , parthenogenetic female, mounted in glycerol on glass slide, labelled “ Anthalona simplex n. sp. holotype ”, from stagnant pond next to stream with clay bottom, devoid of aquatic plants, between Lubondo and Kolwezi, Lualaba River Basin, Katanga region, DR-Congo, 06.10.1981, Leg. K. Martens, sample 81.015 (labelled “pond CPA, Zaire-Kolwezi ” in UG Zooplankton Collection).
Paratypes: one slide, with ten complete females, labelled “ Anthalona simplex paratypes ”, type locality. Four dissected females, mounted in glycerol on separate glass slides, labelled “ Anthalona simplex n. sp. paratypes ”. One tube (ethanol/formaldehyde) with eleven females, from type locality. Five adult parthenogenetic females from type locality (paratypes) and three adult parthenogenetic females (additional material) from Mulungwishi stream (10°37’00” S, 26°42’00” E), close to Lulua River, vicinity Lufupa , Katanga Region GoogleMaps , SE of DR-Congo, Leg. K. Martens, 14.10.1981, picked from sample 81.067 at UG Zooplankton Collection. All types of A. simplex n. sp. deposited under accession number RBIN IG 31782 INV 96743-96751 at the Royal Belgian Institute for Natural Sciences , Brussels .
Description of adult. Parthenogenetic female. Habitus ( Figs 18A–C View FIGURE 18 ). Body 0.31–0.38mm, average length 0.33mm (n=7). Brown in colour. Body rather long, 1.7 times as long as high ( Fig. 18C View FIGURE 18 ). Shape oval-rectangular, with posteroventral portion strongly extending posteriorly ( Fig. 18C View FIGURE 18 ). In lateral view, rostrum not reaching beyond ventral carapace margin. Ventral carapace margin straight ( Fig. 18C View FIGURE 18 ). Posteroventral corner round, without notch ( Fig. 18H View FIGURE 18 ). Head. Eye just larger than ocellus ( Figs 18A–B View FIGURE 18 ). Well developed rostrum, rounded. Aesthetascs projecting laterally of rostrum and reach beyond it ( Fig. 18A View FIGURE 18 ). Two main head pores ( Fig. 18D View FIGURE 18 ) of same size, narrowly connected. PP distance one third of IP distance, lateral pores at about 0.7 IP distance from midline and just posterior (maximally half of IP distance) from main pores. Lateral pores with simple sacks, which are not subdivided. These structures one to two times as large as a main pore ( Fig. 18D View FIGURE 18 ).
Carapace. Ornamentation smooth or with faint parallel striation ( Fig 18C View FIGURE 18 ), sometimes faint tubercles. Marginal setae 38–46, strongly differentiated into three groups ( Fig. 18A View FIGURE 18 ). Long anterior group of about seven setae, three times as long as median group of eight shortest setae, posterior group with medium sized setae ( Fig. 18A View FIGURE 18 ). Setae fine with fine setules on posterior side. Setae not strongly decreasing in size towards the posteroventral corner, followed by small spinules not arranged in groups ( Fig. 18H View FIGURE 18 ), of similar size.
Labrum ( Fig. 18E View FIGURE 18 ). Labral keel in lateral view axe-shaped with straight to moderately convex margin. No denticle(s) on labral keel.
First antennae or Antennules ( Fig. 18F View FIGURE 18 ). About 1.5–two times as long as wide, sensory seta implanted half way the antennular corm. Two to three groups of fine setules on margin. Aesthetascs in two size groups. Longest aesthetascs about as long as antennular corm, shortest half as long.
Second antennae ( Fig. 18G View FIGURE 18 ). Basal setae not studied. Anterior spine on basal segment short, conical ( Fig. 18G View FIGURE 18 ). Spinal formula (exo/endo) 001/101, setal formula 113/003. At base of first exopod segment group of three to five long fine spinules, about as long as this segment. First exopod seta on antenna narrow ( Fig. 18G View FIGURE 18 ), not reaching beyond ultimate segment; on external side of second exopod segment, group of four to five long spines ( Fig. 18G View FIGURE 18 ). Spine on first endopod segment very long, reaching half of apical endopod segment; main terminal spines on endo- and exopod well developed and longer than apical segment ( Fig. 18G View FIGURE 18 ). Terminal setae subequal in length, none spiniform.
Postabdomen ( Figs 18I–J View FIGURE 18 ). Relatively widest at postanal margin and with rounded dorso-distal margin. Length moderately convex and tapering distally, distal margin not strongly protruding. Distal embayment shallow, about as deep as claw width at base. Preanal corner well developed, triangular, protruding ( Fig. 18I View FIGURE 18 ). Marginal postanal teeth in six to seven postanal groups of one to three elements each ( Fig. 18M View FIGURE 18 ). Distal teeth simple, closer to anal margin consisting of one triangular small denticle with adjacent smaller element ( Fig. 18M View FIGURE 18 ). Lateral fascicles six groups in postanal portion ( Fig. 18I View FIGURE 18 ) consisting of four (distal) to eight (closer to anal margin) elements in each group, parallel. Distalmost element long and thick, protruding half to two thirds of its length beyond dorsal margin of postabdomen ( Fig. 18K View FIGURE 18 ). Marginal postanal teeth about one third of such a thickened lateral spine. Three to four clusters of smaller marginal teeth and three to four rows of fascicles in anal portion ( Fig. 18J View FIGURE 18 ).
Terminal claw ( Figs 18I–J View FIGURE 18 ). Long and slender, longer than anal margin, straight to moderately curved, implanted with setules along dorsal side, but no strong spine in proximal pecten ( Fig. 18I View FIGURE 18 ). Well developed basal spine, one to 1.5 as long as claw width at base and about one fourth of claw length ( Fig. 18L View FIGURE 18 ). Group of three short basal spinules about one third of basal spine ( Fig. 18L View FIGURE 18 ).
First limb ( Figs 19A–C View FIGURE 19 ). Epipodite round with short projection about half of epipodite body. First endite with one dorsal and two marginal setae, second endite with three setae of which two longer (and subequal in size), third endite with four setae ( Fig. 19A View FIGURE 19 ); anterior elements on en1–2 minute ( Fig. 19A View FIGURE 19 ). ODL with one slender seta, with short fine setules and little longer than largest IDL seta ( Fig. 19B View FIGURE 19 ); IDL with two setae; armature of largest IDL setae long unilateral setulation in distal half, no strong denticles or spines. Accessory seta present near base ODL, about a third of ODL seta ( Fig. 19B View FIGURE 19 ). Five anterior setule groups on limb corm with two long setules in first (dorsal) three groups ( Fig. 19A View FIGURE 19 ). Ventral group consisting of short denticles. Ejector hooks relatively long, subequal; gnathobase ( Fig. 19A View FIGURE 19 ) elongate, with setulated apex.
Second limb ( Figs 19D–F View FIGURE 19 ). Exopodite ( Fig. 19D View FIGURE 19 ) oval round, lacking a seta. Short setules on apex; endites with eight scrapers gradually decreasing in size towards gnathobase, sixth and eighth scraper shortest ( Fig. 19D View FIGURE 19 ). First four scrapers relatively slender, finely setulated and decreasing in size towards gnathobase, following four thicker; no scrapers with few strong teeth ( Fig. 19E View FIGURE 19 ) and third scraper longer than fourth; gnathobasic ‘brush’ elongate, implanted with short setules ( Fig. 19D View FIGURE 19 ). Gnathobase with a sensillum and three modified elements, of which first a short seta, second a plump seta with small denticles in distal half and third a short seta; filter comb ( Fig 19D View FIGURE 19 ) with seven setae of which first two shorter and third intermediate. First with setules implanted around its distal half ( Fig. 19F View FIGURE 19 ).
Third limb ( Figs 19G–I View FIGURE 19 ). Pre-epipodite round, epipodite round; exopodite ( Fig 19I View FIGURE 19 ) with quadrangular corm and six large setae in 2+4 arrangement; first exopodite seta one fifth longer than second, both relatively long; third exopodite seta less than two times of fifth exopodite seta, fourth seta twice as long as sixth seta, latter seta half the size of fifth ( Figs 19G–I View FIGURE 19 ); all these setae plumose, except for fifth and sixth ( Fig. 19H View FIGURE 19 ); fifth seta plumose in distal portion only and sixth shortly plumose in distal half. External endite ( Fig. 19J View FIGURE 19 ) with three setae (1’–3’) of which first two long, with long setules in distal half and with minute element in between, third (3’) shorter and with long setules; four well developed plumose setae on inner side (1”–4”) of same length; one naked element and four small naked setae on internal endite ( Fig. 19K View FIGURE 19 ) preceding gnathobase; the latter with a bottle-shaped sensillum and large bent plumose seta with two naked elements at its base ( Fig. 19J View FIGURE 19 ). Filter comb with seven setae (not shown).
Fourth limb ( Figs 19M–O View FIGURE 19 ). Pre-epipodite oval, epipodite oval-round with short projection not reaching half of exopodite ( Fig. 19M View FIGURE 19 ). Exopodite round, implanted with rows of minute denticles on inner side and with six marginal plumose setae; first three exopodite setae long and unequal, third is longer by one fourth of two previous setae; fourth shorter by one third of preceding seta; fifth and sixth setae narrow and shorter by one third to half of fourth seta ( Fig. 19N View FIGURE 19 ). Both these setae (5–6) of similar size. Endite ( Fig. 19O View FIGURE 19 ) with marginal row of four setae, first with distal short armature and longer than flaming torch setae; three ft setae plump with thick base, decreasing in size towards gnathobase, and one marginal naked sensillum, with bent apex; gnathobase with one long setae, bent over endite and reduced naked element; on inner side, three long plumose setae (1”–3”) gradually increasing in size towards gnathobase and a filter comb with five slender setae of similar length of endite seta 3” ( Fig. 19O View FIGURE 19 ).
Fifth limb ( Figs 19P–Q View FIGURE 19 ). Pre-epipodite round, with long setules; epipodite oval with short projection, not reaching half way exopodite. Exopodite ( Fig. 19P View FIGURE 19 ) shape broadly oval, about two times as long as wide, with straight to slightly convex, expanded setulated margin between setae three and four. Four exopodite setae, first (dorsal) two longest, oriented dorsally, about two times as long as exopodite width; third shorter by one fourth of setae (1’–2’) of which first very long, bent over inner lobe and twice as long; second endite seta about half size of first (1’). Gnathobase with one setulated round hillock and small naked projection ( Fig. 19Q View FIGURE 19 ), no filter comb.
Adult male and ephippial female unknown.
Differential diagnosis. Anthalona simplex n. sp. is a relatively small species (~ 0.33mm), with long body in comparison to other species (1.7 times body height). Differs from all other Anthalona in several characters. Structures on the second antenna ( Fig. 18G View FIGURE 18 ): A. simplex n. sp. has a long endopod spine, up to half of third endopod segment and long basal spinules on antennal exopod. On the carapace, A. simplex has an anterior group of long setae ( Fig. 18A View FIGURE 18 ). The postabdomen of A. simplex has a long terminal claw (1.5 times anal margin) and a fine basal spine ( Fig. 18 View FIGURE 18 ), marginal teeth short and longest lateral spines reach beyond them by a third. Labral keel lacks a denticle. On limbs, IDL setae on P1 and denticulation of scrapers on P2 not developed and all epipodite projections short ( Fig. 19 View FIGURE 19 ). For additional characters, see Table 1.
Distribution and ecology. South East of DR Congo, likely an endemic of the Congo Basin. In littoral-benthic environment, on clay substrate, found in stagnant pool and small stream. Sympatric with Anthalona simplex n. sp., we found Alona kolwezii Van Damme & Dumont, 2008 , Macrothrix sp. , Paralona cf. pigra (Sars, 1862) Alona cf. affinis and Anthalona harti n. sp. See also Van Damme & Dumont (2008a).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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