Disparalona (L.) hamata (Birge, 1879)
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publication ID |
https://doi.org/ 10.11646/zootaxa.4567.2.7 |
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publication LSID |
lsid:zoobank.org:pub:AE5B47FC-CE68-4C47-A580-8B93E2D7D410 |
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DOI |
https://doi.org/10.5281/zenodo.5933892 |
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persistent identifier |
https://treatment.plazi.org/id/9B3A3E2C-FE39-6A04-FF39-FDDCFE8BFF48 |
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treatment provided by |
Plazi |
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scientific name |
Disparalona (L.) hamata (Birge, 1879) |
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Disparalona (L.) hamata (Birge, 1879) View in CoL
( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )
Material examined. 15 parthenogenetic females, 8 ephippial females, 8 males from a sole sample AAK 2008-147. Description of bromeliad population. Parthenogenetic female. General. In lateral view, body oval (body height/ length ratio about 0.58 in all investigated females), maximum height at the middle of body ( Fig. 1A View FIGURE 1 ). Body compressed laterally, lacking dorsal keel and lateral processes on valves ( Figs. 1A View FIGURE 1 , C–D, 2A). Dorsal margin broadly curved, depression between head and rest of body absent ( Fig. 1A View FIGURE 1 ). Posterodorsal and posteroventral angles rounded, posterior margin convex ( Fig. 1A View FIGURE 1 ). Surface of valves and head covered by numerous short sometimes wavy lines ( Figs. 2 View FIGURE 2 A–C). Anterior and posterior portions of valves with long prominent parallel lines ( Figs. 1A View FIGURE 1 , C–D, 2A).
Head small, triangular, with relatively long rostrum ( Figs. 1A View FIGURE 1 , 2 View FIGURE 2 A–B). Compound eye larger than ocellus, distance between centre of eye and ocellus almost in two times shorter than distance between centre of ocellus and tip of rostrum ( Fig. 1A View FIGURE 1 ). Number and position of head pores are typical for subfamily Chydorinae : two minute pores located between two major head pores asymmetrically to midline of body (closer to anterior major head pore than to posterior one) ( Figs. 1C, E View FIGURE 1 ).
Labrum large. Labral keel short, triangular ( Figs. 1A, F View FIGURE 1 ). Its anterior margin is almost straight, distal angle is acute.
Valve broadly ovoid ( Figs. 1A, G View FIGURE 1 , 2A View FIGURE 2 ), with a row of numerous fine setulae on posterior margin ( Fig. 1H View FIGURE 1 ) and long setae on ventral ( Fig. 1I View FIGURE 1 ) and anteroventral margins.
Thorax relatively long, abdomen short ( Fig. 1A View FIGURE 1 ).
Postabdomen subrectangular (postabdomen length/height ratio about 2.8) ( Figs. 1A, J View FIGURE 1 , 2A, D View FIGURE 2 ). Ventral margin almost straight, preanal and anal margins equal in length, postanal margin two times longer than preanal and anal margins and parallel to ventral margin ( Figs. 1A, J View FIGURE 1 , 2A, D View FIGURE 2 ). Preanal and postanal angles expressed. Distal angle of postabdomen straight ( Figs. 1A, J View FIGURE 1 , 2A View FIGURE 2 , D–E). Each side of postanal portion with a row of thin and long postanal composite teeth, increasing in size distally. Lateral surfaces of postanal and anal portion covered by bunches of fine setulae. Transverse rows of fine setulae located on ventral margin of postabdomen.
Postabdominal claw long (subequal in length to anal margin), slightly curved ( Figs. 1J View FIGURE 1 , 2A View FIGURE 2 , D–F). Dorsal edge of claw armed with a row of fine spinulae decreasing in size distally. Two basal spines located at claw base ( Fig. 1J View FIGURE 1 ). Distal basal spine longer than proximal one.
Postabdominal seta relatively long, almost two times longer than preanal margin ( Fig. 1A View FIGURE 1 ).
Antenna I cylindrical, not reaching tip of rostrum ( Figs. 1K View FIGURE 1 , 2B, G View FIGURE 2 ). Antennular sensory seta slender, subequal in length to antennular body. Nine aesthetascs, subequal in size.
Antenna II relatively short ( Fig. 1L View FIGURE 1 ). Antennal formula: setae 0–0–3/1–1–3, spines 1–0–1/0–0–1. Basal segment covered by transverse rows of setulae, with a small spine between exopod and endopod branches. Antennal branches subequal in length, all their segments cylindrical, covered by transverse rows of fine setulae. Apical setae long. Seta arising from proximal endopod segment thin and relatively long (subequal in length to endopod branch with apical spine). Seta of the middle endopod segment long, reaching tips of apical setae. Spine of proximal exopod segment short (reach 1/4 portion of the middle exopod segment length). Spines of both apical segments long. Endopod apical spine longer than exopod one.
Thoracic limbs: five pairs ( Figs. 3 View FIGURE 3 A–G).
Limb I large ( Fig. 3A View FIGURE 3 ). ODL conical, with two setae: long seta and short one. IDL with three setae, two of them slender, third seta represented by thick, curved hook. In lateral view, limb corm almost rectangular. Endite 4 with three soft posterior setae (a–c) subequal in size and a stiff anterior seta 1. Endite 3 with three posterior setae (a short posterior seta “d”, especially long seta “e”, shorter seta “f”) and a stiff anterior seta 2. Endite 2 with three posterior long setae (g–i), short seta “j” (not shown on the figure), and anterior stiff seta 3. Rows of long and robust setulae located between seta 2 and seta 3. Endite 1 with a short seta not shown. Two slender long ejector hooks unequal in length.
Limb II triangular ( Fig. 3B View FIGURE 3 ). Exopodite ovoid, with a long seta. Inner portions of limb with eight scrapers. A series of small projections posteriorly to distal setae, and a long sensillum between scraper 3 and 4. Distal side of gnathobase (= endite 1 sensu Kotov (2013)) with a row of fine long setulae. Distal armature of gnathobase with four elements, one of them represented by minute sensillum. Filter plates with eight setae.
Limb III with ovoid epipodite ( Fig. 3C View FIGURE 3 ). Exopodite almost rectangular, with three lateral seta and four distal setae differing in size and armature. Distal endite (in terms of Kotov (2013)) with three anterior setae ( Fig. 3C View FIGURE 3 : 1, 2, 3). Proximal endite with four small anterior setae. Six (a–f) soft setae on posterior surface of limb setae ( Fig. 3C View FIGURE 3 ). Distal armature of gnathobase with four elements: thick bottle-shaped sensillum and three small setae ( Fig. 3D View FIGURE 3 ). Filter plate with eight setae.
Limb IV bears seven setae of different size and armature ( Fig. 3E View FIGURE 3 ). Inner distal portion of limb IV with four setae (1–4) ( Fig. 3F View FIGURE 3 ). Four soft setae (a–d) located on posterior surface of limb IV ( Fig. 3E View FIGURE 3 ). Distal armature of gnathobase with four elements: three small sensillae and a long bisegmented seta ( Fig. 3F View FIGURE 3 ). Filter plate with six setae.
Limb V with ovoid preepipodite and epipodite ( Fig. 3G View FIGURE 3 ). Exopodite large, oval, with a single short distal seta and three long lateral setae. Inner limb portion represented by oval flat lobe with setulated margin. Near this lobe located two setae (1–2). Filter plate with four long setae.
Ephippial female. Shape of body of ephippial female ( Fig. 1B View FIGURE 1 ) almost identical to parthenogenetic female ( Fig. 1A View FIGURE 1 ). Ephippium dark brownish, not bordered via demarcation line from the rest of body. A single large egg in the ephippium.
Adult male. General. Body oval, elongated (height/length ratio about 0.50) ( Figs. 4 View FIGURE 4 A–B). Maximum height almost at the middle of body. Dorsal margin convex, posterodorsal angle expressed, posteroventral angle broadly rounded. Ventral margin straight ( Figs. 4 View FIGURE 4 A–B).
Head elongated ( Figs. 4 View FIGURE 4 A–B), similar with females.
Labrum with triangular labral keel ( Fig. 4C View FIGURE 4 ).
Postabdomen long, typically narrowing distally ( Figs. 4D, G View FIGURE 4 ). Postabdomen length/height ratio about 3.7 ( Fig. 4G View FIGURE 4 ). Ventral and preanal margins straight. Anal and postanal margins slightly concave. Postanal two times longer than preanal and anal margins. Postanal and preanal angles smooth. Distal angle rounded. Postanal margin armed by bunches of setulae. Postanal and anal lateral surfaces covered by bunches of fine setulae. Gonopores open near bases of claws ( Fig. 4G View FIGURE 4 ).
Postabdominal claw almost straight, with two basal spines unequal in length ( Figs. 4 View FIGURE 4 D–F) or only with single basal spine ( Figs. 4 View FIGURE 4 G–H). In the last case it seems that the proximalmost spine is reduced.
Postabdominal seta long ( Fig. 4A View FIGURE 4 ).
Antenna I cylindrical, with nine aesthetascs ( Fig. 4I View FIGURE 4 ). Male seta thick, located near sensory seta.
Antenna II similar to females ( Fig. 4J View FIGURE 4 ), antennal formula: setae 0–0–3/1–1–3, spines 1–0–1/0–0–1.
Limb I with prominent copulatory U-shaped hook ( Fig. 4K View FIGURE 4 ). Copulatory brush seta short, slender. IDL with four setae. Among them two setae slender, one seta represented by massive hook. Their armature similar with parthenogenetic females. Male seta slender, curved in distal portion, about 2/3 length of seta 1 ( Fig. 4K View FIGURE 4 ).
Size. Maximum length of adult parthenogenetic females up to 0.56 mm. Maximum length of ephippial females up to 0.53 mm. Maximum length of adult males up to 0.44 mm.
Variability. In T. aguascalentensis we found males with two basal spines on postabdominal claw and males with single basal spine. Therefore we re-examined material with males from Canada (a sample with accession number AAK M-1192, see details in Neretina et al. (2018)) ( Fig. 5A View FIGURE 5 ). There apart from males with two basal spines on postabdominal claw ( Figs. 5 View FIGURE 5 B–D), we found males only with single basal spine as well ( Figs. 5 View FIGURE 5 E–F). Thus the number of basal spines on claw of male postabdomen is variable, even within the same population.
Also, in males from water accumulated in bromeliads some minor variability concerns proportions of rostrum ( Fig. 4B View FIGURE 4 ) and shape of distalmost portion of postabdomen ( Fig. 4F View FIGURE 4 ). But these deviations were observed only occasionally.
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.