Pleuroxus fryeri, Kotov & Sinev & Berrios, 2010
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publication ID |
https://doi.org/ 10.11646/zootaxa.2430.1.1 |
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persistent identifier |
https://treatment.plazi.org/id/03A987D7-FFE8-3F12-90D9-F9AD3826FCF9 |
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treatment provided by |
Felipe |
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scientific name |
Pleuroxus fryeri |
| status |
sp. nov. |
Pleuroxus fryeri View in CoL sp. nov.
( Figures 10–14 View FIGURE 10 View FIGURE 11 View FIGURE 12 View FIGURE 13 View FIGURE 14 )
? Pleuroxus aduncus (Jurine) in Harding 1955, figs 83–84.
Etymology. This species is named after Dr Geoffrey Fryer, FRS, famous British investigator of the Chydoridae , as well as other Cladocera , other Branchiopoda, other Crustacea and their predators, fish.
Type locality. Crater Lake, Licancabur Volcano (locality 5).
Holotype. Adult parthenogenetic female in 90% alcohol, MGU Ml 81. Label of the holotype: " Pleuroxus fryeri sp. nov., 1 parth. ♀ from Crater Lake, Licancabur Volcano, Chile-Bolivia border, coll. in 04.ii.2007 by V. Gaete, HOLOTYPE ".
Paratypes. 40 parthenogenetic females, MGU Ml 82; 40 parthenogenetic females, AAK 2008–149 .
Other material studied. Five parthenogenetic female from locality 6, AAK 2008-094.
Diagnosis. Parthenogenetic female. Body brown, relatively opaque, high for the genus, postero-ventral angle without a tooth. In anterior view, body moderately compressed laterally, with triangular-rounded dorsum, because top of carapace ridged. Rostrum long, protruding downward and slightly posterior. Head shield elongated, its posteriormost portion rounded, postpore distance (PP) = about 3–4 interpore distance (IP). Labrum with a large medial keel having a well-defined apex, protruding behind tip of rostrum. Valves with a distinct reticulation, within polygons a fine punctuation. All setae on ventral margin exactly marginal except of anterior most portion. A row of small setules on posterior valve margin, with bases located exactly marginally. Postabdomen wide, preanal margin slightly concave, shorter than anal margin, the latter concave, preanal and postanal angle expressed, postanal margin approximately as long as anal margin, dorso-distal angle widely rounded and slightly prominent distally. Postanal margin provided with thin postanal teeth, organised in series of 2–4 members. Postabdominal claw massive, with two basal spines, proximal one being half size of distal one or even shorter. Antenna I small, with a well-defined basal peg. Antennular sensory seta arising at one third of antennular length from distal end directly from antenna I body, without any prominences. Antennal formula, setae 0–0–3/1–1–3, spines 1–0–1/0–0–1. All apical "swimming" setae, as well as basal and distal lateral setae of endopod subequal in size, with chitinous insertions within distal segments. Spine on proximal segment of exopod small. Limb I with accessory seta, outer distal lobe with two setae of different length, inner distal lobe with relatively short, naked first seta, second and third setae subequal in size and similarly armed distally with short setules. Two ejector hooks of subequal size. A remnant of maxillar process with a single seta. Number of setae in filter plates II–V 8–9–6(7)–4. Size up to 1.16 mm.
Ephippial female, male. Unknown.
Description. Parthenogenetic female. Body brownish, relatively opaque. In lateral view body oval, high for the genus (body height/ body length = body height/length = 0.74–0.77 in juveniles, 0.83–0.88 in adults), maximum height in middle ( Figs. 10A View FIGURE 10 , 11A View FIGURE 11 ). Dorsal margin evenly arched from tip of rostrum to postero-dorsal angle, which is ill-defined, posterior margin slightly convex, postero-ventral angle broadly rounded, without any teeth, ventral margin with a slight prominence in middle. Body moderately compressed laterally ( Fig. 11B View FIGURE 11 ), with triangular-rounded dorsum, because top of carapace ridged ( Figs. 10B View FIGURE 10 , 11C View FIGURE 11 ). Head with a long rostrum, protruding downward and posterior ( Fig. 10A, C View FIGURE 10 , 11D–F View FIGURE 11 ). Ocellus smaller than compound eye, lies closer to base of antenna I than to compound eye. Head shield elongated, with maximum width on level of mandibular articulation, its posteriormost portion rounded ( Figs. 10D View FIGURE 10 , 11G View FIGURE 11 ), rostrum with a terminal tubercle ( Figs. 10E View FIGURE 10 , 11F View FIGURE 11 ). Two major head pores ( Figs. 10F View FIGURE 10 ), sometimes a special inner organ associated with head pores is visible under opical microscope and SEM ( Fig. 10G View FIGURE 10 , 11H View FIGURE 11 ); postpore distance = about 3–4 interpore distance ( Fig. 10D View FIGURE 10 ). Lateral head pores minute, normally located asymmetrically to midline ( Figs. 10F–G View FIGURE 10 , 11H View FIGURE 11 ). Labrum with fleshy main body, small distal labral plate and a large medial labral keel, with well-defined apex ( Fig. 10H View FIGURE 10 ), projecting beyong tip of rostrum ( Figs. 10C View FIGURE 10 , 11D–E View FIGURE 11 ) and supplied with 1–2 terminal hillocks ( Figs. 10H–J View FIGURE 10 ). Valves large, with a distinct reticulation ( Fig. 12A View FIGURE 12 ), within polygons a fine punctuation ( Fig. 12B View FIGURE 12 ); in dorsal portion lines of reticulation inflated, forming a sculpture as a series of folds ( Figs. 13A– B View FIGURE 13 ), while in ventral portion reticulation also expressed, but not forming such sculpture ( Figs. 13C–D View FIGURE 13 ). Ventral margin armed with numerous setae of different size in different regions, in anterior portion they are naked and located far from margin ( Fig. 12C View FIGURE 12 ), following setae plumose and located exactly marginally, each of more anterior seta has an expanded basis bearing a spine, following setae longer and lacking expanded bases and spines ( Figs. 12D–G View FIGURE 12 ). A row of minute setules on posterior valve margin, with bases located exactly marginally ( Figs. 12G View FIGURE 12 , 13D View FIGURE 13 ).
Postabdomen wide ( Figs. 12H–I View FIGURE 12 , 13E View FIGURE 13 ), its ventral margin almost straight, preanal margin slightly concave, shorter than anal margin, the latter concave, preanal and postanal angle expressed, postanal margin approximately as long as anal margin, dorso-distal angle widely rounded and slightly prominent distally, inflated basis of claws bordered from postanal margin by a distinct depression ( Figs. 12J View FIGURE 12 , 13F View FIGURE 13 ). Postanal margin provided with thin postanal teeth, organised in series of 2–4 members, they are larger in its distal portion. Laterally on postabdomen series of short, fine setules. Postabdominal seta somewhat longer than preanal margin, with distal segment bearing short, rare setules ( Fig. 12I View FIGURE 12 ). Postabdominal claw shorter than anal margin, massive, evenly curved, with setules along ventral margin, and two basal spines, proximal one being half size of distal one or even shorter ( Figs. 12J–L View FIGURE 12 , 13F View FIGURE 13 ).
Antenna I small, length about 2.5 less than labral keel length, narrowing distally ( Figs. 10C, K View FIGURE 10 , 13G View FIGURE 13 ), with a well-defined basal peg. Antennular sensory seta slender, approximately as long as half the antenna I, arising at one third of antennular length from distal end directly from antenna I body, without any prominences. Nine short aestetascs of slightly differing size. Antenna II ( Figs. 10L View FIGURE 10 , 13H View FIGURE 13 ) relatively short, coxal part with two sensory setae, basal segment robust, with a rudimentary distal spine. Antennal branches relatively elongated, endopod longer than exopod, all segments cylindrical, antennal formula, setae 0–0–3/1–1–3, spines 1–0–1/0– 0–1. All apical "swimming" setae, as well as basal and distal lateral seta of endopod subequal in size, with chitinous insertions within distal segments ( Fig. 10M View FIGURE 10 ). Spine on proximal segment of exopod small. Exopod and endopod apical spines subequal in size.
Limb I ( Figs. 13H View FIGURE 13 , 14A–D View FIGURE 14 ). Distal portion with accessory seta, outer distal lobe (ODL) bears a long terminal seta with distal segment unilaterally armed with minute setules, and a short lateral seta with bilaterally setulated distal segment. Inner distal lobe (IDL) with relatively short, naked first seta, second and third setae subequal in size and similarly armed distally with short setules. Endite 3 with three posterior setae (a–c) and a setulated anterior seta 1 ( Fig. 14B View FIGURE 14 ), all of subequal length. Endite 2 with three posterior setae d–f, and thin anterior seta 2 bilaterally armed with short setules distally ( Fig. 14C View FIGURE 14 ), a small sensillum near the latter. Endite 1 with thin posterior setae g–i, a short seta j, and anterior seta 3 ( Fig. 14D View FIGURE 14 ) somewhat shorter than seta 2, with a sensillum neat its base. Fascicles of thin setules on inner face of limb, plus bunches of longer, thicker setules at ventral margin of limb. Two slender ejector hooks of subequal size. A remnant of maxillar process with a single seta.
Limb II ( Figs. 14E–H View FIGURE 14 ). Exopodite small, subquadrangular, with a short seta. Inner portion of limb with eight scrapers ( Fig. 14E View FIGURE 14 : 1–8), 1–2 longer and armed with fine setules ( Fig. 14G View FIGURE 14 ), others armed distally with thin spinules ( Fig. 14H View FIGURE 14 ), setae 6–8 shortest. A system of small projections posteriorly to scrapers 2–4, and a small sensillum near scraper 4. Distal armature of gnathobase with a bunch of setules and four setae ( Fig. 14F View FIGURE 14 ), a bunch of stout setules distally to seta 1, a bunch of fine setules basally to it. Filter plate II with eight setae.
Limb III ( Fig. 14I View FIGURE 14 ). Epipodite ovoid, exopodite sub-rectangular, with four distal setae (1–4) and three lateral setae (5–7). Distal endite with three anterior setae ( Fig. 14J View FIGURE 14 : 1–3), basalmost seta (3) shorter, small sensillae near bases of setae 2 and 3. Basal endite with four anterior setae ( Fig. 14J View FIGURE 14 : 4–7), slightly increasing in size basally, armed with fine setules distally, a small bottle-shaped sensillum near seta 4. On posterior surface, six soft setae ( Fig. 14I View FIGURE 14 ), bilaterally armed with fine setules. Gnathobase not clearly separated from basal endite. Distal armature of gnathobase with a large, bottle-shaped sensillum, three setae, and a bunch of setules ( Fig. 14J View FIGURE 14 : 1–4), filter plate III with nine setae.
Limb IV ( Fig. 14K–L View FIGURE 14 ). Pre-epipodite rounded, setulated; epipodite without a finger-like projection; exopodite wide, subovoid, with seven setae of unequal size ( Fig. 14K View FIGURE 14 : 1–7). Inner-distal portion of limb IV with four marginal setae ( Fig. 14L View FIGURE 14 : 1–4). Distalmost seta (1) stout, naked, setae 2–4 setulated, with thick distal segments, sensillae located near setae 2 and 3. On posterior surface, four soft setae ( Fig. 14K View FIGURE 14 ). Distal armature of gnathobase with four setae ( Fig. 14L View FIGURE 14 : 1–4), filter plate with six, rarely seven setae.
Limb V ( Fig. 14M View FIGURE 14 ). Pre-epipodite setulated; epipodite subovoid, without a finger-like projection; exopodite large, subovoid, with a single distal seta 1 and three lateral setae (2–4), distally to seta 1 there are two projections bearing long setules. Inner limb portion as elongated, flat lobe, with setulated inner margin, supplied with setulated setae 1 and 2. Distal armature of gnathobase as a single projection, filter plate V with four long setae.
One to two parthenogenetic eggs in brood pouch.
Ephippial female, male. Unknown.
Size. Holotype 1.13 mm, parthenogenetic females 0.69–1.16 mm.
Differential diagnosis. Among aduncus -like taxa of the southern hemisphere ( Frey 1993; Smirnov et al. 2006), only P. fryeri sp. nov. and P. scopuliferus Ekman, 1900 have (1) top of carapace ridged (triangular in anterior view); (2) filter plate of gnathobase III of nine setae. The former differs from the latter in (1) head shield rounded posteriorly; (2) rostrum shorter, not projecting behind apex of labral keel; (3) no denticles at postero-ventral angle; (4) quite projected peg on antenna I; (5) significantly greater size.
P. fryeri sp. nov. is the fourth species of South American Pleuroxus which is brown, not transparent. It differs from P. scopuliferus as described below, from P. paraplesius Frey, 1993 having no denticles at posteroventral angle, from P. hardingi Smirnov et al., 2006 in well-developed basal peg of antenna I and all setae on ventral margin exactly marginal.
Distribution. It is known only from two localities, Crater Lake in Licancabur Volcano, and Laguna Leja, both in Atacama Desert, North Chile. Harding (1955) illustrated " P. aduncus " from Lagunillas pond in vicinities of Lake Titicaca, habitually similar to our taxon. Unfortunately, description and figures are lacking many important details, and we can finally confirm the presence of P. fryeri sp. nov. in the vicinities of Lake Titicaca. In any case, P. fryeri sp. nov. is an Andean endemic.
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.