Magnospina dentifera (Sars, 1901) Sars, 1901

Sousa, Francisco Diogo R., Elmoor-Loureiro, Lourdes Maria Abdu & Santos, Sandro, 2016, Position of the dentifera-group in the Coronatella-branch and its relocation to a new genus: Magnospina gen. n. (Crustacea, Chydoridae, Aloninae), ZooKeys 586, pp. 95-119 : 100-103

Taxon classification Animalia Diplostraca Chydoridae

Magnospina dentifera (Sars, 1901) comb. n. Figures 1-7, 8-15, 16-26, 27-33

Alona dentifera (Sars, 1901): Sinev et al. 2004: 101, 103-104, figures 1-39; Güntzel et al. 2010: 95, table 1; Sousa and Elmoor-Loureiro 2012: 356, table 2; Debastiani-Júnior et al. 2015: 24, table 2.

Alona broaensis : Matsumura-Tundisi and Smirnov 1984: 327-328, figures 15-21; Güntzel et al. 2010: 95, table 1; Debastiani-Júnior et al. 2015: 24, table 2.

Type locality.

"neighborhood of São Paulo", State of São Paulo, Brazil.

Material type.

Lectotype: Parthenogenetic ♀, ZMOU F12341a, selected by D. Frey. Paralectotype: 5 parthenogenetic ♀♀, ZMOU F12341b; 1 parthenogenetic ♀ F12341c; 4 parthenogenetic ♀♀, I instar juvenile ♀, ZMOU F12386g; 2 instar II juvenile ♀ ZMOU F12386q; 2 partenogenetic ♀♀, instar II juvenile #, ZMOU, slide F 9130; 6 parthenogenetic ♀♀, ephippial ♀, ZMOU, slide F9131; 2 parthenogenetic ♀♀, ephippial ♀, ZMOU, slide F9131.

Material examined.

Nine parthenogenetic females and one adult male from Henrique pond, Brasília National Park, Distrito Federal, Brazil (15°41'18"S; 47°56'26.10"W), material collected by Grupo de Estudos de Ecossistemas Aquáticos (GEEA) in ix.2009 (FDRS048). One parthenogenetic female from Henrique pond, Brasília National Park, Distrito Federal, Brazil (15°41'16.5"S; 47°56'22.2"W), material collected by Lourdes M. A. Elmoor-Loureiro on 27.v.2002 (FDRS049). One parthenogenetic female from Cabocla II pond, Campo de Instrução de Formosa, Goiás, Brazil (15°48'21"S; 47°17'09.20"W), material collected by Grupo de Estudos de Ecossistemas Aquáticos (GEEA) on viii.2009 (FDRS050). Six adult parthenogenetic females and one juvenile from Baía da Célia, Fazenda Nhumirim (18°59'27.5"S, 56°39'41.0"W), Pantanal, Mato Grosso do Sul, Brazil, material collected on 07.ix.2000 by Valéria Barros. Four parthenogenetic females from Criminosa Pond (21°40'28.8"S, 57°53'28.5"W) identified as Alona broaensis , Porto Murtinho, Pantanal, Mato Grosso do Sul, Brazil, material collected on 19.i.2010, leg Adriana Maria Güntzel (FDRS054). Two parthenogenetic females from Coqueiral Pond, Paranapanema River, Angatuba, São Paulo, Brazil (23°29'22.64"S; 48°37'6.65"W). Material collected by Lourdes M. A. Elmoor-Loureiro on 30.v.2001 (CLLA063, 65-66). Two parthenogenetic females from Esquina, Middle Paraná River, Argentina (30°00.54'59"S; 59°32'51.93"W). Material collected by José Roberto Debastiani Júnior on 12.vi.2010 (FDRS052). Six parthenogenetic females from San Pedro, Lower Paraná River, Argentina (30°40'49"S; 59°18'48.80"W). Material collected by José Roberto Debastiani Júnior on 14.vi.2010 (FDRS053). Three parthenogenetic females from Pimenteira pond, Mata da Pimenteira State Park, Serra Talhada, Pernambuco, Brazil (7°53'48.96"S, 38°18'14.30"W). Material collected by Leidiane Pereira Diniz on 13.iv.2014 (FDRS407).

Differential diagnosis.

Magnospina dentifera comb. n. differs from Magnospina siamensis comb. n. because it has a rounded and wide rostrum and main and lateral head pores are absent in adult. Apical spines of the antenna about two times shorter than the apical segments. On the limbs, the main differences are: Magnospina dentifera comb. n. bears a rudimentary seta 1 on the IDL, setae 2-3 of IDL armed with at least seven denticles and the presence of one seta on the filter comb of limb V.

Diagnosis.

Habitus ovoid, without dorsal keel, not compressed laterally, length 0.32-0.48 mm; eye and ocellus of different sizes. Head with rostrum wide, rounded, not pointed; head shield wide, with broadly rounded posterior margin, distance between mandibular articulations higher than length of its posterior portion, main head pores absent in adults, two or three connected main head pores in juveniles (Figures 8-9); lateral head pores absent. Labral keel wide, large and naked, apex not elongated (Figure 10). Carapace ornamentation slightly punctuated or not evident; ventral margin of carapace with a distinctive rounded angle at 1/3 of length; valves armed with 40-53 setae internally inserted at the valve ventral margin and differentiated in three groups, setae from anterior group markedly longer than median and posterior groups (Figures 1-6); posteroventral corner armed with 1-4 large denticles, broad at their bases, protruding downwards, without setules between them (Figure 7). Antennule do not exceed the tip of the rostrum, nine apical aesthetascs of different lengths which do not exceed the length of the antennular body (Figure 11). Antenna with formula of antennal setae 003/113, spines 101/001; first segment of endopod and exopod elongated; weak setules or spicules on the segments; spine on the first segment of the endopod longer than second segment length; apical spines about two times shorter than the apical segments (Figure 12). Postabdomen narrowing distally, length about 1.3 times its height; preanal angle prominent; postanal margin about 1.5 times longer than the anal margin armed with 10-13 groups of denticles, 1-3 most distal denticle might be individualized; 8-10 lateral fascicles armed with weak setules (Figures 13-14). Postabdominal claw inserted on the projection of postabdomen, longer than anal margin; spinules on the ventral margin may be present; pecten of spinules on the internal and external face of the claw, base of claw armed with 1-5 long and strong spinules (Figures 14-15). Basal spine remarkably long, longer than 2/3 of postabdominal claw length, with spinules on the dorsal margin (Figures 14-15). Limb I with IDL (en 4) armed with one rudimentary seta (1) and two well-developed setae (2-3) which bears at least seven distinguishable denticles, basal denticles thick; seta (1) on endite 3 shorter than setae (a-c), setae (a-b) of different length, endite 3 with an element; endite 2 armed with three setae (d-f), element present; endite 1 with three setae (g-i) (Figures 16-19). Limb II without anterior soft setae; seta on the exopod short, slightly plumose; scrapers not specialized, but with some denticles, especially on scrapers 6-8; gnathobase armed with four elements, filter comb armed with seven setae, of which two are shorter than others (Figure 20). Limb III with six setae on the exopod, third and fourth setae long; third seta longer than the second seta; distal endite armed with three setae and one sensillum; gnathobase with three elements, filter comb with seven setae (Figures 21-22). Limb IV relatively short, six setae on the exopod; setae 1-2 of different lengths, flaming-torch setae on the distal endite not modified with weak setules; gnathobase armed with a setulated seta shorter than the length of endite itself, filter comb with five setae (Figures 23-26). Limb V relatively short, setae 3-4 of exopod similar in length; filter comb reduced with one short seta (Figures 25-26). Limb VI absent.

Ephippial female. Not studied.

Adult male. Habitus smaller than female (Figure 27). Postabdomen strongly narrowing distally. Postabdominal claw short and ticker than female (Figures 30-31). Basal spine about half-length of postabdominal claw, with tip forked (Figure 31). Limb I with two setae on the IDL (en4), setae armed with denticles; male seta with tip slightly curved; copulatory hook with one projection on the tip (Figures 32-33).

Description of adult male.

Habitus ovoid, smaller than that in female, length about 0.35 mm, maximum height in the middle of the body (Figure 27). Head with rostrum elongated, not blunt, main head pores absent (Figure 27). Carapace without ornamentations; ventral margin with a distinctive rounded angle at 1/2 of the margin length, margin armed with about 37 setae, posteroventral corner with two large denticles, broad at their bases, without setules between them (Figure 27). Antennule not exceeding the tip of rostrum, about 2.5 times as long as it is wide, with three rows of short setules on body antennular; eleven aesthetascs, two lateral and nine apical ones. Sensory seta and male seta not studied (Figures 27-28). Antenna as described for females, however, apical spines relatively longer (Figure 29). Postabdomen as long as in female, strongly narrowing distally. Anal margin shorter than postanal margin; 12 rows of thin setules on the anal and postanal margin; eight lateral fascicles with weak setules of which do not exceed postanal margin (Figure 30). Postabdominal claw smaller and more robust as comapared with female, base armed with long and strong spinule, pecten armed with strong spinules at the median portion of the claw (Figures 30-31). Basal spine long, about half-length of postabdominal claw, with a forked tip, ventral margin armed with spinules (Figure 31). Limb I with copulatory hook curved, U-shaped, projection at the tip present, copulatory brush seta shorter than male seta on IDL (en4), the latter armed with three setae; male setae thick with tip slightly curved; setae 2-3 armed with proximal denticles (as observed in female); ODL seta longer than IDL setae (Figures 32-33).

Distribution.

Neotropics, from Southern U.S.A to Argentina ( Sinev et al. 2004).