Magnospina siamensis, Sousa, Francisco Diogo R., Elmoor-Loureiro, Lourdes Maria Abdu & Santos, Sandro, 2016

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 : 103-104

Taxon classification Animalia Diplostraca Chydoridae

Magnospina siamensis comb. n.

Alona siamensis : Sinev and Sanoamuang 2007: 145, 147-148, figures 1-30; Van Damme and Sinev 2013: 226-228; Korovinchinsky 2013: 114, 119, tables 1-2.

Coronatella dentifera (Sars, 1901): Chartejee et al. 2013: 43.

Type locality.

Rice field at Ban Bayao Baghe Sub-district, Phannanichom District, Sakhonnakhon Province, Thailand, 01.09.2004.

Material type.

Holotype: parthenogenetic female, ZMMU, MI-73. Paratypes: 2 parthenogentic females, ZMMU, MI74.

Differential diagnosis.

Magnospina siamensis comb. n. differs from Magnospina dentifera comb. n. because it has a truncated rostrum, three connected main head pores, minute lateral head pores and a prominent sculpture on the carapace. Apical spines of the antenna are longer than the apical segments. On the limbs, the main differences are: IDL is armed with two setae (2-3), seta 2 with two thick basal denticles, seta 3 with one thick basal denticle, limb V without filter comb.

Diagnosis.

Female. According to the literature ( Sinev and Sanoamuang 2007).

Habitus without dorsal keel, moderately compressed laterally, length 0.35-0.42 mm; eye and ocellus of subequal sizes. Head with rostrum wide, truncated; head shield ornamented with longitudinal lines, wide, posterior margin broadly rounded, distance between mandibular articulations higher than length of its posterior portion, three connected main head pores, lateral head pores minute. Labral keel wide, oval and naked, apex not elongated. Carapace covered with narrow longitudinal lines; ventral margin of carapace with a distinctive rounded angle at 1/3 of length; valves armed with 45 setae internally inserted at the ventral margin and differentiated in three groups, setae from anterior group markedly longer; posteroventral corner armed with 2-3 large denticles, broad at their bases, protruding downwards, without setules between them. Antennule do not exceed the tip of the rostrum, nine apical aesthetascs of different length which do not exceed the length of the antennular body. 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 the second segment; apical spines longer than the apical segments. Postabdomen narrowing distally, length about 2.5 it is height; preanal angle prominent; postanal margin about 1.7-1.8 times longer than the anal margin armed with 3-4 single most distal denticles and 5 cluster of denticles; About 10 lateral fascicles with weak setules. Postabdominal claw inserted on the projection of postabdomen, longer than anal margin; base of claw armed with 1-2 long and strong spinules. Basal spine remarkably long, longer than 2/3 of postabdominal claw length, without spinules on the dorsal margin. Limb I with two thick setae (2-3) on the IDL (en 4), seta (2) with two thick basal denticles, seta (3) with one thick basal denticle; setae (1, a-c) on the endite 3 of subequal length, endite 3 without element; endite 2 armed with three setae (d-f), without element; endite 1 with three setae (g-i). Limb II without anterior soft setae; seta on the exopod short, not 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 the others. Limb III with six setae on the exopod, third and fourth setae long; third seta slightly shorter than the second seta; distal endite armed with three setae and one sensillum; gnathobase with three elements, filter comb with seven setae. Limb IV relatively short, six setae on the exopod; setae 1-2 of similar lengths; flaming-torch setae on the distal endite not modified, setules on the first flaming-torch relatively longer that one observed in setae 2-3; gnathobase armed with a setulated seta shorter than length of endite itself, filter comb with five setae. Limb V with setae 3-4 of exopod similar in lengths; filter comb absent. Limb VI absent.

Ephippial female and male. Unknown.

Distribution.

Malysia, Thailand (Sinev 2007; Van Damme and Sinev 2013; Korovinchinsky 2013) and probably India ( Chartejee et al. 2013).