Alona isabellae, Francisco Diogo R. Sousa, Lourdes M. A. Elmoor-Loureiro & Sandro Santos, 2016

Francisco Diogo R. Sousa, Lourdes M. A. Elmoor-Loureiro & Sandro Santos, 2016, New findings of Hexalona-branch representatives in Brazil, with a description of Prenda gen. nov. (Crustacea: Anomopoda: Aloninae), Journal of Natural History 50 (43), pp. 1-42 : 23-28

Alona isabellae sp. nov.

( Figures 7 – 8 , 11 )

Alona intermedia Sars, 1862 in Sousa and Elmoor-Loureiro (2006, 2012 , 2013).

Type locality

Bonita Pond, Estação Ecológica de Águas Emendadas, Distrito Federal, Brazil (15° 35 ʹ 22.4 ʺ S, 47°41 ʹ 49.0 ʺ W).

Type material

Holotype: undissected, adult parthenogenetic female in a tube with 92% ethanol deposited at the Museum of Zoology of the State University of Bahia under accession number UFBA2167 . The label of the holotype is: ‘ Alona isabellae , 1 parth. ♀ from Bonita Pond, Estação Ecológica de Águas Emendadas , Distrito Federal, Brazil. Holotype ’.

Material examined

Paratypes: Distrito Federal: Twenty-four adult parthenogenetic females from Bonita Pond, Estação Ecológica de Águas emendadas, Distrito Federal, Brazil (15°35 ʹ 22.4 ʺ S, 47°41 ʹ 49.0 ʺ W), material collected by Lourdes M.A. Elmoor-Loureiro on 3 May 2005 (EL00750-751); Maria do Socorro Ibañez on 5 July 2001 (EL00681); and GEEA on 10 March 2009 ( FDRS 0080), 27 May 2008 ( FDRS 081), 12 September 2009 (FDR082). Three adult parthenogenetic females from Henrique pond, Brasilia National Park, Distrito Federal, Brazil (15°41 ʹ 18.00 ʺ S, 47°56 ʹ 26.10 ʺ W), material collected by GEEA in August 2009 ( FDRS 071-72). One adult parthenogenetic female from Exercito pond, Brasilia National Park, Distrito Federal, Brazil (15°44 ʹ 44.30 ʺ S, 47°58 ʹ 49.10 ʺ W), material collected by GEEA in August 20109 ( FDRS 073). Four adult parthenogenetic females from Bananal stream, Brasilia National Park, Distrito Federal, Brazil (15°44 ʹ 51.2 ʺ S, 48° 0 ʹ 33.3 ʺ W), material collected by Lourdes M.A. Elmoor-Loureiro on 13 March 2012 (EL02144) and GEEA on 28 February 2013 (EL02497). One adult parthenogenetic female from Cedro pond (15°53 ʹ 49.7 ʺ S, 47°56 ʹ 36.6 ʺ W), material collected by GEEA on 19 September 2009 ( FDRS 079). Nineteen adult parthenogenetic females from Taquara Pond, Distrito Federal, Brazil (15°38 ʹ 12.4 ʺ S, 47°31 ʹ 22.0 ʺ W), material collected by GEEA on 15 August 2006 ( FDRS 083) and 28 August 2008 ( FDRS 084). One adult parthenogenetic female from Joaquim Medeiros pond, Distrito Federal, Brazil (15° 38 ʹ 15.9 ʺ S, 47°41 ʹ 29.5 ʺ W), material collected by GEEA on 2 September 2008 ( FDRS 085). Two adult parthenogenetic females from Brejinho stream, Estação Ecológica de Águas Emendadas, Distrito Federal, Brazil (15°35 ʹ 42.3 ʺ S, 47°37 ʹ 12.9 ʺ W), material collected by GEEA on 19 September 2008 ( FDRS 087). One adult parthenogenetic female from Sobradinho Stream, Distrito Federal, Brazil (15°38 ʹ 15.9 ʺ S, 47°41 ʹ 29.5 ʺ W), material collected by GEEA on 18 August 2009 ( FDRS 088). Two adult parthenogenetic females from Gansos Pond, Distrito Federal, Brazil (15°40 ʹ 33.1 ʺ S, 47°41 ʹ 37.4 ʺ W), material collected by GEEA on 8 August 2006 ( FDRS 0437). Three adult parthenogenetic females from Pipiripau stream, Distrito Federal, Brazil (15°39 ʹ 53.2 ʺ S, 47°38 ʹ 44.0 ʺ W), material collected by GEEA on 17 March 2009 ( FDRS 0438). Goiás: Six adult parthenogenetic females from Grande Pond, Campo de Instrução de Formosa, Formosa, Distrito Federal, Brazil (15°49 ʹ 35.70 ʺ S, 47°13 ʹ 49.40 ʺ W), material collected by GEEA in December and 7 August 2009 ( FDRS 074-75; EL01749). Two adult parthenogenetic females from Cabocla II Pond, Campo de Instrução de Formosa, Formosa, Distrito Federal, Brazil (15°48 ʹ 21.00 ʺ S, 47°14 ʹ 0 9.20 ʺ W), material collected by GEEA in December 2009 ( FDRS 076 – 77). Six adult parthenogenetic females from wetland from Emas National Park, Mineiros, Goiás, Brazil (18°16 ʹ 10.9 ʺ S, 52° 45 ʹ 17.9 ʺ W), material collected by Valeria Barros on 21 April 2000 (EL00683 – 684). Three adult parthenogenetic females from Rio Formosa, Emas National Park, Mineiros, Goiás, Brazil (18°15 ʹ 34.0 ʺ S, 52°53 ʹ 18.7 ʺ W), material collected by Valeria Barros on 1 July 2001 (EL00686-688). One adult parthenogenetic female from a small dam, Cocalzinho, Goiás, Brazil (15° 45 ʹ 12.2 ʺ S, 48°40 ʹ 0 7.5 ʺ W), material collected by Lourdes M.A. Elmoor-Loureiro on 30 September 2000 (EL0250). Ten parthenogenetic females from Estiva stream, Chapada dos Veadeiros National Park, Goiás, Brazil (14°06 ʹ 40.3 ʺ S, 47°44 ʹ 0 2.2 ʺ W), material collected by GEEA on 13 March 2013 (EL02372). One juvenile from Stream 1, Chapada dos Veadeiros National Park, Goiás, Brazil (14°06 ʹ 13.5 ʺ S, 47°42 ʹ 19.5 ʺ W), material collected by GEEA on 13 March 2013 (EL02388). One adult parthenogenetic female from Sete Lagoas, Chapada dos Veadeiros National Park, Goiás, Brazil (14°04 ʹ 26.5 ʺ S, 47° 39 ʹ 40.7 ʺ W), material collected by GEEA on 14 March 2013 (EL02369). Minas Gerais: Six parthenogenetic females from Preto River, Sempre Vivas National Park, Minas Gerais, Brazil (17°55 ʹ 28.6 ʺ S, 43°48 ʹ 32.4 ʺ W), material collected by Adriana Marinho Fernandes in May 2010 (EL01861 EL0161). Twenty-five adult parthenogenetic females from Jequitaí River, Sempre Vivas National Park, Minas Gerais, Brazil (17°53 ʹ 35.9 ʺ S, 43° 47 ʹ 38.7 ʺ W), material collected by Adriana Marinho Fernandes on 3 May 2010 (EL01936). One adult parthenogenetic female from Inhacica River, Sempre Vivas National Park, Minas Gerais, Brazil (17°50 ʹ 11.4 ʺ S, 43°45 ʹ 58.6 ʺ W), material collected by Adriana Marinho Fernandes on 4 May 2010 (EL01866). Rio Grande do Sul: Six adult parthenogenetic females from pond at Lagoa do Peixe National Park, Rio Grande do Sul, Brazil (31º02 ʹ S, 50º77 ʹ W), material leg. Dr. Cristina Stenert ( FDRS 0439).

Diagnosis

Female. Carapace oval, with posterior margin slightly elongated; maximum height at middle of body, body height/length ratio about 0.60, not laterally compressed. Head with ocellus and eye of similar sizes. Two main pores connected; PP about 0.5 – 0.6 IP; lateral head pores tiny. Labrum with 2 – 4 short and fine spinulae of similar size; clearly separated; posterior margin with two clusters of setulae. Carapace armed with longitudinal lines; ventral margin concave near half-length of body, with 42 – 45 plumose setae forming three groups; inner proximal spinulae longer and thicker than others and projected beyond the margin, arranged in 2 – 3 groups. Antennule about 2.6 times longer than wide, armed with nine aesthetascs, two long aesthetascs similar in length to antennular body. Antenna: antennal formula: spines 001/101, setae 113/003; median segment of exopod and endopod long, similar in length to apical segments; seta on first segment of exopod thin, not exceeding the length of branches of the antenna.

Postabdomen relatively long, about 2.6 times as long as wide; distal portion broadly rounded; first spinule of distalmost fascicles thicker than others and exceeding the postabdomen margin and level of the marginal denticles; eight marginal denticles, proximal merged and organised in groups. Potabdominal claw about 0.3 of the length of the postabdomen, with one group of short spinulae on base; pecten armed with a row of inner and outer spinulae; outer row with spinulae of similar length; distal spinulae on inner row longer than others. Basal spine about 1.7 times longer than width of claw base; basal spines armed with spinulae. Limb I with IDL with three groups of spinulae on its face, three setae present; seta 1 relatively short, about half length of seta 2, naked; second endite armed with anterior two elements. Limb II with elongated exopod, one setulated seta present; inner portion of limb armed with two elements; scrapers 4 – 5 and 6 – 7 of similar length. Limb III with seven setae on the exopod; setae 6 – 7 of different lengths. Limb IV with six setae on the exopod, 3 – 6 plumose; second and first seta armed with short setulae. Limb V with incursion between lobes of exopod relatively deep, armed with four setae; filter plate bearing three naked setae. Limb VI present, 1.7 times longer than width.

Male. Unknown.

Ephipial female. Unknown. Ephipium covered by

brownish.

dense

longitudinal lines, pale

Description

Parthenogenetic females. Habitus ( Figures 7 A – C, 11K). In a lateral view, the carapace is oval with posterior margin slightly elongated, maximum height at middle of body, body height/length ratio about 0.60, not laterally compressed. Dorsal margin curved. Dorsal keel absent.

Head ( Figures 7 A – B). Ocellus and eye of similar size. Head shield with maximum width behind the mandibular articulation, line of the posterior margin straight and angular. Rostrum short, rounded, in lateral view projected towards ventral margin of carapace. Two connected main pores, of similar sizes, connection relatively narrow; PP about 0.5 – 0.6 IP; lateral head pores tiny, located at level between main head pores, distance from midline about 2 times shorter than IP. Labrum ( Figures 7 K – N, 11L). Anterior margin convex, armed with 2 – 4 short and fine spinulae of similar sizes, clearly separated; posterior margin with two clusters of setulae; apex rounded.

Carapace ( Figure 7 A – E). Covered with longitudinal lines; ventral margin concave near half length, with 42 – 45 plumose setae per valve forming three groups, groups with long setae (anterior and posterior) separated by a group of short setae. Posterior margin straight, armed with long and rosbust internal spinulae: spinulae at posteroventral corner longer and thicker than others and projected beyond the margin, arranged in 2 – 3 groups.

Antennule ( Figure 7 I). Not exceeding the length of rostrum, about 2.6 times longer than wide; four rows of short setulae on antennular body. Antennular sensory seta slender, about 1.7 times smaller than antennular body, inserted in last third of antennule length at its base. Nine aesthetascs projecting beyond the tip of rostrum, two long aesthetascs similar in length to antennular body present.

Antenna ( Figure 7 J). Coxal setae not studied. Basal segment thick, with a short spine and spinulae. Antennal formula: spines 001/101, setae 113/003. Median segment of the exopod and endopod longer than apical segments. Seta on first segment of exopod thin, armed with fine setulae, not exceeding the length of branches of antenna. Seta on second segment of exopod bisegmented, about 1.5 times longer than shorter apical seta. Spine on first segment of endopod short, exceeding half of the length, but not reaching the end of the second segment. Apical spines of the endopod and exopod similar in length to apical segments of antenna. Apical setae bisegmented and setulated. All segments have spinulae at the terminal portion; setulae on the second segment of the exopod long.

Abdomen about 2 times shorter than thorax. Two rows of abdominal setae.

Postabdomen ( Figures 7 O, 11M – N). Relatively long, about 2.6 times as long as wide, ventral margin slightly rounded, with two rows of short spinulae. Distal portion broadly rounded. Anal margin very long, occupying about 60% of the postabdomen length. Nine lateral fascicles armed with thin and long spinulae; first spinule of fascicles thicker than others, exceeding the postabdomen margin and the level of the marginal denticles; eight marginal denticles increasing in length towards distal portion; denticles bear spinulae on the anterior margin; the proximalmost denticles grouped.

Postabdominal seta ( Figure 7 A – B). About 2 times shorter than postabdomen length, bisegmented; setulae on proximal segment short when compared to setulae of distal segment. Postabdominal claw ( Figures 7 O, 11M). About 0.3 of length of postabdomen; implanted at projected short basis from the postabdomen, uniformly curved, with one group of short spinulae on base itself; pecten armed with one row of inner and outer spinulae; outer row with spinulae of similar length; distal spinulae on inner row longer than others. Basal spine ( Figures 7 O, 11M). About 1.7 times longer than width of claw at its base; basal spines armed with spinulae that reach the distal portion.

Mandibles not studied. Maxilla ( Figure 8 A). Armed with two setulated setae.

Six pairs of limbs.

Limb I ( Figure 8 B – D). Epipod oval with a long projection. Accessory seta short, similar in length to base of ODL, which has a seta armed with long setulae in the distal part, shorter than length of seta 3 of the IDL. IDL (en4) with three groups of spinulae on its face, three setae present; seta 1 relatively short, about half length seta 2, naked; setae 2 and 3 of different length, bisegmented and armed with setulae. Endite 3 with four setae; posterior setae (a – b) longer than posterior seta 1 on the endite. Endite 2 with two rows of spinulae; three posterior setae present (d – f), seta (f) 0.7 times shorter than seta (e), both setae have thick spinulae on the lateral face; endite armed with two minute elements inserted near to base of seta (d); seta (d) setulated and exceeding half the length of seta (e). Endite 1 with three posterior setae (g – i); setae (g) and (h) bisegmented and densely setulated in distal part, of similar length; seta (i) relatively short, about 0.2 of setae (g) and (h). Ejector hooks of similar length and armed with short denticles. Ventral face of the limb with eight groups of setulae organised in clusters, decreasing towards the distal portion. Gnathobase elongated; setulae were not observed on the gnathobase.

Limb II ( Figure 8 E – F). Exopod elongated, with two rows of setulae, distal row longer than proximal; one seta setulated at distal portion present, about 1.8 times shorter than its exopod itself. Inner limb portion armed with eight scrapers and two elements; scraper 3 shorter than 2 and similar in length to scrapers 4 and 5; scrapers 6 – 7 of similar length. Scrapers 1 – 4 armed with fine spinulae; scrapers 5 – 8 armed with fine spines. Proximal portion of the gnathobase short, apex armed with setulae; distal portion armed with four elements, first as a robust sensillum, second as element with distal portion acute and slightly geniculated, third element armed with denticles, fourth element short and obtuse. Filter comb with seven setae; first and second setae short; other setae long and slightly setulated (setulae not showed on the figures).

Limb III ( Figure 8 G – I). Epipod oval, with short projection. Exopod subquadrangular, with five distal and two lateral setae. Seventh seta setulated and about 1.8 times longer than sixth seta; sixth seta setulated. Fifth seta long, armed with proximal short setulae, distal setulae relatively long, about 1.6 times longer than second seta. Fourth and third setae setulated and similar in length. Second seta about 2.7 times longer than first seta; armed with long setulae from median portion. First seta slightly setulated. Distal endite armed with one sensillum and three setae (1 – 3), two scraper-like of different lengths (1 – 2); third seta curved and armed with many setulae bilaterally implanted (3); four plumose posterior setae similar in length (a – c). Basal endite with four soft anterior setae increasing in length towards the gnathobase. Gnathobase armed with four elements, the first being a cylindrical sensillum, the second a geniculated seta and third and fourth elements with tip acute, naked. Filter comb with seven setae (setulae not showed on the figures).

Limb IV ( Figure 8 J – L). Pre-epipod rounded and densely setulated. Epipod oval with a long projection. Exopod subquadrangular with six marginal setae; setae 3 – 6 plumose; setae 4 – 6 similar in length; third seta short, about 3.5 times shorter than second seta; setae 1 – 2 of similar length, armed with short setulae. Distal endite with a sensillum and four setae (1 – 4), one scraper-like (1), three flaming torch-like (3 – 4); the first flaming torch relatively robust, with long setulae (2). Basal endite with three soft setae slightly setulated, increasing in length towards gnathobase. Gnathobase armed with one globular sensillum and a setulated setaimplanted on a robust base. Filter plate with five setae (setulae not shown in the figures).

Limb V ( Figure 8 M – N). Pre-epipod rectangular and densely setulated, epipod oval with long projection. Exopod divided into two lobes, incursion between lobes relatively deep; four plumose setae present; setae 3 – 4 similar in length, about 1.3 times longer than seta 2; first seta about 2.7 times shorter than seta 2. Internal lobe wide, oval and with long setulae; two setulated setae on inner face of lobe, first seta longer than length of lobe. Gnathobase armed with an inflated element; filter plate armed with three naked setae.

Limb VI ( Figure 8 O – P). An elongated lobe, relatively rounded, about 1.7 times longer than width of lobe; apical margin of lobe with long setulae; only one lateral margin is totally setulated and is armed with short or long setulae.

Male. Unknown.

Ephipial female. Unknown. Ephipium ( Figure 7 P – Q) covered by dense longitudinal lines, pale brownish; weak lateral compression.

Size. The length of the adult parthenogenetic females are 0.30 – 0.34 mm. In juvenile females, the length was 0.28 – 0.29 mm.

Remarks. Alona isabellae sp. nov. clearly resembles A. intermedia ( Alonso 1996; Flössner 2000) and A. elisae sp. nov. However, it has a unique armature of the labral keel and setulae of lateral fascicles on the postabdomen. Specifically, A. isabellae sp. nov. differs from A. elisae sp. nov. because it has first seta of the IDL and setae of the filter comb of the fifth limb naked. The postabdomen of A. isabellae sp. nov. bears spinulae of lateral fascicles longer than the level of the marginal denticles, internal setulae are armed in 2 – 3 groups on the posterior margin of carapace and antennule with two long aesthetascs. The limbs of A. isabellae sp. nov. are less robust when compared to those of A. elisae sp. nov., and the main differences were observed on the first, second and fifth limbs. On the first limb, A. isabellae sp. nov. has two elements, not observed in A. elisae sp. nov.

Geographical distribution. Alona isabellae sp. nov. has a wide distribution in Brazilian territory, occurring in Brazil ’ s Central, Sourthern and South regions. This species may be found in shallow lakes, ponds and lotic ecosystems.

Figures

Figure 7. Alona isabellae sp. nov. (A) Habitus from parthenogenetic female, Distrito Federal; (B) idem, Minas Gerais; (C) marginal setae of carapace; (D – E) posteroventral corner of carapace; (F) head shield; (G – H) head pores; (I) antennule; (J) antenna; (K – N) labral keel; (O) postabdomen; (P) ephipium, lateral view; (Q) idem, dorsal view. Scale bars = 50 µm.

Figure 8. Alona isabellae sp. nov. from Bonita pond, Distrito Federal. (A) Maxilla; (B) limb I; (C) idem; (D) idem – ODL and IDL; (E) limb II; (F) idem, exopod; (G) limb III, exopod and distal endite; (H – I) idem, endites; (H) distal endite; (I) basal endite; (J) limb IV, exopod; (K – L) idem, endites; (K) distal endite; (L) basal endite; (M) limb V; (N) idem, internal lobe; (O – P) limb VI. For abbreviations, see Material and methods. Scale bar = 50 µm.

Figure 11. (A – C) Alona cf. guttata: (A) habitus from parthenogenetic female; (B) labral keel; (C) postabdomen. (D – G) Alona elisae sp. nov., holotype: (D) habitus from parthenogenetic female; (E) labral keel; (F) postabdomen; (G) idem, lateral fascicles; (H) habitus from male; (I) male, labral keel and hook; (J) male, postabdomen. (K – N) Alona isabellae sp. nov., holotype: (K) habitus from parthenogenetic female; (L) labral keel; (M) postabdomen; (N) idem, lateral fascicles. (O – R) Prenda arvensis gen. nov. and sp. nov., holotype: (O) labral keel; (P) postabdomen; (Q) limb I; (R) limbs IV, V and VI. For abbreviations, see Material and methods. Scale bars: B, C, E, F, I, J, M, O – R = 25 µm; A, D, H, K = 50 µm.