Brasilocypria namiotkoi, Almeida, Nadiny Martins De, Ferreira, Vitor Góis, Martens, Koen & Higuti, Janet, 2023

Almeida, Nadiny Martins De, Ferreira, Vitor Góis, Martens, Koen & Higuti, Janet, 2023, 5237, Zootaxa 5237, pp. 1-88 : 55-57

Brasilocypria namiotkoi gen. et spec. nov.

( Figs 34–37 )

Diagnosis. Cp and valves elongated in lateral view in males (L almost 2 x H), suboval in females, LV overlapping RV, except in the middle of dorsal margin, anterior and posteroventral overlap the largest. RV with (very) small marginal tubercles along anteroventral and posteroventral margins. External surface with ‘stretch marks’. A2 with natatory setae well-developed, short accompanying seta absent; male A2 with four-segmented endopodite and with t2 and t3 transformed into sexual bristles. Rpp and Lpp asymmetrical, but both with unusually short and broad first segments. Rpp first segment with V-shaped indention in dorsal margin, distally with large pointed hook; second segment rounded, bluntly pointed toward ventral side. Lpp with first segment with semi-parallel margins; second segment short and strongly curved, sickle-shaped and smoothly rounded. T1 with one long and hirsute seta next to the two a-setae. T2 without d2-seta. T3 without dp and d2 setae. CR with a short proximal seta in male and very long proximal seta in female. Hp generally rather narrow, with ls long, narrow and distally rounded; ms triangular, distally sharply pointed and almost as long as ls.

Differential diagnosis. Brasilocypria namiotkoi gen. et spec. nov. can be distinguished from most other species of Physocypria s.l. by the elongated valves in the male and the stretch marks present on the male Cp. Physocypria biwaensis and P. bullata , also have a pointed lobe ms on the Hp, but in B. namiotkoi gen. et spec. nov., the ms is not curved at the tip and the triangular and pointed end is shorter than in P. biwaensis and P. bullata . Physocypria capensis ( Sars, 1895) , P. kraepelini and Physocypria nipponica Okubo, 1990 also have a pointed end of the ms, however, this lobe in these species is more slender and less triangular than in the new species ( Table 3 ). The stretch marks present in the Cp surface of male of B. namiotkoi gen. et spec. nov. are a unique characteristic, which is not observed in other species from the same genus.

Material examined. Type locality: Amazon River floodplain, Castanho Lake ( AMA 80), in Eichhornia crassipes and Paspalum sp. Coordinates: 3°23′57′′ S, 60°13′27.8′′ W.

Type material: Holotype: A male, with soft parts dissected in glycerine in a sealed slide and with valves stored dry in a micropaleontological slide ( MZUSP 43178 ).

Allotype: A female, dissected and stored as the holotype ( MZUSP 43179 ).

Paratypes: One male carapace stored dry in a micropaleontological slide ( MZUSP 43180 ) .

Three female carapaces stored dry in micropaleontological slides ( MZUSP 43181, MZUSP 43182, MZUSP 43183).

Etymology: The species is named in honour of Prof. Tadeusz “Tadek” Namiotko (University of Gdansk, Poland), in recognition of his important contribution to the knowledge of ecology, morphology and systematics of non-marine ostracods, and with gratitude for years of friendship with KM.

Measurements of illustrated specimens. See Table 2 .

Description of male. Valves with suboval shape, with greatest height just in middle of valves. LVi ( Figs 34A, C–D ) with narrow calcified anterior and posterior inner lamella; an inwardly displaced inner list running along the anterior margin, ending in an internal anteroventral tooth; tubercle-sockets displaced along anteroventral and posteroventral margins.

RVi ( Figs 34B, E–F ) with narrow calcified anterior and posterior inner lamella and an inwardly displaced inner list along the anterior margin, disappearing in the anteroventral margin; strong marginal tubercles along the anteroventral and posteroventral margins, weakly along the middle of ventral margin.

CpRl ( Fig 34G ) with a suboval shape, with greatest height in middle; LV overlaps RV along all margins. CpD ( Fig 34H ) and CpV ( Fig 34I ) with a compressed shape, with greatest width in middle, external surface with shallow pits and setae and ‘stretch marks’ ( Fig 34J ).

Only the differences with the male of Brasilocypria pea gen. et spec. nov. are described here.

A1 (not illustrated) third segment with two apical setae: ventrally with one short seta almost reaching middle of fifth segment and dorsally with one short seta reaching middle of fourth segment. Sixth segment with one short hirsute seta (more than 5x length of terminal segment).

A2 (not illustrated) exopodite a small plate with two short setae and one long hirsute seta (reaching middle of second endopodal segment). First endopodal segment ventrally with aesthetasc Y (ca. 1/3 of length of segment). Second endopodal segment with aesthetasc y1 not seen. Terminal segment with one g-seta, ca. 1/2 length of y3.

Md-palp (not illustrated) with second segment with stout hirsute β-seta (ca. 1/2 of the length of the third segment).

T1 with protopodite ( Fig 35A ) and endopodite (asymmetrical prehensile palps) ( Figs 35B–C ). Protopodite apically with a group of 12 unequal and hirsute setae, two short smooth a-setae, one long and hirsute b-seta, one long and smooth d-seta, and one long and hirsute seta next to the two a-setae (2x length of d-seta). Rpp ( Fig 35B ) first segment with V-shaped dorsal margin, distally with large pointed hook; second segment rounded, bluntly pointed toward ventral side. Lpp ( Fig 35C ) with first segment with parallel margins; second segment short and strongly curved, smoothly rounded.

T2 (not illustrated) terminal segment with h3-seta slightly shorter than h1.

T3 (not illustrated) first endopodal segment with one hirsute dp-seta and one short and hirsute d1-seta (ca. 1/3 the length of dp).

CR ( Fig 35D ) well-developed and robust, with one short proximal seta (ca. 1/3 of ramus), subapically with one serrated claw, apically with one long serrated claw and one short and smooth seta.

Hp ( Fig 35E ) generally rather narrow, with ls long, narrow and distally rounded; ms triangular, distally sharply pointed and almost as long as ls.

Description of female. Only the differences with the male of Brasilocypria namiotkoi gen. et spec. nov. are described here.

LVi ( Figs 36A, C–D ) and RVi ( Figs 36B, E–F ) wider than male. RVi with tubercles in posteroventral and anteroventral margins, absent in middle of the ventral margin. CpRl ( Fig 36G ) with LV overlapping RV along all margins, except in dorsal side in front of middle. CpD ( Fig 36H ) and CpV ( Fig 36I ) with greatest width behind middle, external surface with shallow pits and setae, without ‘stretch marks’ ( Fig 36J ).

A1 (not illustrated) third segment with two apical setae: ventrally with one short seta almost reaching the tip of the fifth segment and dorsally with one short seta reaching the middle of the fifth segment.

A2 (not illustrated) exopodite with two short setae and one long hirsute seta (reaching tip of second endopodal segment). Third endopodal segment apically with three claws (G1, G2, G3) and three setae (z1, z2, z3).

T1 ( Fig 37A ) with protopodite apically with a group of 12 unequally and hirsute setae; two short a-setae, one short smooth b-seta, one long and smooth d-seta (more than 5x length of b-seta), and one long and hirsute seta next to the two a-setae (2x length of d-seta). Endopodite apically with one long and two short setae (one ca. 2/3 length of the long and one 1/2 length of the long).

T2 (not illustrated) first endopodal segment with one apical hirsute e-seta, reaching beyond middle of third endopodal segment. Third endopodal segment with one subapical hirsute g-seta, reaching beyond tip of the terminal segment. Terminal segment with hirsute h3-seta, slightly longer than h1.

CR ( Fig 37B ) well-developed and robust, with one long proximal seta (more than 2/3 of ramus), subapically with one serrated claw, apically with one long serrated claw and one short and hirsute seta.

Remarks. The sexual dimorphism in valve shape in this species is unusually large. Care was taken to evaluate all available specimens. No males were found with the present female morphology or vice versa, so that at this stage we consider both sexes as conspecific.

Ecology and distribution. Brasilocypria namiotkoi gen. et spec. nov. was recorded only from the Amazon River floodplain, associated with two different macrophytes. The water temperature was 33°C. The pH recorded was 6.4. The electrical conductivity value was 43.5 μS. cm-1 and the dissolved oxygen was 0.9 mg. L- 1 (see Table 1 ).

Figures

FIGURE 34. Brasilocypria namiotkoi gen. et spec. nov. ♁ from Amazon River floodplain, Castanho Lake (AMA 80). A. LVi (MZUSP 43178). B. RVi (MZUSP 43178). C. LVi, detail of posterior part (MZUSP 43178). D. LVi, detail of anterior part (MZUSP 43178). E. RVi, detail of anterior part (MZUSP 43178). F. RVi, detail of posterior part (MZUSP 43178). G. CpRl (MZUSP 43180). H. CpD (MZUSP 43180). I. CpV (MZUSP 43180). J. CpD, detail of anterior part showing the surface of Cp (MZUSP 43180). Scale bars: A–B, G–I = 250 μm; C–F = 100 μm; J = 50 μm. Arrow indicates anterior direction.

FIGURE 35. Brasilocypria namiotkoi gen. et spec. nov. ♁ from Amazon River floodplain, Castanho Lake (AMA 80). A. T1 (MZUSP 43178). B. Rpp (MZUSP 43178). C. Lpp (MZUSP 43178). D. CR (MZUSP 43178). E. Hp (MZUSP 43178). Scale bars: A–E = 50 μm.

FIGURE 36. Brasilocypria namiotkoi gen. et spec. nov. ♀ Amazon River floodplain, Castanho Lake (AMA 80). A. LVi (MZUSP 43179). B. RVi (MZUSP 43179). C. LVi, detail of posterior part (MZUSP 43179). D. LVi, detail of anterior part (MZUSP 43179). E. RVi, detail of anterior part (MZUSP 43179), arrow indicates piths fitting teeth in opposing valve. F. RVi, detail of posterior part (MZUSP 43179). G. CpRl (MZUSP 43181). H. CpD (MZUSP 43182). I. CpV (MZUSP 43183). J. CpD, detail of anterior part showing the surface of Cp (MZUSP 43182). Scale bars: A–B, G–I = 250 μm; C–F = 200 μm; J = 100 μm. A, B, G–I, Arrow indicates anterior direction.

FIGURE 37. Brasilocypria namiotkoi gen. et spec. nov. ♀Amazon River floodplain, Castanho Lake (AMA 80). A. T1 (MZUSP 43179). B. CR (MZUSP 43179). Scale bars: A–B = 50 μm.