Triangocypretta nates, Ferreira & Higuti & Martens, 2023

Ferreira, Vitor Góis, Higuti, Janet & Martens, Koen, 2023, On a new genus and four new species of the subfamily Cyprettinae (Crustacea, Ostracoda) from Brazilian floodplains, Zootaxa 5343 (5), pp. 401-438 : 425-433

publication ID	https://doi.org/ 10.11646/zootaxa.5343.5.1
publication LSID	lsid:zoobank.org:pub:24E92041-4F5C-42E2-B7A3-401BEA46D2C8
DOI	https://doi.org/10.5281/zenodo.8345971
persistent identifier	https://treatment.plazi.org/id/CDE63125-93D9-4B35-9399-7052A0A5FE47
taxon LSID	lsid:zoobank.org:act:CDE63125-93D9-4B35-9399-7052A0A5FE47
treatment provided by	Plazi
scientific name	Triangocypretta nates
status	gen. et spec. nov.

Treatment

Triangocypretta nates View in CoL gen. et spec. nov.

( Figs. 14–17 View FIGURE 14 View FIGURE 15 View FIGURE 16 View FIGURE 17 , 18G–H View FIGURE 18 )

urn:lsid:zoobank.org:act:CDE63125-93D9-4B35-9399-7052A0A5FE47

2017a Cypretta sp. 4 n. sp. Higuti et al.: p. e120, Table 2 View TABLE 2 .

2017 Cypretta n.sp. 2 Pereira et al.: p. 327, Table 2 View TABLE 2 .

Diagnosis

CpD with posterior margin more broadly rounded than anterior margin; Cp surface with few setae and shallow pits; CpLl with arched dorsal margin; RVi and LVi anteriorly both with ca. 13 septa; RV overlapping LV along the anterior, dorsal, and ventral margins; at the posterior margin, both LV and RV valve inwardly curved; T2 with d 1 half the length of d 2.

Type locality

Brazil • Araguaia River floodplain. Crixas Lake III (ARA52), in the roots of Eichhornia crassipes , in the Araguaia River floodplain. Leg. JH & KM, Collected on March 9 th, 2012. Coordinates: 13°21’52.6”S, 50°37’20.9”W.

Type material

Holotype: A female with soft parts dissected in glycerin in a sealed slide and valves stored dry in a micropaleontological slide (MZUSP 44404).

Paratypes: One female specimen dissected and stored as the holotype (MZUSP 44405). Five female specimens with valves stored dry in micropaleontological slides (MZUSP 44406, MZUSP 44407, MZUSP 44408, MZUSP 44409 and MZUSP 44410).

Other material examined

Brazil • Amazon River floodplain—Poraquequara IV Lake (AMA87). Leg. JH, collected on 18.05. 2012 in the following plants: Eichhornia crassipes , Salvinia auriculata , Pistia sp. Coordinates: 03°02’20.7”S, 59°47’54.0”W. One female specimen dissected and stored as the holotype (MZUSP 44411), and a female with valves stored dry in a micropaleontological slide (MZUSP44412), five female specimens with carapaces stored dry in micropaleontological slides (MZUSP 44413, MZUSP 44414, MZUSP 44415, MZUSP 44416 and MZUSP 44417).

Etymology

This species was named after the characteristic posterior margin resembling “buttocks” (“nates” in Latin).

Other localities

Triangocypretta nates gen. et spec. nov. occurred in the Amazon and Paraná river floodplains, frequently in lentic, but also in one lotic, environments (See Table 2 View TABLE 2 ).

Measurements

See Table 1 View TABLE 1

Description

LVi ( Figs. 14A, C View FIGURE 14 , 18G View FIGURE 18 ) with dorsal margin rounded and less arched, of sub-triangular shape only, greatest height situated in the middle; calcified inner lamella wide along anterior margin and narrow along ventral and posterior margins; anteriorly with incomplete inner list (running halfway up the anterior margin); and with inner margin of calcified inner lamella fortified by an inner list; ca. 13 well-developed septa along anterior margin.

RVi ( Figs. 14B, D View FIGURE 14 , 18H View FIGURE 18 ) with similar shape as LVi, but with posterior calcified inner lamella somewhat wider; with a submarginal groove along ventral margin; and with ca. 13 anterior septa.

CpLl (14E) with a sub-triangular shape; dorsally rounded, with greatest height in the middle region; external surface ( Fig. 14H View FIGURE 14 ) set with a few setae and very shallow pits; RV overlapping LV along anterior and dorsal margins. CpD and CpV ( Figs. 14F, G View FIGURE 14 ) broad, with oval shape, W ca. 3/4 of L, posterior margins with LV and RV bending inwardly. CpV with RV overlapping LV on all sides, especially in the middle region with a flap.

A1 ( Fig. 15A View FIGURE 15 ), consisting of seven segments. First segment with three setae (two unequal long ventral setae and a shorter mid-dorsal seta); Wouters organ not seen. Second segment with one dorsal seta (not reaching middle of third segment); Rome organ not seen. Third segment with one short (dorsal) seta and one short (ventral) (ca. 2/3 length of dorsal one). Fourth segment with two unequal but short ventro-apical setae and two long dorso-apical setae. Fifth segment with two unequal but short ventro-apical setae (longer one reaching beyond middle of terminal segment, and other slightly shorter) and two long dorso-apical setae. Sixth segment with four long apical setae, and a short α seta reaching beyond the tip of terminal segment. Terminal segment apically carrying one long aesthetasc y a, one medium length seta (with more than half length of y a) and two long setae.

A2 ( Figs. 15B, C View FIGURE 15 ) composed of six segments (two-segmented protopodite, one-segmented exopodite and threesegmented endopodite). Protopodite carrying three ventral setae, two mid-ventral (unequally with medium length) and one long and hirsute apical setae. Exopodite consisting of a short plate with three setae, two unequal but short, and one medium length (as long as first endopodite). First endopodal segment with one mid-ventral aesthetasc Y (ca. half-length of segment); one medium length and hirsute apical seta with length of segment; and five long hirsute natatory setae (reaching tips of z setae) and one medium-long seta accompanying natatory setae (almost reaching tip of second endopodal segment). Second endopodal segment with one long and one medium length mid-dorsal setae (medium length one with 2/3 of long one); and a group of four mid-ventral t-setae (three equally medium length and one short setae); three equally long z setae (z 1, z 2 and z 3); and three long claws (G 1 slightly shorter one; G 2 and G 3 equally long); and one short aesthetasc y 2.Terminal segment ( Fig. 15C View FIGURE 15 ) with one long claw G M, and one medium length claw G m; one aesthetasc y 3 and accompanying seta (slightly longer than y 3); seta g not observed.

MdCoxa ( Fig. 16A View FIGURE 16 ) consisting of an elongated plate with ca. seven apical teeth intercalated with short setae; one hirsute sub-apical seta on dorsal margin. MdPalp ( Figs. 16C, D View FIGURE 16 ) consisting of four segments. First segment with long setae S 1 and S 2; one long smooth seta and a short and narrow smooth α-seta. Second segment ventrally with a cone-shaped and hirsute β seta, two long and one medium length smooth setae, and one medium length and hirsute seta; dorsally with a group of two unequal but long setae and one medium length seta (ca. half-length of long ones). Third segment dorsally with a group of four equally long setae; ventrally with one medium length seta and one short seta (ca. 1/5 length of medium length one); apically with one long setae, two medium length setae and one medium length cone-shaped, smooth γ-seta. Last segment ( Fig. 16D View FIGURE 16 ) with three claws and three setae.

Mx1 ( Fig. 16B View FIGURE 16 ) with a respiratory plate (not illustrated), three endites (chaetotaxy not fully illustrated) and a two-segmented palp. First palp segment with a lateral seta of medium length, and six unequally long apical setae. Second palp segment rectangular, ca. 1.5x as long as basal width; apically with one long claw, and two long and three shorter setae. Third endite with one very long lateral seta and two smooth claws (Zahnborsten). First endite with two subequal but long “sideways directed bristles”. Two basal setae, subequal but long.

T1 ( Figs. 17A, B View FIGURE 17 ) composed of an endopodite and a protopodite. Endopodite with three apical hirsute setae, one short, one of medium length and one long. Protopodite with two equally short a-setae; one short d seta, b seta missing; 10 apical hirsute and unequally short setae and three equally short sub-apical setae.

T2 ( Fig. 17C View FIGURE 17 ) composed of five segments. First segment with short seta d 1. Second segment with seta d 2 twice the length of d 1. Third segment with seta e of medium length ventrally serrated. Fourth segment divided in a and b segment; a segment with long apical f seta ventrally serrated and reaching well beyond edge of terminal segment; b segment apically with a short g seta (almost reaching tip of terminal segment). Terminal segment apically with two short setae h 1 and h 3; and a long claw h 2, weakly serrated in its distal part.

T3 ( Figs. 17D, E View FIGURE 17 ) composed of four segments. First segment with three setae of medium length, slightly unequal (d 1, d 2 and d p; almost as long as second segment). Second segment with a medium length apical e seta (reaching halfway along third segment). Third segment with short sub-apical f seta. Third segment fused with fourth segment, forming a pincer-shaped organ, ( Fig. 17E View FIGURE 17 ); with a short seta h 1, longer h 2 claw; and a medium length and hirsute h 3 seta.

CR ( Fig. 17F View FIGURE 17 ) with long but narrow and weak ramus, two long claws (one apical G a, shorter than ramus and one sub-apical G p with less than half length of G a); one long seta S p on ventral margin, apical seta S a absent.

CR attachment ( Fig. 17G View FIGURE 17 ) a single short and narrow rod, without bifurcation.

Remarks

We dissected individuals from Amazon and Araguaia floodplains, and both valves and soft parts morphology were similar. A few individuals were identified (through stereomicroscope) from Amambaí River, a tributary of Paraná River, however their valves were decalcified and observation with SEM was not possible.

Differential diagnosis

Triangocypretta nates gen. et spec. nov. has far less valve ornamentation and has much smoother valves than in the other three species. In comparison with the other species described here, the anterior marginal septa are most visible in the SEM images. It can be distinguished from the other species by the posterior margins of the two valves bending inwardly in dorsal view, giving an image of “buttocks”, but in a more prominent way than in Triangocypretta angustus gen. et spec. nov. Compared with Triangocypretta labiata gen. et spec. nov., Triangocypretta nates gen. et spec. nov. has a less pointed anterior margin, with the anterior margin more broadly rounded. The soft part morphology is quite similar with the other three new species described here, the only differences are noticed in the MdPalp, T2 and CR (see differential diagnosis above).

The d 1 seta on the T2 has about half the length of seta d 2, as in Triangocypretta angustus gen. et spec. nov. In T. hirsuta , setae d 1 and d 2 are of subequal length while in T. labiata seta d 1 is slightly shorter than d 1.

The G a claw on the CR has almost the same length as the main branch, similar with what is observed in the other three species. However, the G p is half the length of G a, while in T. hirsuta , T. labiata and T. nates it varies around 3/4 the length of G a.

Ecology

This species was recorded in a narrow range of environmental variables: temperature range was 20.6–31.5ºC; pH range was from 6.6–9.7; electrical conductivity was 29.8–54.4 μS. cm-1; dissolved oxygen range was 1.4–8.0 mg. L- 1 (see Table 2 View TABLE 2 , not all localities included).