Candobrasilopsis brasiliensis ( Sars, 1901 ) Higuti & Martens, 2012

Higuti, Janet & Martens, Koen, 2012, Description of a new genus and species of Candonopsini (Crustacea, Ostracoda, Candoninae) from the alluvial valley of the Upper Paraná River (Brazil, South America), European Journal of Taxonomy 33, pp. 1-31 : 18-28

publication ID	https://doi.org/ 10.5852/ejt.2012.33
publication LSID	lsid:zoobank.org:pub:85998904-3543-461B-A741-CC6959AA48DE
DOI	https://doi.org/10.5281/zenodo.3859034
persistent identifier	https://treatment.plazi.org/id/03A9D615-FFC7-FFF8-FE63-FA55CAFBFDA9
treatment provided by	Valdenar
scientific name	Candobrasilopsis brasiliensis ( Sars, 1901 )
status	comb. nov.

Treatment

Candobrasilopsis brasiliensis ( Sars, 1901) comb. nov.

Figs 7 View Fig C-D, 8-13

Candonopsis brasiliensis Sars, 1901: 45-46 .

Candonopsis brasiliensis – Würdig 1984: 439-447. — Martens & Behen 1994:14. — Higuti et al. 2007: 1935. — Higuti et al. 2009b: 664. — Higuti et al. 2010: 267. — Mormul et al. 2010: 189. Candonopsis brasiliensis incertae sedis – Karanovic & Datry 2009: 5.

Diagnosis

A species of the tribe Candonini , with elongated valves, greatest height well behind the middle; carapace in lateral view with dorsal margin straight over 2/3 of the length. Anterior calcified inner lamella in both valves broad; almost 1/5 of total length and with inner margin sinuous, not parallel to the valve margin. Base of right prehensile palp narrow and rounded, distal part curved, distal tip slightly expanded, set with two subequal lateral setae. Left prehensile palp larger and more elongated, with hook-like distal

part, distal tip not swollen. Hemipenis with triangular ls, bluntly pointed, bearing large and rounded proximo-dorsal expansion, and with rounded ms bearing a ventral, wart-like expansion.

Type material and type locality

Sars (1901: 46) wrote: “Only 2 female specimens of this form were secured. They were found in one of my aquaria prepared with mud from São Paulo ”. No detailed locality information is provided. Given de expansion of the city of São Paulo over the past 100 years, the actual locality from which the mud was collected has meanwhile almost certainly been destroyed.

Remark

Sars (1901) based his description and illustration (only a dorsal and left lateral view of a carapace) on 2 female specimens only. As females in this genus do not have the most specific characters which are in the hemipenis and prehensile palps of the male, we have decided not to rely on the type material to redescribe this species. Rather, we use new material from the Upper Paraná River, about 700 km WNW from São Paulo City.

Material used for the present redescription

See Table 1 View Table 1 for an overview of localities in the alluvial valley of the Upper Paraná River where this species was found.

Specimens are here used for illustrations and are also deposited in the museums indicated above. Eight ³³, with soft parts dissected in glycerine in a sealed slide and with valves stored dry ( MZUSP.28117, OC.3295, OC.3296, MZUSP.28120, MZUSP.28121, MZUSP.28122, MZUSP.28123, MZUSP.28124); four ³ carapaces stored dry in micropalaeontological slides ( MZUSP.28119, OC.3297, OC.3298, and MZUSP.28118). Three ♀♀, with soft parts dissected in glycerine in a sealed slide and with valves stored dry ( MZUSP.28125, OC.3299, OC.3300); three ♀ carapaces stored dry in micropalaeontological slides ( MZUSP.28127, MZUSP.28126, OC.3301 ).

Differential diagnosis

This species differs from the congeneric species ( C. rochai gen. nov. sp. nov.), by the shape of the valves, by rounded basal part of the right prehensile palp and by the large hemipenis with blunt tip and the ms with a ventral wart-like expansion.

Redescription of male

Valves ( Fig. 8A, B View Fig ) elongated, with greatest height situated well behind the middle (and bluntly pointed there), middle 2/3 of the dorsal margin straight and sloping towards the anterior margin; anterior margin rather narrowly and posterior rather broadly rounded. RV and LV of highly similar shape; anterior calcified inner lamella broadly rounded, posterior calcified inner lamella very narrow and almost disappearing towards the dorsal side; inner margin of anterior calcified inner lamella slightly sinuous in both valves.

Carapace in right lateral view ( Fig. 8C View Fig ) showing LV overlapping RV slightly on postero-dorsal and ventral sides; external surface of valves smooth.

In dorsal ( Fig. 8D View Fig ) and ventral ( Fig. 8E View Fig ) views, carapace lancet-shaped, bluntly pointed anteriorly, more broadly so posteriorly, greatest width situated well behind the middle.

A1 ( Fig. 9C View Fig ) with 5 terminal segments relatively elongated (L = at least 1.5 x basal width). Basal segment of A1 (= undivided protopodite) with 2 long sub-apical, ventral setae and two shorter setae on the dorsal side, of the latter one inserted at c mid-length, the other sub-apical. Second segment of basal part with one long (reaching beyond basis of fifth segment) dorso-subapical seta, no ventro-apical seta present. Third segment with one small sub-apical dorsal and ventral setae. Fourth and fifth segments with two longer dorso-apical and 1 shorter ventro-apical setae. Sixth segment with three longer dorsoapical and one shorter ventro-apical setae. Seventh (terminal segment) most elongate of all, slightly sinuous, bearing one short and two longer setae and one aesthetasc Ya, the latter shorter than the shorter seta.

A2 ( Fig. 9A, B View Fig ) with basal segment broad, wide and relatively long, basally with 2 unequal setae, one relatively long and slender, the other very short and broad, both hirsute; apically with a ventral seta. Remnant of exopod consisting of a short plate, one long and two very short setae. Endopod consisting of 4 segments (penultimate segment divided). First endopodal segment long, carrying one long aesthetasc Y on the ventro-basal side, and one long and one short ventro-apical setae. Second endopodal segment shorter and smaller, but still rectangular with one ventral aesthetasc y1 inserted about mid length, 3 t-setae, with t1 a long, hirsute setae, t2 and t3 modified in the male-bristles; this segment dorsoapically with 3 short setae of unequal length. Third endopodal segment with apical chaetotaxy sexually dimorphic, with z1 and z3 being short setae, z2 being modified into a long claw; G2 a long claw, G1 a long seta and G3 a short setae, aesthetasc y2 short and ventro-apically inserted. Terminal (4 th) segment ( Fig. 9B View Fig ) small, distally with claws GM (long) and Gm (short), aesthetasc y3 with its companion seta, fused at the basis and with seta almost twice as long as aesthetasc, and seta g, clearly longer than y3.

Md with coxa ( Fig. 9F View Fig ) relatively elongated, distally set with a series of strong teeth. Md-palp ( Fig. 9D View Fig ) consisting of 4 segments. Basal segment dorsally carrying the respiratory plate (not shown), ventroapically with 2 long hirsute setae (s1 & s2) and the alpha seta, the latter proximally with a broad base and a flagellum-like, distal part. Second segment dorso-apically with 2 setae of unequal length, ventrobasally with a short, stout and hirsute seta and ventro-apically with a group of 5 setae: 3 long and hirsute setae (similar to the two s-setae of the previous segment), a shorter, less hirsute seta and the short and hirsute beta-seta. Third segment with a group of 3 dorso-subapical setae, the latter smooth, a central apical group of two setae, one of which being the gamma seta and ventro-apical group of 4 unequal setae. Terminal segment rectangular, apically set with two large claws and an uncertain number of smaller setae.

Mx1 ( Fig. 9E View Fig ) with a basal (basipodite) part carrying a large respiratory plate (exopodite), 3 endites and a two-segmented palp (endopodite). Respiratory plate ( Fig. 10G View Fig ) elongated, carrying more than 20 respiratory rays, some quite short, others long. Palp with first segment carrying 3+1 apical setae; terminal segment short and broad, carrying 2 longer claws and c 3 short setae. Chaetotaxy of three endites impossible to determine. Sideways directed bristles near first endite long and stout.

T1 (sometimes called Mx2 – Fig. 10A View Fig ) consisting of basal part (basipodite), carrying respiratory plates (not shown), a palp (modified to prehensile palp in males) and an exopodite (?) distally set with 14-15 setae of different morphology and length. Basal plate set with one long and stout ‘d’-seta, a shorter and more slender ‘b’-seta and two ‘a’-setae of unequal length. Prehensile palps ( Fig. 10D, E View Fig ) onesegmented, distally hook-like and set with two unequal, sub-apical setae; palps slightly asymmetrical, Rpp ( Fig. 10D View Fig ) slightly smaller than Lpp, distal part of apical hook slightly swollen in Lpp, not at all in Rpp.

T2 (walking limb – Fig. 10F View Fig ) with 4-segmented endopodite (penultimate segment divided) and elongated. First segment with long seta d1. Knee-segment devoid of seta d2. First segment of endopod especially elongated, with short ventro-apical seta (e). Second segment also with one short ventro-apical seta (f). Third segment with two ventro-apical setae, one short, one slightly longer. Terminal segment with one short apical and one short sub-apical seta and a long apical claw.

T3 (cleaning limb – Fig. 10C View Fig ) as typical of the family. First segment with three long setae, one medial (d1), one subapical (d2) and one apical (dp). Second segment with one subapical seta (e). Third segment with one long subapical seta (f), Penultimate segment with one short and curved subapical seta (g). Terminal segment well-separated from penultimate segment and carrying three setae: one long and reflexed (h3) and two side-ways directed (h1 & h2), the latter subequal.

Caudal ramus (furca – Fig. 10H View Fig ) with stout ramus and two stout apical claws. Proximal setae missing, distal seta a small spine. Attachment of caudal ramus ( Fig. 10B View Fig ) long and stout, distally bifurcated and with additional lateral branch before mid-length. Length ratio ramus/largest claw = 1.64.

Hemipenis ( Fig. 7C View Fig ) large, with medial shield rounded and with additional ventral protuberance, lateral shield bluntly pointed, triangular and with rounded, proximo-dorsal expansion; labyrinth short and stout, postlabyrinthal spermiductus narrow and straight, without additional coils, but with a weak bent at the most distal part.

Zenker organ ( Fig. 7D View Fig ) short and broad, with ca. 5 spinous whirls.

Redescription of female

Valves ( Fig. 8F, G View Fig ) and Cp ( Fig. 8H View Fig ) in lateral view similar to those in the male; valves in inner view slightly more elongated and less high than in the male. Cp in D and V views ( Fig. 8I, J View Fig ) slightly more slender than in the male.

Soft parts ( Figs 11 View Fig C-F, 12A, B, D-F) largely as in the male, but with sexually dimorphic A2 and T1.

A2 ( Fig. 11A, B View Fig ) with setae t1-4 setae like, not transformed; z1-3 short and slender setae. Claws G1, G2, G3 and GM all reaching to about the same point.

T1 ( Fig. 12C View Fig ) with basal part as in the male. Endopod a broad palp, with two short and one long distal setae.

Caudal ramus: length ratio ramus/largest claw = 1.61.

Measurements

See Table 3.

Ecology

Together, both species have been found in 29 localities, in a total of 48 localities sampled in the alluvial valley of the Upper Paraná River, they occurred sympatrically in only 11 localities.

Candobrasilopsis rochai gen. nov. sp. nov. occurred in 17 localities in the alluvial valley. The pH ranged between 5.1 and 6.6, electrical conductivity between 13.2 and 66.9 µS cm-1 and dissolved oxygen between 1.2 and 8.6 mg L-1.

Candobrasilopsis brasiliensis comb. nov. was found in 26 localities, with pH values ranging between 4.7 and 6.5, electrical conductivity between 23.6 and 114.9 µS cm-1 and dissolved oxygen between 0.6 and 13.3 mg L-1.

These species were predominant in several types of substrates as sediment (named littoral in Table 1 View Table 1 ) and different species of floating macrophytes ( Eichhornia crassipes , Pistia stratiotes , Hydrocotyle ranunculoides and Salvinia spp.) in different habitats (lakes, channels and rivers) ( Table 1 View Table 1 ).

Remarks

As some small differences in hemipenis morphology between two different populations of this species were detected, we dissected a longer series of males from 3 populations and illustrated both hemipenes of each individual ( Fig. 13 View Fig ). It is clear that indeed some variability exists, i.e. in the size of the proximodorsal expansion of the ls, as well as in the ventral expansion of the ms. Some of this variability might be a result of different positions of these organs between cover slip and glass slide. Therefore, we deem all of these populations to be conspecific.