Benincandona trapezoides, Hotèkpo & Schön & Martens, 2024

Hotèkpo, Sourou Joseph, Schön, Isa & Martens, Koen, 2024, An endemic species flock of Candonidae Kaufmann, 1900 (Crustacea, Ostracoda) from wells in Benin (Africa), with the description of a new subfamily, a new genus and five new species, Zootaxa 5503 (1), pp. 1-72 : 51-63

publication ID	https://doi.org/ 10.11646/zootaxa.5503.1.1
publication LSID	lsid:zoobank.org:pub:7385E4AA-D7AD-4E79-A05C-684319E0843B
persistent identifier	https://treatment.plazi.org/id/D8C20638-F2AA-4F8D-A762-31CB4CB6C241
taxon LSID	lsid:zoobank.org:act:D8C20638-F2AA-4F8D-A762-31CB4CB6C241
treatment provided by	Plazi
scientific name	Benincandona trapezoides
status	gen. et spec. nov.

Treatment

Benincandona trapezoides gen. et spec. nov. Hotèkpo & Martens urn:lsid:zoobank.org:act:D8C20638-F2AA-4F8D-A762-31CB4CB6C241

( Figures 32– 39 View FIGURE 32 View FIGURE 33 View FIGURE 34 View FIGURE 35 View FIGURE 36 View FIGURE 37 View FIGURE 38 View FIGURE 39 , 41O–R View FIGURE 41 )

Etymology

The species is named after the shape of the carapace in lateral view, which is largely trapezoid.

Diagnosis

CpRl relatively high (L/H = 2.0), dorsal margin straight over circa one third of the entire length, with greatest height in the middle; LV dorsally extending beyond RV over the entire length of the straight part of the dorsal margin, anterior margin broadly rounded, posterior margin running straight towards the ventral side, the latter almost straight, valve surface set with ridges in most of the central part. CpD and CpV relatively wide, with greatest width in the middle and lateral sides straight in the middle, anterior extremity sharply and posterior side more bluntly pointed. A2 with seta X long, reaching well beyond the tip of the aesthetasc Y, the latter distally not bifurcated. Second palp segment of Mx1 with L c. 1.5x basal W. T3 with seta d2 absent. Hp with ls and ms with overlapping positions, lobe ls broad and rounded, extending beyond lobe ms with more than half of its length.

Type material

Holotype

1 ♂, with soft parts dissected in glycerine in a sealed slide, and with valves stored dry ( INV.159263).

Allotype

1 ♀, dissected and stored as the male ( INV.159264).

Paratypes

2 ♂♂ dissected and stored as the holotype ( INV.159265, INV.159266) ; 9 ♀♀ dissected and stored as the male ( INV.159267, INV.159268, INV.159269, INV.159270, INV.159271, INV.159272, INV.159273, INV.159274, INV.159275) ; 3 ♂♂ carapaces stored dry in micropalaeontological slides ( INV.159276, INV.159277, INV.159278) ; 1 ♀ carapace stored dry in micropalaeontological slide ( INV.159279) .

Type locality

Benin, Borgou Department, Parakou District , town Bapérou located in the Okpara catchment area (tributary of the Ouémé catchment area) , coordinates: 9°16.380’N, 2°34.913’ E, Leg.: S.J. Hotèkpo and M. Lagnika collected on 05 November 2022 (Locality code A 1 in Tables 1 and 2).

Description of male

CpRl ( Figure 32A–C View FIGURE 32 ) with trapezoidal shape (L/H ratio=2.0); dorsal margin straight in the middle 1/3, with greatest height in the middle, anterior margin broadly rounded, posterior margin running straight towards ventral margin, the latter almost straight; LV overlapping RV along anterior, ventral and posterior sides, dorsally strongly overlapping RV along the entire length of the straight part; valve surface set with ridges in the middle part of the valves ( Figure 32H–J View FIGURE 32 ). CpD and CpV ( Figure 32G, K View FIGURE 32 ) relatively wide, pointed sharply anteriorly and bluntly posteriorly, greatest width in the middle, lateral margins straight in the middle part.

LVi ( Figure 33A, C, D, G View FIGURE 33 ) elongated and sub-triangular, dorsal margin straight in the middle third, with greatest height in the middle, anterior margin broadly rounded; posterior margin sloping towards ventral margin, the latter almost straight; ventral il without antero-ventral tooth. CMS ( Figure 33G View FIGURE 33 ) as in the type species.

RVi ( Figure 33B, E, F, H View FIGURE 33 ) elongated, with dorsal margin straight in the middle third and with greatest height in the middle, anterior margin broadly rounded; posterior margin sloping towards ventral margin, the latter almost straight; ventral il without antero-ventral tooth. CMS ( Figure 33H View FIGURE 33 ) as in the type species.

A1 ( Figure 35B View FIGURE 35 ) with seven segments, one basal and six distal. Basal segment with two sub-apical, ventral setae, one long and one shorter, the latter about half of the length of the longer one, and two shorter setae on the mid-dorsal side (one not illustrated here), situated some distance from each other. First distal segment about 2.5 times as long as the basal width, with one short dorso-subapical seta. Second distal segment with about the same length/width ratio as the previous segment, set with one short dorso-apical seta. Third distal segment also with about the same length/width ratio, carrying one short apical setae on each side. Fourth distal segment about three times as long as wide, and set with one short ventro-apical seta and two long dorso-apical. Fifth distal segment about five time as long as wide, with two long dorso-apical setae and one short ventro-apical seta clearly exceeding the next segment. Sixth distal segment narrow, at least five times as long as wide, with four apical structures: one aesthetasc Ya of intermediate length, two long and one short setae (about one third the length of Ya).

A2 ( Figure 35A View FIGURE 35 ) with basal segment (first protopodite) broad and rounded, mid-ventrally with one seta of medium length, subapically with two setae of unequal length, proximal one c. four times the length of the more apical one. Second segment (second protopodite) large and c. twice as long as basal width, set with one long ventro-subapical seta X. No remnant of exopodite visible. Endopodite consisting of four segments (penultimate segment divided). First endopodal segment large and stout, five times as long as basal width, carrying one long and narrow mid-ventral aesthetasc Y, and two ventro-apical setae, one short and one large and stout, hirsute in its distal 4/5. Second endopodal segment (segment 2A) c. twice as long as wide, carrying one stout dorso-apical plumose seta and three t-setae; seta t1 long, narrow and plumose, accompanied by a slender aesthetasc y1; t2 and t3 setae hyper-developed into male bristles, t2 ventro-apical, t3 centro-apical. Third endopodal segment (segment 2B) smaller than previous segment and about 1.5x as long as wide, set with a complex (and sexually dimorphic) apical chaetotaxy ( Figure 40 View FIGURE 40 ): ventro-apically with one slender aesthetasc y2 and claw G3 transformed into one short seta about equal length as y2; centrally with one short plumose seta z3; dorso-apically, z1 claw-like about 1.5x as long as penultimate segment. Claw G2 and G1 about 2.5 times as long as z1; seta z2 transformed into long claw, reaching tip of G1. Fourth, terminal, endopodal segment with one long claw (Gm), one short claw (GM), a long aesthetasc y3 with shorter accompanying seta, with fused part short, and a seta g (slightly exceeding tip of aesthetasc y3).

MdCoxa ( Figure 35C View FIGURE 35 ) elongated, proximally sharply pointed, medially widened, distally with an obliquely widened end, set with a series (6–7) of strong teeth, interspaced with setae; subapically with a short seta.

MdPalp ( Figure 36C View FIGURE 36 ) with four segments. Basal segment ventro-subapically carrying two hirsute setae (S1 & S2), S1 long, reaching tip of terminal segment and S2 short and stout, length about one fourth of the length of S1; in between with the short flagellum-like alpha seta (thin and as short as S2), and one smooth and medium size (slightly shorter than S1) more proximal seta. Second segment of sub-triangular shape, dorso-apically with two setae of unequal length; ventro-apically with a group of four long setae, one of these being the beta-seta. Third segment with two unequal dorso-subapical setae, two mid-dorsal setae, one of which being the gamma seta, and ventro-apically with two setae of sub-equal length. Terminal segment sub-rectangular, apically set with one large claw, fused with the segment over its entire distal margin, accompanied by one smooth lateral seta on each side, tips slightly shorter than the fused claw.

Mx1 ( Figure 36A, B View FIGURE 36 ) with a basal (protopodite) part carrying a large respiratory plate (exopodite), three endites and a two-segmented palp (endopodite). Respiratory plate ( Figure 36A View FIGURE 36 ) elongated, carrying c. 18 plumose respiratory rays, two short distal setae and a group of shorter proximal setae (not illustrated). Palp ( Figure 36B View FIGURE 36 ) with first segment carrying four long dorso-apical setae; terminal segment short and rectangular, carrying four distal setae, some slightly claw-like; chaetotaxy of three endites incompletely illustrated: third endite with two strong teeth carrying lateral spines (Zahnborsten), basally with one lateral seta; sideways directed bristles near base of first endite, one long and one short, c. half the length of the long one.

T1 ( Figure 39A, B View FIGURE 39 ) consisting of basal part (protopodite), carrying respiratory plates (exopodites not shown). Protopodite ( Figure 39B View FIGURE 39 ) distally set with almost 10 plumose setae of different morphology and length; more proximally set with d, d’ and b setae. Prehensile palps asymmetrical Rpp ( Figure 39B View FIGURE 39 ) slightly more swollen than Lpp ( Figure 39A View FIGURE 39 ); one-segmented, distally sigmoid hook-like, both palps set with a short sensory organ and proximally with two subequal setae.

T2 ( Figure 37A View FIGURE 37 ) with 4-segmented endopodite (penultimate segment divided), generally elongated. First basal segment without setae d1 and d2. First segment of endopodite elongated (length more than four times basal width), without seta. Second segment (segment 2A) with length c. 4x width with one short ventro-apical seta f. Third segment (segment 2B) about the same length/width ratio as the previous segment, set with one ventro-subapical seta g. Terminal segment (segment 3) almost as long as width, apically with two short setae (h1 and h3), h1 (ventral) and twice the length of h3 (dorsal), and a long and slender claw (h2), distally set with short setulae.

T3 ( Figure 37B View FIGURE 37 ) with first segment carrying only one subapical seta d1, of intermediate length. Second (knee-) segment without seta d2. Third segment about four times as long as wide, not carrying any seta. Fourth segment narrower and at least 8x basal width and carrying one short subapical seta g. Terminal segment well-separated from penultimate segment, about twice as long as basal width and carrying three setae: one long and reflexed (h3), almost reaching knee-segment and two ventrally directed and curved setae h1 and h2, the later slightly exceeding of the former.

CR ( Figure 37C View FIGURE 37 ) with stout ramus; claw Ga well-developed, stout with length slightly exceeding half the length of ramus, setae Sp, Sa and claw Gp reduced to small setae; seta Sp situated about at one-fifth length of ramus from distal end, Sa dorso-subapical and Gp ventro-subapical.

CRAtt ( Figure 37D View FIGURE 37 ) long and stout, distally bifurcated, subapically with additional lateral branch.

Hp ( Figure 38B–D View FIGURE 38 ) with robust and rounded lobe ls, reaching well beyond the asymmetrically rounded lobe ms, both lobes overlapping, not diverging; lobe ‘h’ shorter and sub-rectangular; internal anatomy ( Figure 38C, D View FIGURE 38 ) with postlabyrinthal spermiduct with one circular coil.

Zenker organ ( Figure 38A View FIGURE 38 ) elongated with c. seven spinous whirls.

Description of female

Cp and valves ( Figures 32D–F View FIGURE 32 , 34A–H View FIGURE 34 ) as in the male, without obvious sexual dimorphism.

Limbs ( Figure 39C–E View FIGURE 39 ) largely as in the male, but with sexually dimorphic A2 and T1.

A2 ( Figure 39C View FIGURE 39 ) with second endopodal segment undivided, with t1-seta (long, narrow and plumose) and t2- seta (thin and smooth); apical chaetotaxy ( Figure 40 View FIGURE 40 ) with z1claw-like, z2 and z3 being both setae, z1 about 3x as long as z2, and z3 slightly shorter than z2; claws G1, G2, G3 and GM all reaching about the same point; seta g and aesthetasc y3 as in the male and the tip of Gm slightly longer than the tip of y3. Small claw Gm in female homologous to large claw in the male.

T1 ( Figure 39D View FIGURE 39 ) with basal part with c. 10 distal setae of unequal length and morphology, setae d and b present, with long additional seta (d’) present close to seta d; respiratory plate represented by two long rays. Endopodite set with a short and narrow palp, with three subequal but short apical setae (h1–h3).

Measurements: See Table 3.

Differential Diagnosis: See Table 4.

Ecology and distribution

This subterranean species was thus far only found in its type locality.

Other candonid species from the wells in Benin

( Figures 42 View FIGURE 42 , 43 A View FIGURE 43 – AD)

Thirty further candonid species, in addition to the five new species described above, have been found in the samples from the wells in Benin. Most of these are also (sub-) triangular in lateral view, with strong ( Figures 42 View FIGURE 42 /43E, N, AB) or weak ( Figures 42 View FIGURE 42 /43K, M, Z) external lateral ridges; others have different shapes ( Figures 42 View FIGURE 42 /43F, G, O, V, AC). Some species ( Figure 42A, D, N View FIGURE 42 ) are much larger than most, and some are much smaller ( Figures 42 View FIGURE 42 /43O, X, AA, AD). Based on preliminary analyses of the soft parts of these species, it is at present most likely that all of these species belong to Benincandona Hotèkpo & Martens , but this requires further confirmation.