Chirocephalus sanhadjaensis, Boumendjel & Rabet & Amarouayache, 2018

Boumendjel, Lylia, Rabet, Nicolas & Amarouayache, Mounia, 2018, Chirocephalus sanhadjaensis sp. nov., a new chirocephalid species (Branchiopoda: Anostraca) from Numidia (Algeria), Zootaxa 4526 (3), pp. 381-391 : 382-386

Chirocephalus sanhadjaensis sp. nov.

( Figs. 3 , 4 , 5 , 6 )

Etymology. The specific epithet “ sanhadjaensis ” refers to the Guerbes-Sanhadja wetlands complex of international importance (Ramsar 2001) where the Ain-Magroun and Belkroun pools are situated.

Type locality. Ain-Magroun, a temporary freshwater pond (coordinates: 36°50'20.99" N, 7°17'01.17" E, altitude 19 m a.s.l) ( Fig. 1 ). The pond is located in a meadow in the municipality of Ben Azzouz (Skikda Province, Northeastern Algeria) and is part of the Guerbes-Sanhadja wetlands complex. The pool has an oval shape and an area of about 1000 m 2, with a maximum depth of 0.5 m ( Fig. 2A ), and with some humid depressions in its periphery. It generally inundates in January or February and dries out in April. During our sampling in January 2015 the pH was of 7.13, water conductivity 154 µS/cm and temperature 9.4°C.

Chirocephalus sanhadjaensis appears to be restricted to the type locality and two small temporary pools in Belkroun (Ben Azzouz, Province of Skikda) located about 10 km east of Ain-Magroun pond (36°51'59.13"N, 7°23'37.35"E, altitude 6 m a.s.l.). These pools are artificial water holes for livestock watering with an area of about 16 m 2 and a maximum depth of about 2.5 m. During our sampling in December 2017, pH was of 7.15, conductivity of 262 µS/cm and water temperature of 10.9°C ( Fig. 2B ). The distribution of this species seems to be limited to the Guerbes-Sanhadja wetland complex, where agricultural activities are important.

Type material. Holotype. Mature male of 17.8 mm total length; Algeria: Skikda Province: Ain-Magroun temporary pond; 11 January 2015; S. Ghaouaci leg; stored in 96% ethanol after formalin fixation (MNHN-IU- 2017-2317).

Allotype. Mature female of 16.8 mm total length: same data as the holotype (MNHN-IU- 2017-2318) . Paratypes: Two males of 16 and 17.6 mm total length (MNHN-IU- 2017-2319); same data as holotype. Two females of 12 and 12.8 mm total length (MNHN-IU- 2017-2320); Algeria: Skikda Province: Belkroun; 20 December 2017; M. Amarouayache leg ; stored in ethanol 96% after formalin fixation. Description. Male. Living specimens have a transparent to greenish colour with a vermillion furcae.

First antennae filiform, with apical setae, with a length 0.7x of the second antenna proximal antennomere.

Second antennae ( Fig. 3C ) proximal antennomere curved medially, bearing an apophysis total length ~1.1x distal antennomere. Apophysis subconic, digitiform; apex with denticles; total length ~0.25x of the proximal antennomere. Second antennae distal antennomere with a proximal, medially directed, ~30° bend, apically truncated, and bearing a proximedial projection and a spiniform projection, just distal to the proximedial projection ( Fig. 3D ). Proximedial projection lobiform, distal surface bearing scattered denticles or apically truncated spinulae; total length ~0.2x article length. Antennal appendage ( Fig. 3A ) total length 0.6x second antenna. Basal lamella (ventral lamella) triangular, apex elongate, with a small dorsal carina. Basal lamella margins bearing small, evenly distributed papillae, with the medial margin provided with three rows of papillae. Lateral margin papillae each with an apical denticle ( Fig. 3B ). Antennal appendage dorsal lamella length 1.7x basal lamella, serrate in the distal half with medial and lateral margins bearing subtriangular papillae (larger medially) diminishing in size distally; apex acute. Medial papillae with posterior margin edged in short setae.

Labrum. Distal lobe rounded, 0.5 x of length exceeding the distal margin of the labrum.

Mandibles asymmetrical, right mandible molar surface with two posterio-apical acute spines, equal in length; molar surface of left mandible bearing a row of eight robust teeth on the lateral outer margin.

Maxilla I. Typical for the genus ( Cottarelli et al. 2010; 2017). Setae aciculate and straight; there is also a posterior ventral acute spine.

Maxilla II rounded lobe bearing two robust plumose apical setae, approximately equal.

Phyllopodia with gross structure typical for genus. Thoracopod I ( Fig. 4A ), with the first three endites (I to III) arcuate, rounded. Endite I and II fused, four to five times as broad as long. Endite III two times as broad as long, with two plumose acute spines 0.5 x broad of the endite. Endites I to III margined with long plumose setae, four to five times the endite length, decreasing in length medially. Endites IV to VI rounded as broad as long ( Fig. 4C ). Endite IV with six plumose acute spines, each two times the endite length. Endite V and VI with four plumose acute spines, each two times the endite length.

Thoracopod VI ( Fig. 4E ), with endite I and II fused, arcuate, rounded, five times as broad as long. Endite III, arcuate, rounded, two times as broad as long. Endites I to III margined with long plumose setae, five to six times the endite length, decreasing in length medially. Endite IV and V lamellar, with two plumose acute spines each twice the endite length. Endite VI lamellar, with three plumose acute spines, each two times the endite length.

Thoracopods I to X with endopod ( Fig. 4B ) broad, forming right angle to limb, bearing short, plumose acute marginal spines. Exopod oval, margined with a few small plumose spines and a long plumose setae apically. Epipodite subcylindrical, length 4x width. Praepipodite completely divided in two, broadly rounded distally, with margin serrate and inerm.

Thoracopod XI ( Fig. 4D ), with endite I and II fused, arcuate, rounded, six times as broad as long. Endite III, arcuate, rounded, two times as broad as long. Endites I to III margined with plumose setae, two to three times the endite length, decreasing in length medially. Endites IV to VI rounded as broad as long. Endite IV and V with 3 plumose acute spines each two times the endite length. Endite VI with four plumose acute spines, each two times the endite length.

Thoracopod XI without praepipodite (branchial lamina) and with a conical epipodite three times longer than its width, with acute apex and without spine or setae.

Gonopod ( Fig. 5B ) typical for the genus, with a lateral conical lobe. Gonopod rigid basal portion subtriangular, medially margined in dense setae. Eversible portion of the gonopods ( Fig. 5A ) represented by conical and curved apex bearing one tiny tubercle.

Abdominal-somites smooth, without projections.

Cercopods length does not exceed the length of last three abdominal segments; cercopods bordered with long plumose setae.

Female. transparent to greenish colour with vermillion furcae.

Second antennae slightly shorter by 20 % than the first pair of antennae, flattened, subconical apex acute.

Thoracopods I-XI ( Fig. 4G, H, I ) as in the male.

Genital somites. First genital somite reaches half the length of the second one ( Fig. 5C ).

Brood pouch conical, extending to the third or fourth abdominal somite with gonopore typical for genus.

Abdominal somites and cercopods ( Fig. 5D ) similar to those of males.

Eggs. ( Fig. 6 ) shell with high and thin palisaded structure delimiting more or less regular polygons. Diameter of eggs: (448.24 ± 30.93 µm, n =90).

Size. Male average length 17.4 ± 1.66 mm (14-21.3 mm, N = 19). Female average length of 17.9 ± 2 mm (14- 19.7 mm, N = 6),

Differential diagnosis. Chirocephalus sanhadjaensis . sp. nov. is most similar to C. marchesonii and C. tauricus . These species are separated from all other Chirocephalus by the shape of the male antennal appendage and by large eggs. Chirocephalus sanhadjaensis . sp. nov. is separated from C. marchesonni and C. tauricus by the second antenna distal antennomere having a distinct basomedial projection and proximal spiniform projections present only in this species.

In C. sanhadjaensis . sp. nov., the male second antennal distal antennomere is slightly curved in its proximal portion, and almost straight for the apical length as in C. marchesonii Ruffo & Vesentini, 1957 , C. neumanni Hartland-Rowe, 1967 and C. algidus Cottarelli et al. 2010 but not in C. diaphanus Prévost, 1803 or C. salinus Daday, 1910 , where the distal portion is more curved, or in C. tauricus Pesta, 1921 where the distal antennomere widens apically and is somewhat spatulate.

In C. sanhadjaensis sp. nov. the basal process of the distal antennomere of the antennae is well developed, rather straight with denticles and a slightly curved apex, while this basal process of the distal antennomere is short and slightly pointed, devoid of teeth in C. marchesonii . Chirocephalus algidus has a quite elongated and narrow, straight and dentate basal process, and in C. tauricus the basal process is small and pointed, with a curved apex directed backwards ( Cottarelli et al. 2010).

The long basolateral digitiform expansions of the dorsal lamella are present in many species of the genus Chirocephalus , e.g. C. diaphanus , C. salinus , also in representatives of other species-groups of the genus Chirocephalus , e.g. C. sarpedonis Cottarelli et al. 2017 , C. croaticus Steuer, 1899 , C. kerkyrensis Pesta, 1936 ; but they are absent in C. sanhadjaensis sp. nov. as in C. appendicularis Vàvra, 1905 , C. marchesonii , C. tauricus , C. skorikowi Daday, 1913 , C. weisigi Smirnov, 1933 , C. neumanni , C. ponticus Beladjal & Mertens, 1997 and C. algidus Cottarelli et al. 2010 . The dorsal lamella of C. sanhadjaensis sp. nov. and C. marchesonii is 1.5x long than the basal lamella. In C. tauricus and C. weisigi the dorsal lamella is short, half the length of the basal lamella, while in C. algidus the dorsal lamella, is somewhat longer than the basal lamella ( Cottarelli et al. 2010). Basal lamella of C. sanhadjaensis sp. nov exhibits a small carina, present also in C. marchesonii , C. algidus and several other taxa of the “ diaphanus ” group, where the size of carina differs between species. However, it is absent in C. tauricus and C. salinus . The outline of the basal lamella of C. sanhadjaensis resembles that of C. tauricus and C. marchesonii , with margins bearing small, evenly distributed papillae, with the medial margin bearing several papillae.

The brood pouch of C. sanhadjaensis sp. nov. is conical, reaching the 3 th or 4 th abdominal segment and is similar in shape to that of C. diaphanus , C. salinus and several other species of the “ diaphanus ” group. The brood pouch of C. algidus is thick and very short (does not reach the length of the two subsequent somites), while in C. tauricus and C. marchesonii the brood pouch is somewhat longer than C. algidus although different in shape, swollen in C. tauricus ( Cottarelli et al. 2010) .

In C. sanhadjaensis sp. nov. the egg ornamentations are similar to those of C. diaphanus and many other species in the genus. However, the egg diameter is particularly large (448.24 µm). Indeed, C. marchesonii is the second species in the group that produces eggs with a diameters exceeding 430 µm, but its eggs are easily distinguishable by their smooth and fibrous surface ( Mura et al. 1978; Mura, 2001).

Figures

FIGURE 1. Map showing the distribution of Chirocephalus sanhadjensis sp.nov. in Algeria. (Stars: Localities of C. sanhadjensis sp. nov., Dotted line: Borders of Province, Black: Urban regions, Grey: Lake Fetzara).

FIGURE 2. Illustration of Chirocephalus sanhadjaensis sp.nov. biotops, A, Ain-Magroun pool. B, Belkroun pool.

FIGURE 3. Chirocephalus sanhadjaensis sp. nov. A-D, male from Ain-Magroun. E, male from Belkroun. A, head, left side, anterior view. B, antennal appendage. C, second antenna. D, enlarged detail of the apophysis of the distal antennomere. E, head, right side, anterior view.

FIGURE 4. Chirocephalus sanhadjaensis sp. nov. from Ain-Magroun. A–F, male. G-I, female. A, first pair of thoracic limb. B, enlarged detail of the endopod P1. C, enlarged detail of the endites P1. D, eleventh pair of thoracic limb. E, sixth pair of thoracic limb. F, enlarged detail of the endites of the sixth pair of thoracic limb. G, first pair of thoracic limb. H, eleventh pair of thoracic limb. I, sixth pair of thoracic limb.

FIGURE 5. Chirocephalus sanhadjaensis sp. nov. from Ain-Magroun. A-B, male. C-D, female. A, eversible tip of hemipenis. B, genital segments of male. C, abdominal segments and ovisac of female. D, cercopods.

FIGURE 6. SEM micrographs of eggs. A-C-E, eggs of C. sanhadjaensis sp. nov. from Ain-Magroun. B-D-F, eggs of C. sanhadjaensis sp. nov. from Belkroun. Scale bars: A, B: 200 µm; C, D, E, and F: 100 µm.