Typhlocirolana ichkeuli, Valle, Della, 2009

Valle, Della, 2009, First record of the genus Typhlocirolana Racovitza, 1905 (Isopoda: Cirolanidae) from Tunisia and description of a new species from the National park of Ichkeul, Zootaxa 2176, pp. 57-64 : 58-63

publication ID	https://doi.org/ 10.5281/zenodo.189370
DOI	https://doi.org/10.5281/zenodo.6223499
persistent identifier	https://treatment.plazi.org/id/03C1879C-E33A-FFAF-FF15-FCD3FC9CFD4A
treatment provided by	Plazi
scientific name	Typhlocirolana ichkeuli
status	sp. nov.

Treatment

Typhlocirolana ichkeuli View in CoL sp. nov.

( Figs 1 View FIGURE 1 –4)

Material examined. Holotype. 3 ( MZUF 3582),Dejebel Ichkeul, 37°07’06.0”N, 09°40’23.6”E, well N°1, 29 October 2003.

Paratypes. Ƥ ( MZUF 3583), 2 3 ( MZUF 3584) and 2 Ƥ ( MZUF 3585), same data as holotype.

Other non-catalogued material. 7 3 and 14 Ƥ, 30 October 2003, Dejebel Ichkeul, well N°1, Messana, Della Valle and Ghlala coll.; 130 3 and 99 Ƥ, 25 March 2004, 110 specimens with one ovigerous female, 20 October 2004, Dejebel Ichkeul, well N°2, A. Ghlala coll.

Description. Body depigmented, dorsoventrally flattened, pereonite margins almost parallel ( Fig. 1 View FIGURE 1 A). Body 4.5 times longer than broad. Pleotelson triangular with rounded margins and 10 short and simple setae on posterior margin.

Antennula reaching the first pereonite. Peduncle articles increasing in length towards distal end ( Fig. 1 View FIGURE 1 E). Flagellum with 6–8 articles. Aesthetascs present from second to penultimate article. Aesthetascs formula is: 121221. Three peduncular and last flagellar articles bearing 3 to 8 setae including short simple type II setae and some long plumose type I setae.

Antenna flagellar tip reaching pereonite 4, total length/peduncle length ratio 3.5. Flagellum with about 28 articles, with many setae, mainly long and simple type II setae, some long plumose type I setae and one plumose seta of type I with supracuticular pocket on the first peduncular article ( Fig. 1 View FIGURE 1 B–D).

Right mandible pars incisiva with 3 teeth, one longest ( Fig. 2 View FIGURE 2 B); 4 teeth in left mandible ( Fig. 2 View FIGURE 2 A); spine row bearing 11 to 13 spines of different length; pars molaris bearing 20 to 25 stout spines. Palp article 2 with 13 setae, 2 or 3 distal simple type II setae, 2 basal thin plumose type I setae and 9 strong type I setae, article 3 with 11 plumose setae, distal-most seta longest.

Maxilla 1 medial lobe with 4 stout circomplumose type I setae and 2 small simple and thin type II other setae ( Fig. 2 View FIGURE 2 C). Lateral lobe with 11 robust type II setae, one long and simple type I seta and one plumose seta on disto-medial corner.

Maxilla 2 medial lobe with 12 long plumose setae of type II and two simple ones ( Fig. 2 View FIGURE 2 F). Middle lobe with 5 and lateral lobe with 4 long denticulate on distal margin type II setae.

Maxilliped palp with 5 articles ( Fig. 2 View FIGURE 2 D). Article 1 with single mediodistal simple type I seta; article 2 with seven simple setae on medial margin and one on lateral distal corner; article 3 with 14 simple setae on internal margin and 6 on the external one; article 4 with 9 setae on internal margin and 2 on external margin; article 5 with 12 distal setae, 9 plumose type I setae on medial and distal margin, and 3 simple type II setae on lateral margin. Endite with single hook and 7 long plumose type I setae ( Fig. 2 View FIGURE 2 E).

Pereopod 1 shorter and stouter than other pereopods. Basis 2 time as long as wide, with 1 plumose type I seta and a short simple type II seta on the dorsal margin and 2 small similar setae on distal inferior angle ( Fig. 3 View FIGURE 3 A). Ischium 0.7 as long as basis, 1.6 times as long as wide, with 2 short and simple setae on inferior margin and 2 on superior margin. Merus about 0.6 times as long as ischium, 2 simple setae, 2 spiniform setae with additional setule and 3 molariform robust conate setae on inferior margin. Distal superior corner with 2 short type II setae, serrate with distal margin dentate. Carpus with 2 simple setae and single stout spiniform seta with additional setule on distal inferior corner. Propodus 0.8 time as long as ischium, about 1.7 times as long as wide with 3 setae on inferior margin, 2 of which with additional seta and 1 simple short seta on superior corner. Dactylus about 0.3 times as long as propodus, with accessory unguis and 4 short simple setae on distal inferior corner and 2 short distal setae on lateral surface.

Pereopod 2 basis with 4 type I palmate setae. Merus with 4 stout robust setae with additional seta. Propodus, 6 times as long as wide with 8 setae on inferior margin, 2 terminal and 1 median are simple type II setae and 5 are strong spiniform and cuspidate type II setae with additional setula. Dactylus with trifid seta ( Fig. 3 View FIGURE 3 C).

Pereopod 2–7 similar to each other and progressively growing in length from 2 to 7. Pereopods 2 and 3 without propodal organ in both males and females ( Fig. 3 View FIGURE 3 B, D).

Pleopod 1 with 6 coupling hooks on mesial margin of sympod; endopod narrower than exopod, about half of width. Endopod with 14–16 plumose setae, exopod with 24–26 plumose marginal setae of type I ( Fig. 3 View FIGURE 3 F).

Pleopod 2 sympod with 8 coupling hooks, and one short and simple single seta on lateral distal corner and on medial margin, exopod oval, larger in females than in males, with 26–32 plumose marginal setae of type I. Endopod with 6–12 plumose setae. Appendix masculina scimitar shaped externally directed, exceeding exopod by 0.3 of length ( Fig. 3 View FIGURE 3 G).

Pleopod 3 sympod with 4 coupling hooks and one plumose seta on internal margin, single short and simple seta on distal external corner. Exopod oval, with 31 marginal plumose setae, a few scalespines and two short simple setae on lateral margin. Medially transverse suture present ( Fig. 3 View FIGURE 3 H).

Pleopod 4 sympod with 5 coupling hooks on inner margin, and one seta on distal external corner. Exopodite with reduced chaetotaxis, with 9 distal plumose setae on internal margin and 7 setae, three of which plumose, on external margin ( Fig. 3 View FIGURE 3 I).

Pleopod 5 similar to third and fourth, with clear transverse suture; the sympod, without coupling hook, has a seta on distal external corne; chaetotaxis of exopod reduced with only 4 plumose setae of type I on internal margin of distal part ( Fig. 3 View FIGURE 3 K).

Uropods sympod with 6 plumose setae on internal margin and 3 spiniform simple setae (Type IIc, Watling 1989) with additional setula on mesial margin ( Fig. 1 View FIGURE 1 H). Exopod narrow, as long as endopod, tapering distally, maximal width about half that of endopod; lateral margin with one spiniform seta with additional setula; mesial margin with 6 plumose setae. Apex with 9 long simple setae. Endopod with 8 palmate plumose setae on mesial margin, lateral margin with 8 plumose setae and one spiniform seta with additional setula. Apex bearing 9 setae, 2 longer than the 7 others.

Pleotelson triangular with a rounded apex bearing 8 short simple setae on distal margin ( Fig. 1 View FIGURE 1 F–G).

Remarks. Typhlocirolana ichkeuli sp. nov. is most similar to the Algerian species Typhlocirolana fontis Gurney, 1908 . However, several characteristics distinguish the two species. Typhlocirolana . ichkeuli sp. nov. has no propodial organ, and the setation of first maxilla and the shape of maxilliped are different. The first pereopod is very similar in shape and setation, but some differences are in the setation of the other pereopods of the two species.

The “ Typhlocirolana group” consists of two subgroups, i.e. the western Mediterranean group (genus Typhlocirolana ), which occurs in Spain, Morocco, Italy and Algeria ( Boutin et al. 2002). This group following these authors could have colonized the subterranean habitat during the late cretaceous marine regression. The second subgroup consists of two genera, the eastern Turcolana and the western Marocolana , occurring in Turkey and Morocco, respectively, colonizing underground water during the Miocene and the Eocene. The marine ancestor of the genus Typhlocirolana probably colonized the underground waters in the Mesozoic during the late Cretaceous regressions ( Boutin 1993).

The sampling site is located on a geological fault in NW-SE direction. Typhlocirolana ichkeuli nov. sp. was found only in one single site (in fact in three wells being very close, within a radius of some 20 metres) despite extensive research in a great number of stations in the area. This indicates a highly restricted distribution of the species.

Stygobitic Mediterranean Cirolanidae form a homogeneous group ( Botosaneanu 1986; Wägele 1989). Indeed, the Mediterranean species show strong morphological similarities. Generally, the form and the chaetotaxy of pereopod 1 are quite similar in the Cirolanidae ( Racovitza, 1912) . However, Typhlocirolana ichkeuli sp. nov., differs from Moroccan and Algerian species in having the dactylus whith four setae. The chaetotaxy of the merus of pereopod 1 is similar in all the species of Typhlocirolana of North Africa except for Typhlocirolana buxtoni which has 4 “molariform spines” ( Nourisson 1956). In T. ichkeuli sp. nov. the distal part of the merus of pereopod 1 is denticulated; this characteristic had never been observed before. Merus of pereopod 2 with 4 robust spine with additional seta (7 in T. haouzensis ).

The addition of T. ichkeuli sp. nov., constitutes a considerable range-extension for the genus and is the first record of a species of Typhlocirolana from Tunisia.