Typhlocirolana longimera Mahi & Messana

Mahi, Abdelhakim, Taleb, Amina, Belaidi, Nouria & Messana, Giuseppe, 2017, Typhlocirolanalongimera sp. n. (Crustacea, Isopoda, Cirolanidae) from north-western Algerian ground waters with notes on Algerian Typhlocirolana, Subterranean Biology 22, pp. 27-41 : 28-32

Typhlocirolana longimera Mahi & Messana sp. n. Figs 2, 3, 4, 5

Material examined.

Holotype: 1♂, 9.8 mm wells in Ghazaouet, north–western Algeria, 35°04'34.53"N, 001°50'11.64"W; April 2011, A. Mahi legit, MZUF Coll. Crust. 4750. Paratypes: 3 ♂♂ and 4♀♀ (dissected and mounted on 40 slides), MZUF Coll. Crust. 4751; 38 ♂♂ and 129 ♀♀, MZUF Coll. Crust. 4752; 55♂♂ and 2 ♀♀, same locality and collector, coll. Mahi.

Male dimensions.

length between 9.8 mm and 10.9 mm.

Female dimensions.

length between 10.1 mm and 12.2 mm.

Etymology.

the specific name refers to the distinctive shape of the merus of pereopod 1. with its inner margin extending to half of propodite, and thus being longer than in any other species of Typhlocirolana .

Description.

A small–medium Typhlocirolana , epimera II–VII carinate, merus of I pereiopod long, depassing carpus and reaching 2/3 the length of propus, Penial processes about (1/4) length of pereonite 7. Pleotelson triangular, bearing 8-13 short simple setae on distal margin and 5-10 short simple sub-marginal setae (Fig. 2).

Laminia frontalis (Fig. 3g): lanceolate–clavate and strongly tridimensional, laterally flattened, tip rounded. Clypeus: flatly triangular with lateral margins rounded, labrum subrectangular, rounded margins.

Antennula (Fig. 2e): Antennula short, reaching mid-length of pereonite 1. Flagellum shorter than peduncle with 6 articles, with few simple setae, aesthetascs present from second to fourth segment. Aesthetascs formula is 022210 in male and 012220 or 012210 or 011110 in female.

Antenna (Fig. 2d): Antenna reaching the distal margin of pereonite 5, flagellum extending to posterior part of pereonite 4. Flagellum nearly 2 times longer than peduncle, with about 32 segments in male and 35 in female. Segment length regularly decreasing from the base to the apex; all segments with 5 to 9 setae, mainly long and simple setae. 1-3 long plumose setae in each of segment number 4 and 5 of peduncle, and one tufted setae in segment number 4 of peduncle.

Mandibles (Fig. 3a): incisor with three strong teeth in right mandible (Fig. 3a) and 4 in left (Fig. 3b). Lacinia mobilis bearing 13-16 toothed robust setae. Left pars molaris provided with 24 (male) to 33 (female) strong short and regular robust setae.

Palp article 1 with 1 distal simple setae; article 2 with 16-20 setae (2-3 distal long simple setae, 2-4 basal simple setae, 11-13 medial barbed setae); article 3 with 9-11 barbed setae (the 3 last one are longest); article 3 shortest.

Maxillules (Fig. 3d): internal lobe bearing 3 strong and plumose setae and 2 small simple setae. Lateral lobe with 10-11 strong and conical teeth (3 of which toothed) and 2 barbed (on one side) setae.

Maxillae (Fig. 3c): Outer lobe with 3-4 barbed setae on one side in the distal part. Inner lobe with 3-4 similar setae. Basal endite with 9 setae of different lengths, delicately plumose on the two sides and at the tip. Propod with a short simple setae in the middle of distal margin.

Maxilliped (Fig. 3e,f): Palp with 5 articles provided with setae and a well-developed endite with only one coupling hook. Article 1 with one inner simple setae at apex; article 2 with 2 on outer corner margin and 6 on inner margin; article 3 with 4 setae on outer margin and 14-18 on inner margin; article 4 with 2 setae on outer margin and 12 on inner margin (2 of which are plumose in one side); article 5 with 13-17 distal setae, all setae are simple excepted 4-5 which are plumose in one side. Endite with single hook and 4 plumose setae.

Pereiopod 1 (Fig. 4a) Basis with one tufted setae and one simple setulae on outer margin. On inner margin, 2 medial small setae and 2 small setae on distal angle. Ischium 5 setulae, 3 of which on inner margin and 2 distal near outer corner and one spine on inner distal corner. Merus with inner margin elongate, depassing carpus and reaching the 2/3 length of propodus, with 3 setulae on distal outer angle. Inner margin with 6 molariform robust conical robust setae and 2 short, robust setae with additional setule and 1 long simple setae. This armature is constant and similar in male and female. Two to three simple small setae are close to the three proximal molariform robust setae. Carpus with 2 simple setae and 1 single spine with additional setula on distal inner corner. Propodus with inner margin proximally crenulate, with 2 distal spines with additional setula (one which is stronger) and a bunch of 5 apical setae (one of which is barbed on one side). Two simple setae at distal corner on outer margin. One setula on outer side. Dactylus with 5 short setae and 1 spine with additional setula on distal inner corner, 4 subdistal setae on lateral surface.

Pereiopods 2-7 (Fig. 4 b–g) similar to each other and progressively growing in length from 2 to 7. Pereopods 2 and 3 exhibit the propodial organ in both males and females. These pereiopods differ by their chaetotaxy, bearing 2 to 5 tufted setae on outer margin of basis; 4-5 along the margin of P2-P3, 2 proximal setae on P4, 2 proximal with 1 distal setae on P5, 4 setae along margin of P6 and 3 proximal setae with penial processes on P7 and about ¼ the length of the same.

Pleopod 1 (Fig. 5a) with 5-8 coupling hooks on subdistal inner margin of sympod, single short and simple seta on outer distal angle; endopod narrower about half than exopod. Endopod with 14-16 plumose setae in male (16-20 in female), exopod with 28-29 plumose marginal setae in male (28-36 in female).

Pleopod 2 (Fig. 5b,c) sympod with 4-6 coupling hooks, and 0-2 plumose setae on lateral subdistal angle, single short and simple seta on distal external angle; exopod oval, with 31-34 plumose setae on distal margin in male and (32-39 in female). Endopod with 9-14 plumose setae. Appendix masculina scimitar shaped externally directed, exceeding exopod by 2/3 of length.

Pleopod 3 (Fig. 5d) sympod with 3-5 coupling hooks and 0-4 plumose seta on inner subdistal margin, single short and simple seta on distal outer angle. Exopod oval, with 24-31plumose setae on distal margin in male (29-37 in female), a few scales and 1-3 short simple setae on inner lateral margin. Transversal suture incomplete.

Pleopod 4 (Fig. 5e) sympod with 2-3 coupling hooks and 1-3 plumose setae on inner subdistal margin, and one simple seta on distal outer angle. Exopod with 8-9 distal inner plumose setae in male (10-11 in female), a few scales pines and 1-2 short simple setae on internal lateral margin, and 0-2 plumose setae on external lateral margin. Transversal suture complete.

Pleopod 5 (Fig. 5f) sympod has one simple setae on distal outer angle; exopod with 5-7 distal inner plumose setae. A few scale-spines and 2-3 short simple setae on inner lateral margin. Transversal suture complete.

Uropods (Fig. 2f) Sympod subtriangular. Lateral margin with 3 spines with additional setula, 1 medial and 2 on distal corner. Two small and simple setae on the outer margin. Seven to eight plumose setae distal on mesial margin in male and 8-12 in female. Exopod styliform, shorter than endopod, regularly slender from base to apex, with 2 strong robust setae with additional setula on lateral margin and 1-2 on mesial margin accompanied by 1 to 2 long simple setae and 1-2 small simple setae; outer margin with 1 small proximal spine with additional setula and one line of 3-4 small simple setae. Apex with about 13 long simple setae of different length. Endopod bottle shaped, clearly wider than exopod. Slightly longer than exopod, with 6 plumose setae on internal margin in male and 5-8 in female and 2-3 strong robust setae with additional setula. Nine tufted setae on external margin grouped by 2 or 3 proximally and distally. Apex bearing about 12 simple distal setae of different lengths.

Remarks.

Typhlocirolana longimera is different from all other Typhlocirolana species described by the combination of the following characters:

- The peculiar shape of pereiopod 1 merus, which is longer than in any other species, depassing carpus and reaching the 2/3 length of propus.

- The presence of 6 molariform conical robust setae and 2 short strong robust setae usually 4 molariform robust setae;

- Propodus of pereiopod I with only 2 distal robust setae with accessory seta on internal margin, which is proximally crenulated and devoid of setae.

- The bottle shape of uropods;

- The chaetotaxy of pleopods1-5 more abundant.

Differential diagnosis with other materiel examined.

Based on the general morphological aspect, as well as some characters, Typhlocirolana longimera sp. n. exhibits the greatest affinities with Typhlocirolana fontis and T. haouzensis Boutin, Boulanouar, Coineau & Messouli, 2002. However there is a mix of characters approaching Typhlocirolana longimera to several other Typhlocirolana species.

In addition to the main characters that make the difference with the other species of the genus Typhlocirolana , as cited above, Typhlocirolana longimera differs greatly from the others according to the aesthetasc formula of flagellum in antennulae: 122222222212 in Typhlocirolana buxtoni Racovitza, 1912, 12222212 in Typhlocirolana fontis , 12222212 in Typhlocirolana gurneyi , 121221 in T. ichkeuli Ghlala, Della Valle & Messana, 2009, 22210 in T. rifana Margalef, 1953.

Dentition and number of robust setae in propodus of pereopod I: in Typhlocirolana gurneyi not toothed with 2 or 3 short strong robust setae, in Typhlocirolana buxtoni not toothed with 3 strong robust setae, in Typhlocirolana fontis we don’t have information, in T. houzensis not toothed with 3 medio distal robust setae, in T. ichkeuli not toothed with 3 robust setae.

Propodial organ is present in both male and female in Typhlocirolana longimera as well as Typhlocirolana buxtoni , but it is present only in the male in Typhlocirolana fontis , Typhlocirolana gurneyi , T. haouzensis and Typhlocirolana tiznitensis Boulal, Boulanouar & Boutin, 2009, while, it is absent in T. ichkeuli .

The basal palp article of the mandible in Algerian species ( Typhlocirolana buxtoni , Typhlocirolana fontis and Typhlocirolana gurneyi ) including Typhlocirolana longimera , exhibits a strong plumose seta. On the contrary this article is bare in Moroccan ( T. haouzensis and Typhlocirolana tiznitensis ) and in the Tunisian species T. ichkeuli .

Article III of the mandibular palp has 30 plumose setae in the Algerian species and only 13-16 in the Moroccan one. Whereas, Typhlocirolana longimera has an intermediate position with 9-11.

Pleopod 1 exopod of Typhlocirolana longimera with 28 or 29 distal setae in male and 28 to 36 in female is different to Typhlocirolana buxtoni (40), Typhlocirolana fontis (24 in male and 20 in female), Typhlocirolana gurneyi (27), T. haouzensis (23-26 in male and 27 in female), Typhlocirolana tiznitensis (26-30) and T. ichkeuli (24-26).

A complete transversal suture is present in pleopod 3, 4 and 5 in Moroccan ( T. haouzensis and Typhlocirolana tiznitensis ) and in the Tunisian species ( T. ichkeuli ), while it is present only in pleopod 4 and 5 in Algerian species ( Typhlocirolana buxtoni , Typhlocirolana fontis and Typhlocirolana gurneyi ) including Typhlocirolana longimera .

Uropod shape of Typhlocirolana longimera is similar to Typhlocirolana buxtoni , Typhlocirolana fontis , T. haouzensis and Typhlocirolana tiznitensis .

Distal margin of the pleotelson with plumose setae in Algerian species ( Typhlocirolana buxtoni , Typhlocirolana fontis and Typhlocirolana gurneyi ), versus simple setae in Typhlocirolana longimera such as Morroccan ( T. haouzensis and Typhlocirolana tiznitensis ) and Tunisian species ( T. ichkeuli ).

During several surveys in the years 2010-2013 many specimens of the taxon Typhlocirolana where collected in the wells of Ain Temouchent, SidiYouchaa and Ghazaouet, which do not belong to the new described species. In fact the examination of several specimens led us to consider that they are related to the two species described by Racovitza (1912): Typhlocirolana fontis and Typhlocirolana gurneyi . The examination of these specimens gave the following results: