Petrobia (Petrobia) pseudotetranychina, Auger, Philippe, Chaaban, Samah Ben, Grissa, Kaouthar Lebdi, Khoualdia, Othman & Flechtmann, Carlos H. W., 2009

Auger, Philippe, Chaaban, Samah Ben, Grissa, Kaouthar Lebdi, Khoualdia, Othman & Flechtmann, Carlos H. W., 2009, Five new species of Tetranychidae (Acarina, Prostigmata) from south Tunisian oasis areas, Zootaxa 2232, pp. 29-49 : 40-44

publication ID 10.5281/zenodo.190324

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Petrobia (Petrobia) pseudotetranychina

sp. nov.

Petrobia (Petrobia) pseudotetranychina sp. nov. Auger & Flechtmann

(Figures 40–56)

The sub-genus assignation of the species described below was quite problematic. One of its morphological characteristics is the presence of obvious bulges on sacral (f) and clunal (h) setae insertions. According to diagnostic features, Wainstein (1960) has proposed to divide the genus Petrobia into three sub-genera. The sub-genus Tetranychina Banks can be separated from the two others by the presence of dorsal setae set on tubercles. In addition to the absence of tubercles on the dorsum, the two remaining sub-genera, Petrobia ( sensu stricto) and Mesotetranychus Reck , are segregated by the presence of anastomosing and simple peritremes respectively. Nevertheless the word "tubercle" may be unclear. The diagnose of Tetranychina by Meyer (1974) increases the confusion because members of Tetranychina may be recognised by "[...] hysterosomal setae located on prominent tubercles or else only some dorsal setae on the opisthosoma may be set on tubercles". Does tubercle refer to a simple obvious bulge of the integument or to a large protuberance? Depending on the species the answer is sometimes evident but sometimes difficult. One species, P. (P) phaceliae Tuttle and Baker, 1964, illustrates this dilemma. In their original description of this species the authors mentioned "dorsal body setae [...] not set on tubercles". In their drawing of the mite in habitus we can see that all dorsal body setae are inserted on small but obvious bulges blister-like. Later, in their "Guide to the spider mites of the United States ", the same authors mentioned in the description of this species that the dorsal body setae were inserted on small tubercles. Moreover they provided a key in which they separate P. (P.) latens from P. (P.) phaceliae by a combination of characters including the presence of some setae set on tubercles in the latter species ( Baker & Tuttle 1994). Nevertheless they kept this species assigned to the subgenus Petrobia s. str. Observations of P. (P.) latens dorsum under microscope reveal that in the caudal area slightly swollen setae insertions can be observed. As in the species we collected in Tunisia the tubercles are smaller than those present in the dorsum of P. (P.) phaceliae , we decided to assign this new species to the subgenus Petrobia s. str.

FIGURES 40, 41. Petrobia (P.) pseudotetranychina sp. nov., female. 40, dorsal aspect; 41, f 2 seta.

Type-specimens. Holotype (male), 4 male, 6 female paratypes on 11 microscopic preparations from Atriplex sp., ( Chenopodiaceae ), El Hamma, Gouvernorat de Tozeur, Tunisia, 05/06/ 2005, coll. P. Auger. Holotype, 5 female and 3 male paratypes deposited in the collection of the CBGP. 1 male and 2 female paratypes deposited in the type collection of the MNHN.

Diagnosis. The female of Petrobia (P.) pseudotetranychina resembles Petrobia (P.) latens but it can be easily distinguished by the combination of the presence of conspicuous bulges on sacral (f) and clunal (h) setae insertions and by the size of these setae which are longer than the other dorsal hysterosomals. Moreover, in P. (P.) pseudotetranychina , the medio dorsal hysterosomal striation is entirely transverse. These two species also differ in their leg chaetotaxy.

Description. Male: Holotype 367 µm long (excluding gnathosoma), gnathosoma 119 µm long. Four paratypes measured, 354–379 µm long, gnathosoma 90–125 µm long.

Dorsum – Dorsal body setae narrowly lanceolate and serate, not subspatulate as in females but slender, sub-equal in length excepted for sacrals (f) and clunals (h) longer. Sacral and clunal setae inserted in very small bulges, much smaller than in females (length of holotype and variations of four paratypes): v 2 30 (27– 33); sc 1 27 (25–33); sc 2 32 (27–32); c 1 34 (30–34); c 2 28 (28–29); c 3 35 (29–34); d 1 31 (29–30); d 2 31 (30–33); e 1 32 (31–34); e 2 38 (32–35); f 1 38 (33–39); f 2 39 (32–35); h 1 35 (32–36). Prodorsal striation with large irregular pattern medially. There are no lobes on striation.

Gnathosoma – Peritreme anastomosed distally with distal enlargement smaller compared to female. Palptarsus eupathidia and solenidion sub-equal in length.

Venter – Ventral striae without lobe.

Legs – Leg I length superior to body length, 478 (403–450) µm long (length of holotype and variations of four paratypes). Variations are observed on the chaetotaxy of tarsus I and more on tibia I. Leg chaetotaxy as follows:

I 2 − 1 − 8 − 5 − 5 + (9) [(8–10)] + 8 [6–7] duplexes − 10 + (6)[5] + 6 duplexes;

II 2 − 1 − 5 − 5 − 9 − 11 + (2) + 1 duplex;

III 1 − 1 − 3 − 3 − 8 − 11 + 1 duplex;

IV 1 − 1 − 3 − 3 − 8 − 11 + 1 duplex.

Tactile members of duplex setae on tarsi III and IV about one fourth the length of solenidia. Empodia I–IV bear true claws pad-like, about half as long as empodial claws bearing two rows of ventrally directed hairs.

Aedeagus – Shaft long 105 (94–112) µm long, twice abruptly constricted consecutively towards its distal part and ending in a needle-like tip. Whole distal part 15 (15–16) µm long.

Female: 6 females measured. Idiosoma: length 390–476 µm long, gnathosoma 143–160 µm long, width 316–378 µm.

Dorsum –Dorsal body setae short, serrate and subspatulate. Sacral (f) and clunal (h) setae slightly less spatulate and longer than other setae. Sacrals and clunals inserted in obvious bulges. Setal length variations of six paratypes: v 2 30–34; sc 1 25–29; sc 2 25–29; c 1 27–31; c 2 25–29; c 3 26–30; d 1 24–28; d 2 22–30; e 1 26 –35; e 2 30 –39; f 1 38–44; f 2 38–43; h 1 40–46.

Prodorsal integument with fine longitudinal broken lines of various lengths medially. The rest of the dorsum bears continuous smooth striae without lobes, longitudinal on prodorsum laterally, mainly transverse on hysterosoma medially and longitudinal laterally.

Gnathosoma – Stylophore rounded. Peritreme ends in anastomosing chambers. Length of solenidion and eupathidium su slightly inferior to eupathidia ul' and ul''.

Venter – Area immediatly anterior to genital flap with irregular striation. Ventral striation without lobe. Spermathecal sacculus oblong slightly enlarged distally with a rugose surface. Two pairs of para-anal and three pairs of anal setae.

Legs – Leg I slightly longer than body, 408–480 µm long (variations of six paratypes). Leg chaetotaxy as follows:

I 2 − 1 −8 − 5 − 13 + (1) − 14 + 2 duplexes;

II 2 − 1 − 5 − 5 − 9 − 11 + 1 duplex;

III 1 − 1 − 3 − 3 − 8 − 11 + 1 duplex;

IV 1 − 1 − 3 − 3 − 8 − 11 + 1 duplex.

Associated setae on tarsi III and IV with tactile setae about a sixth the length of solenidia. Empodia I–IV with true claws pad-like, about the half the length of empodial claws bearing two raws of ventrally directed hairs.

Etymology. The species designation refers to the dilemma in the generic assignation of this new Petrobia due to the ambiguity in the signification given to the word tubercle by different authors.


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