Myrmozercon sternalis, Babaeian & Joharchi & Saboori, 2013

Babaeian, E., Joharchi, O. & Saboori, A., 2013, A New Species Of Myrmozercon Berlese (Acari: Mesostigmata: Laelapidae) Associated With Ant From Iran, Acarologia 53 (4), pp. 453-460 : 454-458

Myrmozercon sternalis n. sp.

( Figures 1 – 3 )

Specimens examined — Holotype, female, Iran, Karaj, Najm Abad, 35°52’ N, 50°30’ E, alt. 1124 m a.s.l., 9 March 2013, E. Babaeian coll., in the nest of Formica sp.. Paratypes, seven females, same data as holotype .

Diagnosis — Mellitiphine laelapid mites. Dorsal shield oval shaped, truncated posteriorly and does not completely cover idiosoma, with 38 pairs of setae and one unpaired setae, all setae (excluding j1) long and barbed; sternal shield deeply concave anteriorly, horse-shoe like and free of narrow endopodal shields; genital shield narrow posteriorly; peritremes long, fixed and movable digits without teeth; epistome with serrate anterior margin and femur IV with five setae.

Description — Female

Dorsal idiosoma ( Figure 1A ) — Length 626 – 653, dorsal shield length 596 – 619, width 450 – 505 (n = 6), oval, truncate at posterior region and not covering entire idiosoma, with reticular pattern on the whole surface, with complement of 38 pairs of setae, and one unpaired postero-median (Jx): 21 pairs (j1-j6, z1-z6, s1-s5, r2-r5) in podonotum and 17 pairs (J1- J5, Z1- Z5, S1- S5, Zx2-Zx3) in opistonotum and one additional unpaired setae between J2- J3; three pairs of R setae in soft skin posterior to shield, all setae long, thickened and barbed apically ( Figure 1B ), posterior setae longer than anterior ones and extending well behind the base of next posterior seta. Shield with 21 pairs of pore-like structures, apparently including six pairs of gland pores and 15 pairs of poroids; posterior soft integument with a pair of lyrifissures, lyrifissures near the base of j1 large and slit-like, others smaller and ovoid.

Ventral idiosoma ( Figure 2A ) — Tritosternal base narrow 27 – 37 long, and with pilose paired lacinia 67 – 79 ( Figure 2C ); presternal platelets absent, sternal shield 25 long along midline, with a few lines, distance between the most anterior point to the most posterior point 176 – 183, 200 – 208 width at widest point, and fused with endopodal extension between coxae I-II and II-III; with strongly concave anterior margin, bearing setae st1-st3 smooth, thin and 50 – 54, 47 – 56, 45 – 50 long respectively, with two pairs of lyrifissures, oriented obliquely; st4 50 – 52 and third pair of lyrifissure on soft cuticle. Endopodal plates beside coxae III and IV, narrow and separate from sternal shield. Narrow exopodal plates enclosing coxa IV posteriorly, gv 2 in soft cuticle and small parapodal plate between coxa II-III (not illustrated). Genital shield with conspicuous reticulation, 262 – 277 long and 131-141 wide (along midline and at level of st5 respectively, with hyaline and lineate anterior margin, tapered toward the apex and pointed posteriorly, with eight longitudinal cells in the central area bordered by two lines forming an inverted-V, bearing st5 45 – 57 on lateral edges, greatest width a little behind st5, lyrifissure iv5 located on soft cuticle anteromedial to exopodal shield. Metapodal shields narrow, 34 – 40 long and 6 – 8 wide, two small paragenital plateles beside seta Zv1. Opisthogaster with five pairs of lyrifissures and 11 pairs of heterogeneous setae, each seta arising on small and rounded platelet, Zv1 and Jv2 are smooth setae, remaining setae barbed distally. Anal shield sub-triangualr and straight anteriorly, 134 – 144 long and 84 – 92 wide, ornate with faint striations in pre-anal region, post-anal seta 74 – 79 thickened, about two times longer than paraanal setae 34 – 45, adanal gland pores gv3 on lateral edges of the shield, near posterior margin of anus, cribrum narrow and inserted on posterior margin, anus large and anterior to flanking para-anal setae. Peritremes long, narrow, 309 – 349 long, extending from stigmata at mid-level of coxae III-IV, extending to level of z1, peritrematal plates smooth, free posteriorly and fused to dorsal shield near s1, bearing three pairs of gland pores gp and three pairs of lyrifissures iv, post-stigmatal section elongate, 55 – 73 long, bearing gland pore gp3 and two ip ( Figure 2B ).

Gnathosoma ( Figures 1 C-E, 2D) — Epistome triangular, with denticulate anterior margin ( Figure 1E ). Subcapitulum ( Figure 1D ): hypostomal (hp1, hp2, hp3) and capitular setae simple, smooth, 15 – 18, 13 – 17, 42 – 47 and 27 – 32 long, respectively; deutosternal groove with seven rows of denticles, rows progressively widened from the base to the end, preceded anteriorly by a smooth ridge; internal malae slender, abutting and pointed apically, finely fringed, extending beyond anterior margin of corniculi; external malae with nine or eleven points; labrum slender, with pilose surface. Corniculi short, membranose and bilobed at tip, 22 – 27 long. Salivary stili thin, distinct and slightly thicker basally. Chelicerae ( Figure 2D ) with middle segment 99 – 114 long ending in fixed digit 30 – 32, with movable digit edentate, 37 long from base to tip, with fringed arthrodial corona; fixed digit edentate, with only a large, blunt tooth near its base, 32 long, total lenght 166 – 173; pilus dentilis absent; dorsal seta smooth, posteriad dorsal lyrifissure; antiaxial lyrifissure long. Palpi ( Figure 1E ) 140 – 156 long, with normal setation (2-5-6-14-15); palptarsal apotele two-tined, ventral tine slightly shorter than dorsal tine ( Figure 1E ); palp trochanter with lateral seta longer, 1.6 times longer than the other seta on the segment; palp genu seta al1 thickened, al2 thickened and apically trifurcate ( Figure 1E ).

Legs — Legs I-IV ( Figures 3 A-D) with well developed claws and pulvilli; all setae smooth. Leg I very elongate, 705 – 668 long, legs II-IV 438 – 465, 448 – 455 and 606 – 629 long, respectively. Setation of legs: Leg I: coxa 0 0/1 0/1 0, trochanter 1 0/2 1/1 1 (pd thickened), femur 2 3/1 2/1 2 (ad3 thin, ad1 thickened), genu 2 3/2 3/1 2, tibia 2 3/2 3/1 2 (Fig- ure 3A). Leg II: coxa 0 0/1 0/1 0, trochanter 1 1/0 0/2 1, femur 2 3/1 2/1 1 (ad1 thickened, pd2 slightly thickened), genu 2 3/1 2/1 2 (av and pv slightly thickened), tibia 2 2/1 2/1 2 (av and pv slightly thickened) (Figure 3B). Leg III: coxa 0 0/1 0/1 0, trochanter 1 1/1 0/1 1 (al and ad thickened), femur 1 2/1 1/0 1 (al slightly thickened, ad1 thickened), genu 2 2/1 2/1 1 (av and pv slightly thickened), tibia 2 1/1 2/1 1 (av and pv slightly thickened) (Figure 3C). Leg IV: coxa 0 0/1 0/0 0, trochenter 1 1/1 1/0 1 (al slightly thickened, ad thickened), femur 1 1/0 1/0 1 (al, ad and av slightly thickened), genu 2 2/1 3/0 1 (av thickened), tibia 2 1/1 3/1 1 (av and pv slightly thickened) (Figure 3D). Tarsi II-IV with 18 setae (3 3/2 3/2 3) + mv, md.

Etymology — The name of the new species "sternalis" is derived from the distinctive shape of the sternal shield.

Notes — According to the key to species of Myrmozercon occurring in the Palaearctic Region presented by Joharchi and Moradi (2013), Myrmozercon sternalis n. sp. runs to Myrmozercon michaeli Joharchi, 2013 (dorsal shield hypotrichous and truncated, peritreme long, femur I with less than four ventral setae (including two ventral setae), metasternal setae st4 present and almost all dorsal setae barbed in apical end). However, M. sternalis n. sp. differs from M. michaeli and other similar congeners by following combination of characters: (1) sternal shield deeply concave anteromedially and horse-shoe like; (2) dorsal shield setae thickened and elongated; (3) movable and fixed digits completely edentate; (4) femur I with two ventral setae; (5) peritreme very long; (6) femur and genu IV each with five and nine setae, respectively.

Figures

FIGURE 1: Myrmozercon sternalis n. sp.: A – dorsal shield; B – detail of a dorsal seta, not to scale; C – epistome; D – subcapitulum; E – palp.

FIGURE 2: Myrmozercon sternalis n. sp.: A – ventral shield; B – detail of peritrematal plate; C – tritosternum; D – chelicera.

FIGURE 3: Myrmozercon sternalis n. sp.: A – leg I, dorsal aspect; B – leg II, dorsal aspect; C – leg III, dorsal aspect; D – leg IV, dorsal aspect.