Amerozercon annularis, Ujvári, 2013

Ujvári, Zsolt, 2013, Amerozercon Halašková, 1969 species (Acari: Mesostigmata: Zerconidae) of the United States of America, Journal of Natural History (J. Nat. Hist.) 47 (15 - 16), pp. 1093-1120 : 1102-1105

Amerozercon annularis sp. nov.

( Figures 2G, H and 5A, B )

Material examined ( Figure 3 )

Holotype: female, USA, Virginia, Nelson County, Washington National Forest, Blue Ridge Parkway , Wintergreen Trail , ex. litter and moss by small stream, 1 October 1992, leg. V. Behan . Paratype: one female, locality and date as for the holotype. Both specimens are deposited in CNC (coll. number of holotype: CNCAZ0482 ; coll. number of paratype: CNCAZ0484 ) .

Diagnosis

Anterior margin of ventrianal shield with two pairs of setae (setae Zv1 present). Central podonotal setae, s1, r1, J1, Z1 and S2 short and smooth, other dorsal setae distinctly pilose. Third pair of opisthonotal pores (Po3) absent. Dorsal cavities of different size, the lateral pair large, well-sclerotized, ring-shaped, the central pair weakly developed. Anterior and lateral surface of podonotum covered by tile-like pattern, posterocentral surface of podonotum and anterior surface of opisthonotum bearing net-like ornamentation with refracting dots at the connecting points, posterior surface of opisthonotum with alveolar pits.

Description – female

Length of idiosoma: 333–344 µm (339 µm); width: 274 µm (n = 2).

Dorsal side ( Figure 5A ). Podonotum with 20 pairs of setae, j1–6, z2–6, s1–6, r2 and r4–5 inserted dorsally, r1 and r3 inserted ventrally, on peritrematal shields (see at ventral side). Marginal setae of podonotum (z3, s2, r2, s3, r4, r5, s6) and j1–2 feathered and generally slightly longer than other podonotal setae, which are smooth and needlelike. Glands gds1 (po1) situated anteromedially to s1; gdj4 (po2) situated medially to z4; gds4 (po3) on line connecting s4 and s5, in equidistant position. Anterior and lateral surface of podonotum covered by tile-like pattern, posterocentral surface bearing net-like ornamentation with refracting dots at the connecting points.

Opisthonotum with 21–22 pairs of setae, J1–5, Z1–5, S1–5, marginal R-series with six to seven pairs of setae (usually seven pairs). None of opisthonotal setae reaching bases of the following ones in the series. Each J-seta short, J1 smooth and needlelike, J2–5 pointed and pilose. Setae J1–5 constitute parallel rows, setae J5 inserted

bases in Amerozercon annularis sp. nov. anteriorly to central dorsal cavities and not reaching their margins. Setae Z1 and S2 short, smooth and needle-like. Setae S2 situated on line connecting Z1 and S1, somewhat nearer to Z1. Setae Z2–4 and S3–4 short, pointed, pilose, none of them expanding beyond the margin of opisthonotum. Setae Z5 and S5 feathered, longer than the rest of opisthonotal setae. Each marginal seta feathered, approximately as long as central opisthonotal setae. Length of opisthonotal setae and distances between their insertions as in Table 3. Glands gdz6 (Po1) situated anteromedially to insertions of S2; gdZ2 (Po2) on line connecting Z1 and Z2, near Z2; third pair of opisthonotal pores (Po3) absent; gdS5 (Po4) anteromedially to S5. Marginal serration shallow and obtuse. Anterior surface of opisthonotum (to level of setae J2-Z2-S3) bearing net-like ornamentation with refracting dots at the connecting points, posterior surface with small to medium sized alveolar pits. Lateral dorsal cavities large, well-sclerotized and ring-shaped. The central pair small, weakly developed, without marginal sclerotization.

Ventral side ( Figure 5B ). Shape of peritrematal shields and peritrematal setae typical for the genus. Peritremes bent, with a distinct dilatation near the stigma. Peritrematal shields covered by some longitudinal lines. Sternal shield well sclerotized, 62 µm long and 45 µm wide at the level of setae st2, with concave posterior margin and reticulate ornamentation. Adgenital glands gv2 with one or two openings. Ventrianal chaetotaxy complete, setae Zv1 present. Postanal seta, preanal and adanal setae short, smooth and needle-like. Setae Jv5 similar in appearance to marginal setae of opisthonotum, feathered. Anal valves with vestigial euanal setae. Glands gv3 situated anterolaterally to adanal setae. Anterior surface of ventrianal shield covered by squamous pattern to level of adanal setae and Jv4.

Gnathosoma

Situation of hypostomal and subcapitular setae typical for the family. Setae h1 elongate, needle-like. Setae h2–3 shorter than h1, needle-like, h4 longer than previous setae, serrate. Corniculi horn-like, internal malae with a pair of bifurcate anterocentral branches and with serrate margins. Chelicerae relatively slender, fixed digit with

six teeth, movable digit with four or five teeth. Epistome ( Figure 2G, H ) typical for the genus Amerozercon , of Zercon - type (see Ujvári 2011b).

Male and immature stages

Unknown.

Etymology

The name of the new species refers to the ring-shaped lateral dorsal cavities (the Latin epithet “ annularis ” means annular, ringed).

Remarks

The new species corresponds in many important diagnostic characteristics (e.g. shape of peritrematal setae, number of R-setae, presence of gland openings gv2, situation of gv3 etc.) with the genus Amerozercon . Altough male specimens have not been found (which carry one of the most important character of the genus), the absence of the third pair of opisthonotal pores (Po3) and the different size and shape of dorsal cavities also suggest that the species is related to A. suspiciosus Halašková, 1969 and other species described below, therefore A. annularis sp. nov. is placed in the genus Amerozercon .

The weakly developed central dorsal cavities without marginal sclerotization and the large, ring-shaped lateral dorsal cavities are unique features within the genus.

Figures

Figure 2. Different structures of Amerozercon species. (A–C) Epistomes of Amerozercon minimus females; (D, E) epistomes of Amerozercon suspiciosus females; (F) chelicera of A. suspiciosus male; (G, H) epistomes of Amerozercon annularis sp. nov. females; (I) epistome of Amerozercon auricularis sp. nov. female; (J) epistome of Amerozercon halaskovae sp. nov. female;

Figure 3. Occurrences of Amerozercon species.

Figure 5. Amerozercon annularis sp. nov. female. (A) Dorsal view; (B) ventral view.