Amerozercon suspiciosus Halašková, 1969

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 : 1099-1102

Amerozercon suspiciosus Halašková, 1969

( Figures 2D–F, O–U and 4A, B )

Material examined ( Figure 3 )

USA, Tennessee, Greenbrier Ranger Station, Great Smoky Mountains National Park , 8 August 1956, leg. J.L. Bohnsack (ÉAm-028, three females, one male, deposited in HNHM) , USA, Tennessee, Great Smoky Mountains National Park , 1220 m elevation, 28 July 1956, leg. J.L. Bohnsack (ÉAm-033, three females, one male, deposited in HNHM) .

Diagnosis

Anterior margin of ventrianal shield with one pair of setae (setae Zv1 absent). Marginal podonotal setae and j1–2 feathered, central setae smooth or barbed. Setae Z1–2 smooth, J1–2 and S2 barbed, the rest of opisthonotal setae distinctly pilose. Third pair of opisthonotal pores (Po3) absent. Glands gdS5 (Po4) situated anteriorly to S5. Dorsal cavities well-sclerotized, the central pair significantly larger than the lateral pair, their axes converging posteriorly. 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, posteriormost surface of opisthonotum behind the level of setae J4-Z4-S4 with alveolar pits.

Description – female

Length of idiosoma: 317–323 µm (320 µm); width: 247 µm (n = 2).

Dorsal side ( Figure 4A ). 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 densely pilose, feathered. Setae j3, z4, s4 and s5 barbed, j4–6, z2, z5–6 and s1 smooth, needle-like. Glands gds1 (po1) not visible; gdj4 (po2) situated medially to z4; gds4 (po3) laterally to line connecting s4 and s5, near s4. Anterior and lateral surface of podonotum covered by tile-like pattern, posterocentral surface of the shield bearing net-like ornamentation with refracting dots at the connecting points.

Opisthonotum with 22 pairs of setae, J1–5, Z1–5, S1–5, R1–7. None of opisthonotal setae reaching bases of the following one in the series. Each J-setae short, J1–2 barbed, J3–5 pointed and pilose. Setae J1–5 constitute parallel rows, setae J5 inserted near the anterolateral margin of central dorsal cavities. Setae Z1–2 short, smooth and needle-like. Setae Z3–5 and S3–5 feathered, longer than J-setae. S4–5 expanding beyond margin of opisthonotum. Setae S2 inserted on line connecting Z1 and S1, somewhat nearer to Z1. Length of marginal setae and the number of pili on their surface decreasing posteriorly. Length of opisthonotal setae and distances between their insertions as in Table 2. Glands gdz6 (Po1) situated anteromedially to insertions of S2; gdZ2 (Po2) on line connecting Z2 and S2, near Z2; third pair of opisthonotal pores (Po3) absent; gdS5 (Po4) anteriorly to S5. Marginal serration shallow and obtuse. Anterior surface of opisthonotum (to level of setae J4-Z4-S4) bearing net-like ornamentation with refracting dots at the connecting points, posteriormost surface with small to medium sized alveolar pits. Dorsal cavities well-sclerotized and of different size. Lateral pair small, saddle-like, with approximately parallel axes. Central cavities significantly larger, arcuate, with axes converging posteriorly.

Ventral side ( Figure 4B ). Shape of peritrematal shields and peritrematal setae typical for the genus. Peritremes slightly bent, with a distinct dilatation near the stigma ( Figure 2O ). Peritrematal shields covered by longitudinal lines. Sternal shield well sclerotized, 54 µm long and 38 µm wide at the level of setae st2, with concave

bases in Amerozercon suspiciosus . posterior margin and reticulate ornamentation. Adgenital glands gv2 with two openings. Ventrianal chaetotaxy incomplete, setae Zv1 absent. Postanal seta short and finely pilose, preanal and adanal setae short, smooth and needle-like. Setae Jv5 pilose. 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 ( Figure 2F ) relatively slender, fixed digit with six teeth, movable digit with four teeth. Epistome ( Figure 2D, E ) typical for the genus Amerozercon , of Zercon - type (see Ujvári 2011b).

Immature stages

Unknown.

Remarks

The species was described on the basis of a single male specimen. The description and illustrations of Halašková (1969) correspond to the male specimen collected in the Great Smoky Mountains National Park; however, some central setae of podonotum are less pilose on the specimens described above. In several Zerconidae species it is a known phenomenon that some setae show intraspecific variation regarding the degree of pilosity (e.g. Ujvári 2009a), therefore I suppose that the specimens collected in the Great Smoky Mountains National Park are conspecific with A. suspiciosus .

Halašková (1969) diagnosed glands gds1 (po1) as they are situated anteriorly to insertions of j3. In that position there are conspicuous rotund structures, but they are muscle scars, not gland poroids.

Halašková (1969) gave the following dimensions of the idiosoma of male: body length 519 µm, width 403 µm. This size is significantly larger than that of the male specimen from Great Smoky Mountains National Park. But length of the setae of both specimens show similar measurements, and their proportion to the body is also similar based on the illustrations of Halašková (1969). Therefore it seems that Halašková (1969) measured erroneously the dimensions of idiosoma, the correct values (calculated from the length of setae, measuring the original figures) are the following: length 218 µm, width 177 µm. Latter values are approximately similar to the dimensions of the specimen from Great Smoky Mountains National Park.

Length of setae S4 (marked as S 3 in the original description) is also measured erroneously, as 29 µm. Those are similar to setae S5, and their size is only 19 µm in the type specimen.

In a previous paper, the presence of ventrianal setae Zv 1 in A. suspiciosus was discussed ( Ujvári 2011a). Halašková (1969) diagnosed Zv1 as absent. Based on her figures, however, it is evident that the number of setae represents complete ventrianal chaetotaxy. I concluded that Zv1 is present on the type specimen, but it has shifted posteriorly as a result of an aberration. But the observation of the specimens from Great Smoky Mountains National Park indicated that the species lacks Zv1 indeed, hence the question arises: is the specimen from South Carolina of Halašková conspecific with the Tennessee specimens? There are three possible explanations for the anomaly. The first is that the type specimen really lacks Zv1 and Halašková erroneously identified an extra pair of setae (perhaps one of the leg setae). The second is that the type specimen lacks Zv1, but has an extra pair of ventrianal setae, which is a very rare phenomenon within the family and in most cases it is the result of an aberration. The third, and most likely, is that Zv1 is present, but shifted posteriorly. Although many authors use the presence or absence of Zv1 as a major distinctive feature of not even species, but genera, this should be handled with care, because this character often shows sexual dimorphism or intraspecific variation (see Ujvári 2009b; Díaz-Aguilar and Ujvári 2010). The variation of this character is rarely recognized or interpreted.

In conclusion, it is thought that the type specimen of A. suspiciosus is aberrant and conspecific with the specimens described above, which usually lack setae Zv1. This should certainly be confirmed by observing other specimens collected in the type locality.

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 4. Amerozercon suspiciosus, female. (A) Dorsal view; (B) ventral view.