Mesostigmata Lekveishvili&Krantz

Mesostigmata Lekveishvili&Krantz - Systematic &...

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Unformatted text preview: Systematic & Applied Acarology Special Publications (2004) 20, 14 ISSN 1461-0183 A new genus of the family Sejidae (Acari: Mesostigmata) based on Sejus krantzi and S. manualkrantzi Hirschmann, 1991 MARIAM LEKVEISHVILI1 & GERALD W. KRANTZ2 1Acarology Laboratory, Museum of Biological Diversity, Ohio State University, 1315 Kinnear Rd., Columbus, OH 432121192, USA e-mail: [email protected] Department of Zoology, Oregon State University, Cordley 3029, Corvallis, OR 97331-2914, USA e-mail: [email protected] 2 Abstract Sejus manualkrantzi (Acari: Mesostigmata: Sejidae) is synonymized with S. krantzi and is assigned to a new genus, Adenosejus. Key words: Sejus, Adenosejus, krantzi, manualkrantzi In a recent revisionary work, Hirschmann (1991) synonymized the sejine genera Epicroseius (Berlese 1905), Zuluacarus (Trgrdh 1906) and Willmannia (Trgrdh 1906) under the genus Sejus Koch, 1836, described or redescribed 26 species of the newly constituted genus (Hirschmann et al. 1991), and assigned the resulting 44 recognized species to ten species groups (Hirschmann, 1991). Among the new species were S. krantzi and S. manualkrantzi, both described solely based on illustrations taken from "A Manual of Acarology" (Krantz, 1978). These illustrations, referred to in the Manual as "Sejus sp. (Oregon, USA)", were intended only to provide a typical habitus for the family Sejidae, and include drawings of the dorsum of the female (Fig. 12-1) and male (Fig. 12-2), types of dorsal setae (Fig. 12-3), the venter of the female (Fig. 12-4) and the epigynal shield (Fig. 12-5) (page 170). There was no accompanying species description. As a result of studying the drawings of the venter and dorsum of the female, Hirschmann found characters that "were not matching". For example, he noted that the shape of the venter is oval while the dorsum is pearshaped. He also noted a difference in the number of posteromarginal setae: the venter has 6 and the dorsum has 4 setae. Hirschmann also concluded that peritrematic shields are absent, and that the crateriform structures on the lateral margins of the ventrianal shield represent the bases of missing setae. Based on these observations Hirschmann described Sejus krantzi from the drawing of the female venter (Fig. 12-4 in Krantz, 1978) and S. manualkrantzi from the drawing of the female dorsum (Fig. 12-1 in Krantz, 1978). He then placed these two entities into two different species groups: S. manualkrantzi, with S. solaris in the "solaris" group and S. krantzi with S. posnaniensis and Willmannia sejiformis in the "posnaniensis" group (Hirschmann, 1991). Given Hirschmann's proclivity for using the "Gangsystematik" approach to systematics (Hirschmann, 1957), a strategy that is based on morphological characters observable in all instars, it is unclear as to why he placed these two entities in separate species groups based solely on limited female characters. 2004 Systematic & Applied Acarology Society 1 It is important to emphasize that Hirschmann's two new species were based only on illustrations, without benefit of examination of the actual specimens. We examined all slides of female specimens in the Oregon State University collection and compared these specimens with the illustrations in the Manual, and have concluded that the drawings of the venter and dorsum were made from the same specimen, a dissected female. This slide has identifying marks verifying that the illustrations were made from this specific slide (GWK). Given that the names S. krantzi and S. manualkrantzi were based on the same specimen, we herein synonymize S. manualkrantzi (syn. nov.) with S. krantzi. What about the non-matching characters of Hirschmann? The difference in shape of the dorsum vs. venter (pear-shaped vs. oval) is likely to be an artifact and, while the peritrematic shields are only partially visible in the drawings, they are in fact well developed. There are ten setae on the posterior margin of the body, six of which are positioned ventrally and four dorsally (as illustrated on Plate 12). Hirschmann assumed that the same posterior setae were represented on both dorsum and venter. The crateriform tubercles on the lateral margins of the ventrianal shield are in fact very large glands and not the bases of missing setae. Hirschmann probably did not anticipate the presence of these kinds of glands on the ventrianal shield since they do not occur in any other Sejidae that he examined. It appears, therefore, that his decision to describe two specific entities from these illustrations was based on misinterpretation of characters. Even at first glance, S. krantzi differs from other Sejidae in having three dorsal shields in the female and in lacking posterior opisthonotal projections in all postlarval instars (larvae do have such projections). The mesonotal shields in nymphs and females develop differently from those of other Sejus. They are absent in the protonymph (they are present in known protonymphs of virtually all other species of Sejus). In deutonymph, the shields ostensibly are fused with the pygidial shield to form an opisthonotal shield. This character is shared only with S. congoensis Wisniewski & Hirschmann, but the opisthonotal shield of deutonymphal S. congoensis is fused to, or contiguous with, the podonotal shield. Female S. krantzi have only one mesonotal shield instead of the four characteristic of other species of Sejus. A single mesonotal element also is found in females of the genus Epicroseius, but its shape is distinctly different from that of S. krantzi. Other characters of note include: tritosternum without lateral extensions; sternal setae st1 in female on sclerotized platelets, st2 and st4 in soft cuticle, st3 on transverse sternal element with convex anterior margin; and epigynal shield oval, wider than long, with two pairs of setae1. In addition, metapodal shields are absent in both sexes, which is also a unique character within the Sejidae. While nearly all known members of the family have highly inflated hypostomatic setae 1 that often appear as membranous lobes, hypostomatics 1 of S. krantzi are only slightly inflated and are basically setiform. Finally, legs I have very large spiniform setae, slightly larger in females than in males. Based on its unusual suite of characteristics, and results of recently completed analyses of sejine phylogeny (Lekveishvili & Klompen, 2004; Lekveishvili & Klompen, in prep) we remove S. krantzi from Sejus and name it as the sole representative of a new genus, which we describe below. The male and immature stages will be described in a later paper. 1. The illustration of the female venter of Sejus sp. in A Manual of Acarology (12-4) shows the epigynal shield as having three rather than two pairs of setae. Since all of the specimens in the available series have only two pairs, the inclusion of a third pair in the illustration is considered to have been erroneous. SYSTEMATIC & APPLIED ACAROLOGY SPECIAL PUBLICATIONS (2004) 20 2 Adenosejus new genus Type species Sejus krantzi (S. krantzi and S. manualkrantzi (syn. nov.), sensu Hirschmann, 1991). Acarologie 38: p. 155 and p. 148. Diagnosis. With the characteristics of the family, except for the following: female with three (podonotal, mesonotal, pygidial) and male with two (podonotal, opisthonotal) dorsal shields; deutonymphs and adults with three pairs of enlarged dorsal glands, one on podonotal shield, another in the soft cuticle postero-latelral to the podonotal shield and a third pair on the pygidial (female) or opisthonotal (DN and male) shield; ventrally with one additional pair of enlarged glands on lateral margins of ventrianal shield. Protonymphs with only two pairs of enlarged glands, one on podonotal and another on pygidial shield. Metapodal shields absent. Femur-tarsus I with large spiniform setae. Protonymph without mesonotal elements. Hypostomatic seta 1 slightly inflated, setiform. Type species. Sejus krantzi (Sejus krantzi and S. manualkrantzi (syn. nov.), sensu Hirschmann 1991), by monotypy Type material. HOLOTYPE female, U.S.A.: Oregon, 20 miles southwest of Philomath, coll. G.W. Krantz, 9 May, 1958, ex fir tree hole (OSAC558-1); PARATYPES: 1 female (OSAC558-2), 3 males (OSAC558-2, OSAC558-3), 2 protonymphs (OSAC558-4), and 1 larva (OSAC558-4). Additional material examined. U.S.A.: Washington, Mtn. Foothills, Lake Olympic, 12 miles east of Quinault, coll. R.G. Mitchell, 10 Sep, 1958, ex litter (1 F, 1 M, 2 L); U.S.A.: Oregon, Mary's Peak nr. Philomath, Elev 3500', coll. G.W. Krantz, 19 June, 1957, ex forest litter (1M); U.S.A.: Oregon, Lincoln Co., 4 miles south of Waldport, coll. G.W. Krantz and J.D. Lattin, 8 Feb, 1960, ex moss (2 F, 1 DN); U.S.A.: Oregon, Mary's Peak, 0.2 miles east of Griffith Pk. Spur, coll. G.W. Krantz, 28 July, 1959, ex Hemlock tree hole (2 PN); U.S.A.: California, 44 miles north of Eureka, Redwood Hwy, coll. S. Radinovsky, 22 July, 1961, ex litter around fallen redwood (2 F, 1 M, 1 DN). Type material. Holotype female will be deposited in the collection of the National Museum of Natural History, Beltsville, MD. Paratype females, males and immatures will be placed in the Oregon State University Arthropod Collection, Corvallis, OR. Study specimens will be deposited in the Museum of Biological Diversity, Ohio State University, Columbus, and the Canadian National Collection, Ottawa. Distribution. Adenosejus krantzi has been collected only from sites in the Pacific coastal range of Oregon and California, suggesting a limited and possibly relictual distribution. Etymology. The genus is named Adenosejus (adeno-gland) because of its enlarged glands. Acknowledgement The senior author would like to thank Hans Klompen for valuable comments. References Berlese, A. (1905) Acari nuovi, Manipulus IV. Redia, 2, 154176 (Pl. IIII) Hirschmann, W. (1957) Gangsystematik der Parasitiformes. Teil 1. Rumpfbehaarung und Rckenflchen. Acarologie, Frth, 120. LEKVEISHVILI & KRANTZ: ADENOSEJUS G. N. BASED ON SEJUS KRANTZI AND S. MANUALKRANTZI 3 Hirschmann, W. (1991) Weltweite Revision der Ganggatung Sejus C.L. Koch 1836 (Trichopygidiina). Acarologie, Nrnberg 38, 107135. Hirschmann, W., Wisniewski J. & Kaczmarek, S. (1991) Weltweite Revision der Ganggatung Sejus C.L. Koch 1836 (Trichopygidiina). Acarologie, Nrnberg 38, 136214. Koch, C.L. (1836) Deutchlands Crustaceen, Myriapoden und Arachniden. fa. 4. t. 17, Regensburg. Krantz, G.W. (1978) A manual of acarology. Corvallis, Oregon, Oregon State University Book Stores, Inc., 509 pp. Lekveishvili, M. & Klompen, H. (2004) Phylogeny of infraorder Sejina (Acari: Mesostigmata). Zootaxa, 629, 119. Trgrdh, I. (1906) Neue Acariden aus Natal und Zululand. Zoologischer Anzeiger, 30, 870877. Accepted by Z.-Q. Zhang: 27 August 2004 Published: 10 September 2004 4 SYSTEMATIC & APPLIED ACAROLOGY SPECIAL PUBLICATIONS (2004) 20 ...
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