Aceria sonchi ( Nalepa, 1902 )

Knihinicki, Danuta K., Mccarren, Kathryn L. & Scott, John K., 2009, A new species of Aceria (Acari: Eriophyidae) damaging sowthistles, Sonchus spp. (Asteraceae), in Australia with notes on Aceria sonchi (Nalepa, 1902), Zootaxa 2119, pp. 23-38 : 32-34

Aceria sonchi ( Nalepa, 1902)

Generic placement and observations. When Aceria sonchi was first described by Nalepa in 1902 (no figures), he originally placed this species in the genus Eriophyes and it was later transferred to Aceria by Amrine and Stasny (1994). Nalepa (1905) supplemented his original description with further observations and included rudimentary illustrations but these were still very basic.

Translations of historical descriptions. Translations from German to English of both descriptions by Nalepa 1902 and 1905 are replicated in this paper with the kind permission of Dr Birgit Löcker (ASCU Orange, NSW, Australia). In addition, a translation of the Finnish redescription of A. sonchi by Liro and Roivainen (1951) is reproduced with the kind permission of Dr Tuomas Kostiainen (Finnish Translations, California, USA). The translations are as follows:

English translation of Aceria sonchi ( Nalepa, 1902) from original German text: “ Eriophyes sonchi n. sp. [no figure] – Body elongated, cylindrical. Shield semicircular, weakly emarginate above the rostrum. Pattern of the shield in general similar to those of related species. Tubercles of dorsal setae near the rear shield margin, far apart from each other. Dorsal setae about 1.5 times as long as the shield. Rostrum rather short, pointing forwards and downwards at the same time. Legs short, distinctly segmented/articulate. Segments almost equal in length. Featherclaw small, 5 rays. Solenidion slightly longer than featherclaw. Sternum weakly divided. Abdomen uniformly segmented (about 72 segments), even the segments situated directly in front of the caudal lobe are dorsally barely any wider. Fine, uniformous microtubercles. Lateral setae inserted behind the epigynum, almost as long as the dorsal setae. Ventral setae I about twice as long as the shield, ventral setae II about the same length as ventral setae III, but finer than those. Caudal lobe small. Caudal setae about 1/3 of body length. Accessory setae very fine. Epigynum flat, funnel-shaped. Coverflap longitudinally striped. Genital setae laterally, as long as ventral setae II. Epiandrium flat, arcuate.

Female 0.2: 0.04 mm; Male 0.17: 0.04 mm. Producing galls with solid walls, galls more or less semicircular, occurring on the upper surface of leaves of Sonchus maritimus L. Collected by Dr. K. Rechinger, Grado ( Italy).”

English translation of Aceria sonchi as re-described by Nalepa (1905) from original German text: “ Eriophyes sonchi Nal. (Plate I, Figs 3 & 4 ; see Nalepa 1905). Body elongated, cylindrical, body of females 5–5.5 times as long as wide. Prodorsal shield semicircular, weakly emarginate above rostrum [gnathosoma]. Posterior margin in between the tubercles of the dorsal setae not emarginate. Pattern of the shield (see Nalepa 1905; fig. 3, plate I) in general similar to those of related species such as E. lactucae . In the central area of the shield the three, typical, longitudinal lines are flanked on each side by a slightly outwards curved line which runs from the anterior to the posterior margin. A short branch leading to the anterior margin branches off the interior side of the “lateral” lines about mid-length. Anterior of this fork, a short curved line branches off the exterior side of the main line. This outwardly curved line ends at the tubercles of the prodorsal setae. Parallel to this line and above this line there are also some other short curved lines visible in the lateral parts of the shield, but their exact path cannot be detected due to the strong concavity of the shield and seems to vary. The tubercles of the prodorsal setae are far apart from each other and situated near the rear shield margin. The dorsal setae are directed caudally. They are about 1.5 times as long as the shield.

Rostrum very short (0.022 mm), slightly curved, pointing forward and downward at the same time. Setae of rostrum, strongly developed.

Legs short, distinctly segmented/articulate. Segments of leg rather short, almost equal in length. Interior setae and tibial setae of the second pair of legs, fine and short. Femoral setae of both pairs of legs rather long. Featherclaw [empodium] small, with 5 rays. Solenidion slightly longer than featherclaw. Striations on coxae shortened. Exterior striations slightly extended. Sternum distinctly divided in well-cleared specimens. The coxal setae of the 1st pair of legs inserted somewhat slightly posterior to the anterior margin of the sternum. The coxal setae of the 2nd pair of legs inserted somewhat slightly anterior to the interior striations of the coxae.

Abdomen [opisthosoma] in general, uniformly cylindric, tapering only in the posterior quarter. Segmentation uniformous (about 72 annuli); even the segments [annuli] directly in front of the caudal lobe are dorsally barely any wider. Fine, uniformous microtubercles. Lateral setae inserted posterior to the epigynum [female genital coverflap]; lateral setae almost as long as prodorsal setae. 1st pair of ventral setae about twice as long as shield; 2nd pair of ventral setae about as long as the 3rd pair of ventral setae, but very fine. The 1st pair of ventral setae inserted rather anterior. Caudal lobe, small. Caudal setae rather short, about 1/3 of the body length, fine. Accessory setae pen-shaped, thickened, not reaching the posterior margin of the caudal lobe.

Epigynum flat, funnel-shaped, 0.022 mm wide. Coverflap longitudinally striped. Genital setae near margins, fine, about as long as the 2nd pair of ventral setae.

Epiandrium flat, arched, 0.017 mm wide.

Average body length of female: 0.2 mm; average body width of female: 0.04 mm. Average body length of male: 0.17 mm; average body width of male: 0.04 mm.

Eriophyes sonchi differs from E. lactucae in having a slightly different pattern of the shield (see Fig. 9, plate I, Nalepa, 1905), in a less emarginate anterior margin of the shield and in the non-emarginate posterior margin of the shield, in the distinctly separated tubercles of the prodorsal setae, mainly also in having shorter claws [solenidia], caudal and lateral setae and finally in having the exterior striations of the coxae in a rather posterior (basal) position.

Eriophyes sonchi produces galls on Sonchus maritimus L. These galls are irregularly shaped with solid walls. The galls occur singularly or in groups on both surfaces of the leaf, mainly near the margins. Sometimes, they are found in small numbers on the sepals and shafts of flowers. The large cavity of the gall has a small opening, which is usually situated at the top of a conical elevation on the upper or lower surface of the leaf. The galls lack setae/hairs. The galls are initially green and turn red to yellow in later stages. They are 2–5 mm in diameter (see Stefani Perez, Note cecidologiche, in Marcellia, 1903, II, 5 p. 106, Nr 23). Dr K. Rechinger found the above noted cecidium of Sonchus maritimus L. near Grado.”

English translation of Aceria sonchi as re-described by Liro and Roivainen (1951) from original Finnish text: “ Eriophyes sonchi Nal. 1904 , [correct publication date of original description by Nalepa is 1902] p. 133. Valvatin rengaspunkki [= Finnish common name for E. sonchi ] (Figure 52, 6; see Liro & Roivainen 1951). Body cylindrical. Shield is triangular with a concave end; a cone pattern formed by three lines in the central field, and on both sides of this is a shorter line and a longer line originating from the anterior margin, the longer line branches out from its middle part to the sides; a third longitudinal line occasionally on the outer margins of the lateral fields; tubercles located far apart, on posterior margin laterally to them are a couple of pieces of a ring; setae about one-and-half times as long as the shield. Rostrum normal. Legs delicate; featherclaw 5-rayed. Coxal sternum, forked. Number of rings about 72; accessory setae short. Male 170 x 40 μm; Female 200 x 40 μm.

Lives in solid-surfaced galls of leaf flesh of Sonchus arvensis var. maritimus Wahlenb. Gall opening in a small protrusion on an upper or lower leaf surface. Galls are first greenish but soon become reddish; their diameter is 2–3 mm. Northern Spain.”

Remarks about historical descriptions of Aceria sonchi . The supplementary description by Liro and Roivainen (1951) is similar to the original descriptions of Aceria sonchi that were provided by Nalepa (1902 and 1905) in terms of the general pattern of the prodorsal shield, body length and width as well as number of rays on the empodia. A difference is that the galls as measured by Liro and Roivainen (1951) were slightly smaller (2–3 mm in diameter) compared with those documented by Nalepa (1905) which were 2–5 mm. Nalepa (1902 & 1905) noted A. sonchi as occurring on S. maritimus whereby Liro and Roivainen (1951) listed the host plant as S. arvensis var. maritimus . It is likely that the later refers to S. maritimus .

Distribution of Aceria sonchi . This species has been listed in several catalogues: Amrine and Stasny (1994); Davis et al. (1982); Nalepa (1923); Nalepa (1929); and Newkirk (1984). Its recorded geographical distribution is Algeria ( Houard 1922), Italy including Sicily ( Nalepa 1902, 1905; De Stefani Perez 1903; Cecconi 1904, 1906; Bernini et al. 1995); Libya ( Trotter 1912), Morocco ( Houard 1921, 1922), Spain ( Liro & Roivainen 1951) and Tunisia ( Houard 1922). Apart from these early records of A. sonchi , no other sightings are known (Enrico de Lillo, pers. comm., 2007 to J. Scott).

Aceria sonchi was originally found on Sonchus maritimus Wahlenb. which is known as its type host ( Nalepa 1902, 1905, 1929; De Stefani Perez 1903; Cecconi 1906; Trotter 1912; Houard 1921, 1922; Buhr 1965; Sukhareva 2001). The mite has also been recorded from S. arvensis L. ( Buhr 1965), S. arvensis var. maritimus Wahlenb. ( Liro & Roivainen 1951) , and S. maritimus L. var. augustifolius Bisch. ( Houard 1909) . The early literature indicated that A. sonchi produces conspicuous, rounded galls or pustules on the plant surfaces which have a small opening (ostiole) ( Nalepa 1902, 1905; Houard 1909, 1922; Trotter 1912; Liro & Rovainen 1951; Buhr 1965; Sukhareva 2001).

Remarks about type material of Aceria sonchi . With relation to the original specimens of A. sonchi as described by Nalepa (1902, 1905), a vial presumably containing type material of this species was borrowed from the Natural History Museum, Vienna, Austria, for further investigation. As expected the 100 year old contents were found to be severely degraded. A hand-written note placed inside the vial bears collection details (host plant and locality) along with a small amount of viscous, almost granular sediment that has adhered to the bottom and sides of the vial. So far, it has not proved possible to retrieve specimens. Another attempt to salvage specimens from this material will be undertaken as part of a later study (using methodology as advised by J. Amrine Jr. pers. comm. 2008). The aim would be to designate a lectotype for A. sonchi from this original material (if syntypes are present) because the holotype of A. sonchi is unknown. If this is not possible, designation of a neotype may be achievable if additional fresh specimens of A. sonchi are rediscovered from the original type locality and type host plant.

Figures

FIGURE 3. Aceria thalgi sp. n. SA Lateral view of anterior region of female; ES Lateral view of dorsal and ventral annuli region. API Apodeme of internal female genitalia; GF Coxigenital region of female; GM Coxigenital region of male; L 1 Lateral view of Leg I; L 2 Lateral view of Leg II; E Tarsal empodium and solenidion.

FIGURE 4. A – D Light micrographs of Aceria thalgi sp. n. as viewed under 100 X oil immersion. A Prodorsal shield of female; B Coxigenital region of female; C Prodorsal shield of male; D Coxigenital region of male. Scale bar = 10 μm.