Aphelenchoides rutgersi Hooper & Myers, 1971

Girgan, Chantelle, Swart, Antoinette, Marais, Mariette & Fourie, Hendrika, 2018, Aphelenchoides spp. (Nematoda: Aphelenchida) and Panagrolaimus leperisini (Nematoda: Rhabditida) found associated with grass seeds in the Telperion Nature Reserve, South Africa, Zootaxa 4370 (2), pp. 137-155 : 145-146

Aphelenchoides rutgersi Hooper & Myers, 1971

( Fig. 3 & 4 )

Aphelenchoides rutgersi was originally collected by W. Feder from around citrus roots Orlando, Florida, U.S. A and described from specimens cultured on Setophoma terrestris (H.N. Hansen) Gruyter, Aveskamp & Verkley or Botrytis cinerea Pers. ( Hooper & Myers 1971) . This species was then again found in the rhizosphere of tobacco plants in Bulgaria ( Katalan-Gateva & Budurova, 1976).

Measurements. See Table 4.

Description. Female: (n = 3) Habitus slightly curved ventrally. Cuticle finely annulated, annule width about 1 µm at mid-body. Lateral field 3–4 µm wide marked with three incisures ( Fig. 3D ). Head slightly offset ( Fig. 3A ). Lip region 2–4 µm high and 3–4 µm wide. Stylet 11–12 µm long with slight basal thickenings. Median bulb spherical with centrally located valve ( Fig. 3A ). Nerve ring situated 66–68 µm from anterior end, less than one corresponding body width from base of median bulb. Excretory pore 75–76 µm from anterior end, opposite nerve ring ( Fig. 3A ). Ovary outstretched with a single row of oocytes ( Fig. 3B ). Spermatheca elongate, containing sperm cells ( Fig. 4A ). Vulval lips slightly protruding with the vagina occupying about half the corresponding body width, curving anteriorly ( Fig. 3C ). Post-vulval uterine sac 37–43 µm in length, about 2.5 times vulval body width and shorter than half vulva-anus distance ( Fig. 3C ). Tail elongate conoid, 33–37 µm long. Terminus bearing a short, slightly ventrally-located mucro ( Fig. 3E–G & 4B ).

Male: Not found.

Discussion. The female specimen of the Aphelenchoides sp. found associated with the seeds of Aristida canescens collected from the Telperion Nature Reserve were identified as A. rutgersi based on tail shape and morphological characteristics matching those of Hooper & Myers (1971). There were only the following differences: Spermatheca and sperm cells observed in South African specimen. In the original description, spermatheca were indistinct and contained no sperm cells. However, males are present in this species and the presence of sperm cells is possible. This species is reported for the first time in South Africa and to our knowledge, it is the second report since its description. Specimens were deposited in the NCN under accession number 50541.

Relationships. The Aphelenchoides specimens from Aristida cansescens were compared with species that are morphologically similar to the South African specimens in having a tail with one or two terminal mucronate structures and three incisures in the lateral field. Comparing the morphological and morphometric data of our Telperion specimens to those in Shahina’s (1996) compendium, the following species with a relatively long postvulval uterine sac (PUS) can be differentiated from A. rutgersi (PUS less than half the vulva-anus distance): A. agarici Seth & Sharma, 1986 , A. minoris Ebsary, 1991 , and A. myceliophagus Seth & Sharma, 1986 all have a PUS more than half the vulva-anus distance.

Some of the smaller species also differ based on shorter body length (542–582 µm in A. rutgersi ): A. breviuterallis Eroshenko, 1968 (L = 410–460 µm) also has a shorter stylet (8 µm compared to 11–12 µm in A. rutgersi ); A. cibolensis Riffle, 1970 (L = 360–460 µm) with a shorter tail (27 µm compared to 33-37 µm in A. rutgersi ); while A. trivialis Franklin & Siddiqi, 1963 (L = 360–490 µm) has a reflexed ovary compared to no flexure in A. rutgersi . A. curiolis Gritsenko, 1971 has a significantly shorter stylet (6 µm compared to 11–12 µm in A. rutgersi ). A. chamelocephalus ( Steiner, 1926) Filipjev, 1934 differs in the more posterior position of the vulva: 75–80% compared to 69–70% in A. rutgersi .

The species most morphologically similar is A. swarupi Seth & Sharma, 1986 and differs only in having a higher c’ value (5 compared to 3–4 in A. rutgersi ). Other closely related species based on morphology are A. eltayebi Zeidan & Geraert, 1991 and A. sacchari Hooper, 1958 . Aphelenchoides eltayebi differs in having a more offset head and a more anterior excretory pore (44µm from anterior vs. 76µm in A. rutgersi ). Aphelenchoides sacchari differs in having oocytes arranged in two rows at the anterior end of the ovary (only one row in A. rutgersi ).

Figures

FIGURE 3. Aphelenchoides rutgersi, female. A: Anterior region; B: Anterior end of reproductive system showing arrangementof oocytes C: Vulval region showing post-vulval uterine sac D: Lateral field at mid-body; E–G: Tail region.

FIGURE 4. Aphelenchoides rutgersi, female. A: Vulval region showing spermatheca with arrows indicating sperm cells; and post-vulval uterine sac; B: Tail region.