Aporcelaimellus salsus, Andrássy, 2010

Andrássy, I., 2010, Two New Species Of Aporcelaimellus (Nematoda: Dorylaimida) From The Americas, Acta Zoologica Academiae Scientiarum Hungaricae 56 (1), pp. 1-8 : 2-5

Aporcelaimellus salsus sp. n.

( Fig. 1 A–G )

Holotype female. L = 1.54 mm; a = 25; b = 3.7; c = 35; c’ = 1.3; V = 52 %.

Paratype females (n = 4). L = 1.57–1.88 mm; a = 24–26; b = 3.7–3.9; c = 35–44; c’ = 1.2–1.3; V = 46–52 %.

Type specimens. Holotype female on slide No. 15001 . Paratypes: three females and two juveniles. They will be deposited at the zoological collection of the Hungarian Natural History Museum , Budapest .

Type habitat and locality. Soil in a cherry orchard on the southern shore of Great Salt Lake , Utah, United States; collected in September 1992 by A. FODOR ( Wooster , Ohio, USA) .

General characters. Body moderate in size, robust, more or less ventrally curved upon fixation, 61–66 µm wide at its middle region. Cuticle smooth, 2.2–2.8 µm thick on most part of body, and 5–7 µm thick on tail, consisting of the usual two layers of different refraction. Both layers are nearly equally thick on the anterior half of the body, but the inner layer becomes thicker on the posterior region, particularly on the tail. Body pores only in the neck region conspicuous, in other regions obscure. Lip region 19–20 µm wide, offset by a deep constriction, lips large, rounded and separated. Body at posterior end of pharynx 3.1–3.6 times as wide as head. Amphids cup-shaped, half as wide as corresponding body width. Lacuna on neck between cuticle and longitudinal muscle band practically absent.

Odontostyle relatively short, 18–19 µm, nearly as long as labial diameter, aperture occupying three-fifths spear length. Guiding apparatus aporcelaimoid. Pharynx strong, 412–432 µm long, expanded near its middle. Dorsal pharyngeal gland nucleus located at 59–61% of pharynx length or 15–16% of entire length of body. Other nuclei rather inconspicuous; in one female they are located as follows: AS 1 = 20%, AS 2 = 32%, PS1 = 66% and PS2 = 68%. Glandularium 164–170 µm long .

Female. Amphidelphic with genital branches 2.6–3.2 body widths long or occupying 11–13% of body length each. Anterior branch situated on the right, posterior on the left side of intestine. Vulva a transverse slit with unsclerotized inner lips. Vagina 24–26 µm long, occupying about 40% of corresponding body diameter. Uterus a simple tube; uterus–oviduct junction marked by a sphincter. No uterine eggs observed. Prerectum 3.0–4.5, rectum 1.2–1.3 anal body widths long. Vulva–anus distance equal to 16–23 tail lengths. Tail somewhat longer than anal body width, conical with narrowly rounded tip, 36–46 µm long; its ventral contour straight or slightly convex, its dorsal contour slightly convex. On the tip of the tail, the thin outer layer and the thicker inner layer of the cuticle are separated from each other, and surround a small but distinct lacuna.

Male. Not found.

Diagnosis and relationships. A medium-sized Aporcelaimellus species with short odontostyle, pharynx expanded at the mid-region, unsclerotized vulva, relatively long prerectum, conical, dorsally slightly convex tail, and with separated cuticle layers on the tip of tail. Especially the unsclerotized vulva and the shape and structure of the tail characterize this species.

On the basis of the tail shape, the members of the genus Aporcelaimellus may be divided into two large groups: species where the dorsal contour of the tail is concave at least near its tip, and those where the dorsal contour is straight or more or less convex (never concave). The new species belongs to the second group. According to the key to Aporcelaimellus species by ANDRÁSSY (2002), there are three species in that group which possess an odontostyle shorter than 30 µm as well as an unsclerotized vulva: A. adriaani BOTHA et HEYNS, 1990 , A. papillatus ( BASTIAN, 1865) BAQRI & KHERA, 1975 and A. parapapillatus BOTHA et HEYNS, 1990 . Aporcelaimellus salsus sp. n. can be differentiated from all of them by having strongly separated cuticle layers on tail tip. Furthermore, it differs from A. adriaani by the longer body (1.5–1.9 vs 1.2–1.5 mm), wider lip region (19–20 vs 12–15 µm), longer odontostyle (18–19 vs 14–16 µm), and by the tail longer than one anal body diameter (c’ = 1.2–1.3 vs 0.9–1.1, or 36–44 vs 21–30 µm). It differs from A. papillatus (as redescribed by THORNE & SWANGER 1936, and DE BRUIN & HEYNS 1992) by the shorter body (1.5–1.9 vs 2.1–2.8 mm), wider lip region (19–20 vs 15–17 µm), longer odontostyle (18–19 vs 14–16 µm) and longer tail (c’ = 1.2–1.3 vs 0.8–1.0, or 36–46 vs 24–33 µm). Finally, it differs from A. parapapillatus by the shorter (1.5–1.9 vs 2.1–2.8 mm) and thinner body (61–66 vs 65–83 µm) and longer tail (c’ = 1.2–1.3 vs 0.8–1.0).

Another species, Aporcelaimellus proximus ( THORNE et SWANGER, 1936) LOOF and COOMANS, 1970 should be mentioned. Quite recently, ÁLVAREZ- ORTEGA and PEÑA- SANTIAGO revised some Aporcelaimellus species described by THORNE and SWANGER in 1936. Although their paper is still under printing and will appear in the next year (2010), the authors gave me permission to compare my Aporcelaimellus salsus sp. n. with the above-mentioned A. proximus as revised by them. They studied specimens of the collection of THORNE labelled “Provo, Utah ” as locality, meanwhile the American authors mentioned “Salem, Utah ” as type locality. (These two cities are at a distance of about 25 km from each other.) Therefore, it is possible that the specimens investigated by the Spanish authors did not come from the type population (of the type locality). The matter becomes more complicated by that TJEPKEMA, FERRIS and FERRIS (1971) already studied Aporcelaimellus proximus specimens of THORNE’ s collection originated from “Salem, Utah ”, the type locality. Well, the animals of TJEPKEMA and co-authors and those of ÁLVAREZ- ORTEGA and PEÑA- SANTIAGO differed in one important structure from each other: “Vulval labia with triangular sclerotized pieces” (by TJEPKEMA et al. 1971), respectively, “Pars refringens (= vulval labia in the former sense) not well differentiated, lacking any distinct sclerotization” (by ÁLVAREZ-ORTEGA & PEÑA- SANTIAGO). Supposing that both observations were correct, the specific identity of the “Provo” and “Salem” populations appears to be somewhat uncertain.

The present new nematode, Aporcelaimellus salsus sp. n. resembles the “two” species in both measurements and several morphological characters. However, it clearly differs from the typical A. proximus as characterized and/or illustrated by THORNE and SWANGER as well as TJEPKEMA et al. in having unsclerotized vulval labia and special structure of the tail and caudal cuticle. On the other hand, it is not impossible that the animals of ÁLVAREZ- ORTEGA and PEÑA- SANTIAGO with unsclerotized vulval labia are conspecific with A. salsus sp. n. Only the caudal structures of them seem to be different. This question remains unsettled for the moment.

Etymology. The species epithet salsus (Latin) means salty or salted, and refers to the type locality, Great Salt Lake in Utah, United States.

Figures

Fig. 1. Aporcelaimellus salsus sp. n.: A = anterior end, B = cardial region, C = vulval region, D = female posterior end, E–G = female tail variations. (Scale bars 20 µm each)