Chronogaster africana Heyns & Coomans, 1980

Girgan, Chantelle, Marais, Mariette, Fourie, Hendrika, Tiedt, Lourens & Swart, Antoinette, 2019, Description of two new species, Aphanolaimus strilliae n. sp. (Nematoda: Aphanolaimidae) and Makatinus africanus n. sp. (Nematoda: Aporcelaimidae), and SEM observations on three known species from freshwater sources in the Telperion Nature Reserve (Mpumalanga, South Africa), Zootaxa 4651 (2), pp. 201-234 : 216-217

Chronogaster africana Heyns & Coomans, 1980

Figures 9 & 10

Measurements: Table 4

The female specimen was identified as Chronogaster africana based on morphometrics and morphology, especially the morphology of the tail terminus displaying a mucro with six short spines, and the absence of no crystalloids in the body cavity. The female specimen found in Telperion Nature Reserve (no males found) matches that of the original description by Heyns & Coomans (1980) with only difference being the length of the post-uterine branch (12.5 µm vs 6–9.5 µm). First time SEM observations on this species revealed the following: Lip region three annules long with four cephalic setae and amphid openings on second annule with their posterior margins protruding slightly. Amphid aperture with two protrusions towards inside. Cuticle shows distinct annules, no lateral field. Excretory pore located 140 µm from anterior end its opening one body annule wide. Lateral caudal pore on tail 30 µm posterior from anus on lateral side of body. This pore indicates two openings, one in the anterior and one in the posterior margin ( Figure 10 B ). Tail terminus consists of six small projections on the base of one larger mucro. In some instances, an extra projection noticed on larger mucro ( Figure 10 C–F). Annules at the base of the tail tip showed some anastomoses / breaks in striations on lateral sides ( Figure 10 F ).

Discussion. Chronogaster africana was first described in South Africa in 1980 from water sediment samples in Boskop Dam and The Kloof (North West Province), Natalspruit (Gauteng Province), and Krom River (Western Cape Province). It was then again reported in South Africa in 1992 from sand near the weir in the Sabie River near Lower Sabie (Mpumalanga Province) ( Botha & Heyns 1992). As this species has been reported in this country only, it is considered endemic to South Africa.

Locality and material examined: In the Telperion Nature Reserve a female specimen of C. africana was collected at the Wetland site ( Table 1 ) with locality number MP00043 and deposited in the National Collection of Nematodes (ARC—Plant Health and Protection, Biosystematics, Pretoria) on slide number 50567.

Figures

FIGURE 9. Scanning electron micrograph of Chronogaster africana Heyns & Coomans, 1980 female, A) Anterior end showing cephalic setae (cs) and amphid opening (a); B) Ventral side of body showing cephalic region with cephalic setae (cs) and amphid (a); C) Close up of excretory pore (exp); D) Anterior region showing the position of the excretory pore (exp).

FIGURE 10. Scanning electron micrograph of Chronogaster africana Heyns & Coomans, 1980 female, A) Posterior end showing anus and arrow indicating caudal pore; B) Close up of caudal pore arrows indicating two possible openings; C, D, F) Tail tip showing projections, arrows indicate anastomosis; E) Posterior end indicating anus and caudal pores (arrow).

Tables

TABLE 4. Morphometrics of a single female of Chronogaster africana Heyns & Coomans, 1980 found in freshwater substrates in the Telperion Nature Reserve.

Morphometric feature	n = 1
L	1661
L’	1465
a	68.7
a’	60.6
b	6.2
c	8.2
c’	10.4
V%	50
G1 %	9
Body width at anus	19
Body width at mid body	24
Body width at vulva	26
Annule width at neck region	1
Annule width at base of oesophagus	2
Annule width at mid body	2
Annule width opposite anus	2
Annule width on tail	1
Lip region height	5
Lip region width	9
Cephalic setae length	7
Stoma length	11
Stoma width	3
Radial tubules from base of stoma	23
Excretory pore from anterior	153
Basal bulb length	27
Basal bulb width	17
Oesophagus length	269
Postbulbar extension	16
Cardia length	–
Vagina length	9
Length of anterior genital tract	153