Tritogenia hiltonia, Plisko, 2003

Plisko, Jadwiga Danuta, 2003, Eleven new South African earthworms (Oligochaeta: Microchaetidae) with new information on some known species, and an inventory of the microchaetids of KwaZulu-Natal, African Invertebrates 44 (2), pp. 279-325 : 312-314

Tritogenia hiltonia sp.n.

( Fig. 16 )

Etymology: Named after the name of the type locality, Hilton.

Material examined: KwaZulu­Natal: Holotype NMSA /Olig.03534 Hilton College (29º30'48"S: 30º18'03"E) at 1119 m, Mistbelt grassland, with many flowering herbs, collected 2–30 cm between roots of various plants, 13 December 2001, AJA, HM. Paratypes: NMSA /Olig.03644, 7 cl, collected together with holotype. Other material: NMSA /Olig.03645, 12 juv and NMSA /Olig.03646, 2 cocoons collected with holotype. Hilton College (29º30'47"S: 30º18'02"E) at 1109 m, medium­tall grassland with many herbs, dry soil, at ca. 30 cm, 22 January 2002: NMSA / Olig. 03546, 1 cl and NMSA / Olig. 03547, 4 juv. All material collected by AJA, HM. Cedara (29º32'S: 30º17'E) experimental agricultural field, sample 1 and 2: NMSA / Olig. 02856 and NMSA / Olig. 02857, 1 juv and 2 semi­mature, 25 February 2000, R. J. Haynes .

Description based on holotype and paratypes.

External characters:

General: body cylindrical, compact after preservation. Colour: grey in life, preserved in formalin whitish­grey. Dimensions: preserved and contracted holotype 56 mm long, 4 mm wide at 10, 5 mm at tubercula pubertatis; clitellate paratypes 38–56 mm long, 4– 6 mm wide; juvenile 28–40 mm long. Segment number: holotype 90; paratypes 70–97. Prostomium: prolobous, not clearly separated from first segment. Segmentation: secondary annulation present on preclitellar segments; 1–3 simple, with irregular longitudinal grooves; 4–8 with 2 simple ringlets, similar in size and appearance; 9 with 2 ringlets, second shorter than first; segment 10, clitellar and postclitellar simple. Setae: minuscule, closely paired, in irregular rows; in preclitellar segments difficult to trace; postclitellarly ab closely paired in slightly irregular, longitudinal rows, cd sporadically observed only in some segments. Nephridial pores: not observed. Female pores: paired, minute openings in anterior part of segment 14. Male pores: externally not observed; probably in intersegmental furrow 19/20, where are small swellings. Spermathecal pores: conspicuous externally in intersegmental furrows 11/12 and 12/13; one or two small pores with round swellings.

Clitellar region ( Fig. 16 ): Clitellum: saddle­shaped, segmented, whitish­grey; on holotype on 13–23; on 13–17 clitellar tissues developed only dorsally; on 18–23 ventral edges extend to dorsal borders of tubercula pubertatis. Tubercula pubertatis: on 18–22 between ventral edges of clitellum and median line; nearly square glandular swellings, randomly grooved by irregular shallow furrows; ventrally on 21–22 separated medially by narrow triangle invagination; on 17 rounded single swelling above groove separating tubercula. Papillae: on 10–14, paired or single, round swellings around ab or cd setae. Internal characters:

Septa: 4/5 little thickened, 5/6 6/7 thickened very much, muscular, similar in thickness and appearance; 7/8 8/9 thickened less than anterior; 9/10 aborted; other septa in preclitellar segments thin; in posterior segments slightly thicker. Gizzard: large, muscular, in 6; commencing abruptly at septum 5/6 extends and occupies whole of 6, terminating abruptly at septum 6/7. Calciferous glands: in 9–10, stalked; separated widely ventrally, dorsally by short distance. Stalks extend along the whole length of calciferous glands. Intestine: commences in 13. Typhlosole: commences in 16, slim, V­shaped; in following segments gradually enlarging, becoming square, medially furrowed; terminates in area of 54. Dorsal blood vessel: double in 4–11; double when crossing septa 4/5–10/11; in 12 slightly enlarged, simple; in following segments simple. Paired dorsoventral commissural vessels: 4–8 thin, gradually enlarging; 9–11 thick, moniliform. Nephridia : in posterior segments two pairs; ventral pairs close to median body line, second pairs dorsally. Spermiductal funnels: holandric arrangement; two pairs similar in size and appearance, in 10 and 11 respectively; each pair enclosed in separate sac connected with vesiculae seminales; in dissected holotype sperm was observed in all funnels. Seminal vesicles: two pairs of small sacs in 10 and 11 respectively; one pair per segment, each linked with testis sacs at septa 10/11 and 11/12 respectively. Spermathecae: in 12 and 13, iridescent; 1–2 at each side; irregular in shape, thin, elongated with slightly enlarged ampullae; close to genital glands 12 and 13. Ovaries: paired, in 13, large, funnel­like. Genital glands: paired; in 12–15 small, flat, round; in 21 finger­shaped, elongated, 3–4 branched.

Biological notes: Found between roots of various plants at depth 2–30 cm. Several individuals at different stages of development and two cocoons were present in the same sample. Sperm observed in the spermiductal funnels and spermathecae confirm breeding activity during summer.

Distribution: Known only from the type locality in the area of Pietermaritzburg ( Fig. 14 ).

Discussion: The species belongs to the sulcata species­group having spermathecal pores in two intersegmental furrows 11/12 and 12/13. Similar to sulcata but distinguished by the position and shape of tubercula pubertatis, the number and position of genital papillae, and the arrangement of setae.

Figures

Fig. 16. Tritogenia hiltonia sp. n., holotype, anterior part of the body ventrally, showing secondary annulation of segments 4–9, and tubercula pubertatis.

Fig. 14. The distribution of Tritogenia species in KZN. 1 = alveata; 2 = annetteae; 3 = ataxia; 4 = benhami; 5 = crassa; 6 = curiosa; 7 = curta; 8 = debbieae; 9 = diversa; 10 = douglasi; 11 = herbana; 12 = hiltonia; 13 = howickiana; 14 = insolita; 15 = karkloofia; 16 = koilia; 17 = liversagei; 18 = lunata; 19 = melmothana; 20 = miniseta; 21 = monosticha; 22 = morosa; 23 = mucosa; 24 = ngelensis; 25 = ngomensis; 26 = qudeni; 27 = shawi; 28 = soleata; 29 = sulcata; 30 = tetrata; 31 = zuluensis.