Tritogenia zuluensis ( Beddard, 1907 )

Plisko, Jadwiga Danuta, 2013, The role of museums in safeguarding biodiversity: A happy end of the century-long saga of Tritogenia zuluensis (Beddard, 1907) (Oligochaeta: Tritogeniidae), African Invertebrates 54 (2), pp. 477-477 : 479-483

Tritogenia zuluensis ( Beddard, 1907)

Figs 1–4

Microchaetus zuluensis: Beddard 1907: 279 .

Microchaetus zulu: Michaelsen 1907: 6 .

Microchaetus zuluensis [partim]: Michaelsen 1913: 436; 1918: 331; 1928 a: 6.

Tritogenia zululensis [lapsus calami for zuluensis ] [partim]: Plisko 1992: 373.

Tritogenia zuluensis [partim]: Plisko 1997: 278; 2006: 34; 2008: 101; 2013: 69, 77.

Non Microchaeta zuluensis: Coles 1981: 299 .

Non Microchaetus zuluensis Michaelsen, 1907 [sic] for Microchaetus zuluensis Beddard, 1907 sensu Reynolds & Cook 1976: 192 .

Diagnosis: Holandric. Two pairs of seminal vesicles, with posterior pair slightly smaller than anterior pair. Excretory system meroic; small number of nephridia, very difficult to find. One oesophageal gizzard in 6–7, with septum 6/7 attached at ⅓ part of gizzard. Dorsal blood vessel double in segments 4–10 and when crossing septa, in 12 and the following segments broader, simple. Spermathecae difficult to locate, multiple in segments 11–15. Septa much thickened in 4/5 and 5/6–8/9. Setae small, at anterior part of the body difficult to discern, eight posteriorly, paired in four rows.

Description:

External characters (preserved material slightly decomposed): Grey with minor brownish colouration. Body in life probably plump, at present softened and extended. Dimensions: Abscised part of clitellate lectotype> 70 mm long, 10 mm wide at 10, 14 mm in region of tubercula pubertatis.Anterior fragment of semi-mature paralectotype> 130 mm long. Complete specimens probably ca 120–180 mm long, as is observed in synonymic material. Segment number: Anterior body fragments: lectotype>86, paralectotype>109 (complete segment number unknown, possibly around 130 segments; other material ca 138). Prostomium: Small, zygolobous. Segmentation: Secondary annulation present; 1–3 simple, first and second with irregular annulation, longitudinally grooved; third smooth; 4–10 with 2 simple ringlets, similar in size ( Figs 2, 4 , 5 ); 11 and those that follow simple, ventrally irregularly annulated; postclitellar segments simple, randomly annulated. Nephridial pores: Not observed. Female pores: Not detected externally.

Male pores: Not detected externally and internally. Spermathecal pores: Not observed, although Michaelsen (1907) noted them in the 5 intersegmental furrows 11/12–15/16. Clitellum ( Figs 2, 3 ): Brownish grey; saddle-shaped, clearly segmented, on ⅓14–28); ventral borders terminate parallel to dorsal edges of tubercula pubertatis. Tubercula pubertatis ( Fig. 2 ): Glandular, elongated flat tubercles; on lectotype at 16–22 below clitellar edges, extending to middle of the body, separated by narrow segmented field; on paralectotype less developed, on 17–21. Papillae ( Figs 2, 4 , 5 ): Variable in size, shape and location, paired or single swellings in ab setal lines; on lectotype large, paired on 10, smaller on 11–14, on 22–26 prominent, some with genital setae. On paralectotype single on 11, paired on 12, prominent and paired on 23–26, some with genital setae. On other specimens on 11, 12 and sometimes 21–26.

Internal characters: Septa ( Figs 3 , 6 ): 4/5 slightly thickened, 5/6–8/9 markedly so, similar in appearance; 9/10 very thin, partly aborted; other septa in preclitellar segments thin; in posterior segments somewhat thicker. Gizzard ( Fig. 6 ): Oesophageal, large, muscular, commencing in 6, extends and occupies whole of 7, terminating abruptly at septum 7/8. Calciferous glands (difficult to see in type material; not present in comparative material, having been removed by Michaelsen (1918: 331–332) for a study with its particular description): Half-globular in 9–10; closely connected to oesophagus; dorsally and ventrally separated. Intestine ( Fig. 3 ): Commences in 12 in lectotype (it is difficult to see where the origin of the intestine is due to desiccation). Typhlosole: Commencement not detected. Dorsal blood vessel: Double in 5–10 and also when crossing septa 4/5– 10/11; in 12 and the segments that follow, broader and simple. Paired dorso­ventral commissural vessels: In 4–8, slender tubes; in 9–11, thick moniliform ‘hearts’. Excretory system: Meroic; minute mero-nephridia difficult to detect between fragile, decomposing internal tissues, so their exact number and position were not established; two tiny pairs possibly occur in each segment, as was found in a few postclitellar segments of type material. (Obvious meroic pairs observed in anterior segments in material described by Michaelsen (1907) were mistakenly interpreted: ‘ Nephridialsystem meganephridisch ’ [excretory system meganephridial], which means a holoic system.) Male funnels: Two pairs of funnels, indicating holandric nature of this species, and not proandric as is stated by Beddard (1907: 281) and Michaelsen (1907: 8); the first pair much larger than second, both closely connected with seminal vesicle. Vasa deferentia: Not detected due to internal dryness and slight decomposition of specimens. Seminal vesicles: Two pairs, second being much smaller than the anterior pair, in 10 and 11 respectively, both linked with testis sacs. Spermathecae: Spermathecal ampullae were not observed in type material by Beddard (1907), possibly because of their small size, and perhaps emptiness; being uninseminated, these structures were difficult to trace amongst the thick, slightly decomposed body tissues. Some tiny remnants of the ampullae that were seen at 350× magnification in segment 13, suggest their possible presence in other segments as well. In a specimen collected by I. Trägårdh in Umfolozi, close to the type locality, two to eleven spermathecal ampullae are present, near intersegmental furrows 11/12–15/16. Ovaries: In 13; one funnel-like, near septa 13/14. Genital glands: Variable in size and shape, associated with genital papillae. Genital setae: Noted once in genital gland of 22 nd segment.

Type material and locality: Lectotype (NHMU Oslo C5726) and paralectotype (NHMU Oslo C5727) originated from ‘Zulu-Land’, the area north of the Thukela River in north-eastern KwaZulu-Natal, South Africa. Unfortunately, no additional data concerning the collection site were given. It was probably in the vicinity of where Proandricus colletti ( Beddard, 1907) (Plisko 2000) was collected by Knut Dahl during his hunting expedition to Zululand in 1893–1894 ( Dickison 1951; Pethon 2009), and likely the same as what was known at that time as Umfolozi Game Reserve, which was visited by various hunters and researchers.

Other material was collected by Swedish researcher Ivor Trägårdh on 6 June 1905, in ‘Zulu-Land, Umpolozi’ (Michaelsen 1907), probably close to the type locality of zuluensis but described by Michaelsen as ‘ Microchaetus zulu ’, which he later accepted as a synonym of Microchaetus zuluensis . The present study indicates that this type specimen (GNM Oligochaeta 16), should now be known as Tritogenia zuluensis ( Beddard, 1907) .

Distribution: The species is so far known from the Hluhluwe-iMfolozi Nature Reserve in the KwaZulu-Natal Province of South Africa.

Remarks: The type material of T. zuluensis was probably collected in the southern part of the Hluhluwe-iMfolozi Park which, before its proclamation in 1895 as a National Park, was a hunting area named Umfolozi. The area covers over 50,000 ha of magnificent foothills of the first escarpment rising from the coastal plain, with the two main rivers, the Black and White Mfolozi, joined by a number of streams. Erosion over millions of years have resulted in a variety of soils with many endemic plant and animal species, and some earthworm material was sporadically collected in the region.

Michaelsen’s zulu ( Figs 5–7 ) was from this area, with the name incorrectly printed as ‘Umpolozi’. The original label in the tube ( Fig. 8a ) reads: ‘Zulu-land, Umfolozi, 6. 6. 05, Ivar Trägårdh, 2 % subl. 70% alcohol, 16’. The other (re-written) label ( Fig. 8b ) repeats data. The third label ( Fig. 8c ) has: ‘ Microchaetus zulu Michaelsen , 6. 6. 05, Zululand’.

It should be noted that in the tube received from the NHMU, there were three earthworms and two hand-written labels, one of which reads: ‘ Microchaetus colletti sp.n., Zululand, leg. Dahl, det. Beddard, kopi av kartotekkort, Lumbrici, Zululand 1893, Dahl’. The following appears on the other label ( Fig. 9 ): ‘ Microchaetus colletti sp. n., Microchaetus zuluensis sp. n., see P.Z.S. 1907 August’. After the colletti type had been examined, it was sent back to the NHMU, and the species was re-described by Plisko (2000). The two abscised specimens of Microchaetus zuluensis are described in the present paper.The label claiming two species names and the note ‘see P.Z.S. 1907August’ was probably written by Beddard at the time of the original description of both species, as the note refers to Proceedings of the Zoological Society of London, where Beddard described colletti and zuluensis (1907: 277–281).As the specimens of both species and the labels were inserted into the same tube, it is likely that both colletti and zuluensis were collected by Knut Dahl during his excursion to Zululand in 1893–1894.

Other earthworm material included in the re-description of zuluensis by Michaelsen (1913) was collected further south-west of the zuluensis type locality. The site indicated as Mfongosi is located to the south, at the Mfongosi River, a tributary of the Thukela River, and differs from the iMfolozi area as regards soil types, flora and fauna. W.E. Jones was a ‘keen amateur naturalist’ (to quote from Herbert and Kilburn (2004: 53)) who collected numerous litter and soil invertebrates, many of which are located at the NMSA. This non-type material, once included with zululensis , is now found to differ from the type material and should be separately revised.

It is anticipated that new material of zuluensis may provide more data confirming the present species evaluation, and modern research methods might contribute information that sheds further light on relationships between zuluensis and other native South African Tritogenia species.

Figures

Fig. 1. Reproduction of the historical drawing of Microchaetus zuluensis Beddard, 1907 (text-fig. 85), the anterior part of the body, with misleading indication of the simple segmentation.

Figs 2–4. Tritogenia zuluensis (Beddard, 1907): (2, 3) lectotype, anterior part of the body, ventrally (2) and specimen dissected dorsally (3); (4) paralectotype, specimen dissected dorsally.Abbreviations: C – clitellum, Dbv – dorsal blood vessel, G – gizzard, Gp – genital papillae, I – intestine, Tp – tubercula pubertatis. Scale bars = 1 cm.

Figs 5–7. Tritogenia zuluensis (Beddard, 1907), re-examined specimen ‘GNM Oligochaeta 16’ described by Michaelsen (1907) as Microchaetus zulu, accepted as a synonym of zuluensis by Michaelsen (1913): (5) wholespecimen,ventrally; (6) anterior part ofspecimen; (7) anterior part dissected.Abbreviations: G – gizzard, Gg – genital glands, Gp – genital papillae. Scale bars = 1 cm.

Figs 8, 9. Labels: (8) a, b – original by I. Trägårdh, referring to collection locality and preservation method; c – species name, collection area and date (‘Natal Stanford Hill’ refers to another specimen, possibly toM.papillatus); (9) label referring toMicrochaetus colletti andMicrochaetus zululensis, thespecies identified by Beddard, with the added comment: ‘see P.Z.S. 1907 August’.