Leydigia (Neoleydigia) propinqua Sars, 1903

Kotov, Alexey A., 2009, A revision of Leydigia Kurz, 1875 (Anomopoda, Cladocera, Branchiopoda), and subgeneric differentiation within the genus, Zootaxa 2082 (1), pp. 1-84 : 17-29

III. Leydigia (Neoleydigia) propinqua Sars, 1903 emend Sars, 1916

( Figs 23–105 )

Leydigia acanthocercoides (Fisher, 1854) in Sars 1895, p. 18 –22, Pl. 4: figs 1–4.

Leydigia propinqua Sars, 1903, p. 14 , Pl. 1: figs 4, 4a (only South Arfican material); Sars 1916, p. 329 –330, Pl. 38: figs 1, 1a–b; Smirnov 1971, p. 460 –461, fig. 573 (only South African records).

Leydigia africana Gurney, 1904, p. 300 , Pl. 18: figs 5–6.

" Leydigia capensis Sars ", unpublished " types " of G. O. Sars.

? Leydigia propinqua Sars in Johnson 1953, p. 927; Harding 1961, p. 46.

Not " Leydigia mixta Sars ", unpublished " types " of G. O. Sars.

Not Leydigia propinqua Sars in Jenkin 1934, p. 285; Brehm 1937, p. 498; Uéno 1937, p. 101 –102, fig. 85; Uéno 1938, p. 130; Brehm 1951, p. 92; Chiang Sieh-chin and Du Nan-shan 1979, p. 209–210, fig. 140; Chen Shou-zhong 1993, p. 14; Elmoor-Loureiro 1998, p. 35; 2000: Tab. 1.

Type locality. Vicinity of Knysna , Western Cape Province, Republic of South Africa (appr. 34º03'S, 24º05'E) (according to newly selected lectotype) .

Lectotype (selected here). Adult parth. ♀, 760 µm, in 70% alcohol, GOS F12378a.

Paralectotypes (selected here).

(1) Marked as L. propinqua from Knysna: 6 parth. ♀♀, slide GOS F9230 (bad condition); 19 parth. ♀♀, slide GOS F9232; 25 parth. ♀♀, tube NHM 1901.12.12.136–141.; 1 parth. ♀, slide NHM 1901.12.12.136–141.b

(2) Marked as L. propinqua from Cape of Good Hope : 1 parth. ♀, slide GOS F9231; 13 parth. ♀♀, slide GOS F9233 (bad condition); 5 parth. ♀♀, slide GOS F9234 .

(3) Marked as L. acanthocercoides from Knysna: 184 parth. and 5 eph. ♀♀, tube GOS F12378b.

(4) Marked as " L. capensis " from Knysna: 14 parth. ♀, slide GOS F11145 ; 13 ♂♂, slide GOS F11146 ; 13 parth. ♀, slide GOS F11147 .

Notes on typification. Sars (1903) described this species from China and Sumatra from the "northeastern part of Sumatra (territories of Deli and Langkart)". However, he had previously described L. acanthocercoides from Knysna (Cape Colony, now Republic of South Africa) ( Sars 1895), which in fact belongs to the same species. He said that "... the South African form described by me under this name is in reality specifically distinct, for which reason I propose for it the above name" ( Sars 1903, p. 14). According to paragraphs 72.4.1. and 72.4.2. of ICZN (2000), all the specimens from Knysna are members of Sars’ type series. No tube or slide from Sumatra marked by Sars as L. propinqua was found. In contrast, there were numerous tubes and slides with well-preserved specimens, marked as L. propinqua and L. acanthocercoides from Knysna in GOS. In addition, a series of slides and tubes from Knysna was marked as " L. capensis ". No doubt this was a preliminary name of the future L. propinqua , because no other species was described by the author from Knysna in his final publication on South Africa ( Sars 1916). I specially checked the morphology of " L. capensis ", which is a typical L. propinqua . In addition, there is a tube deposited by Sars in NHM as a type of L. propinqua, NHM 1901.12.12.136–141, containing a smaller tube with specimens labelled by him as " L. capensis ", which is final evidence of its identity with L. propinqua . I had the opportunity to select a lectotype from any of these samples. Material in NHM, officially deposited as type by the author, has no priority over other samples: both are syntypes with equal rights to be used for lectotype selection. I preferred to select the lectotype from a tube F12378, marked by Sars " Leydigia acanthocercoides, Knysna ", that contains many well-preserved females. Therefore, Knysna is the type locality of L. propinqua .

A single tube GOS F 12276 with 1 ♀ from Sumatra was marked as " Leydigia mixta ", which is also an unpublished name. I am sure that this was a preliminary name for L. propinqua from Sumatra by Sars (1903); no other taxa were described by him from this island. But this animal is completely different from African L. propinqua , and is Leydigia cf. ciliata in recent understanding (or a similar member of the acanthocercoides - group, but it cannot be determined accurately due to its poor state). The female from Sumatra must be excluded from the type series as belonging to another species.

Other material examined. Republic of South Africa: Kwazulu Natal : Richmond, coll. by J. Gibson, slide NHM 1951.8 .10.683. (appr. 29º53'S, 30º17'E) ; Free State: a water-hole on the veld at Kroonstad, coll. in 1904 by E. Eckersley, tube NHM 2002.690 – 691 . (lectotype of L. africana ) ; Eastern Cape: Pools in Carlisle's Hoek vlei system, coll. 08.02.1998 by K. Martens and Hamer, tube NNS 2002-005 (30º40'34''S, 27º57'28''E) ; Pools 1–2, Carlisle's Hoek Plateau vlei, Rhodes, coll. 01.04.1993 by Martens, deMoor and Barber, tubes NNS 2002-136 – 137 (30º40'44''S, 27º57'28''E) ; Botanical Gardens Dam , Grahamstown, coll. 24.11.1989 by Martens, deMoor and Barber, tube NNS 2002-174 (33º19'00''S, 26º30'50''E) ; Western Cape: Princess vlei, coll. 03.12.1989 by K. Martens, tube NNS 2002-200 (33º52'S, 18º22''E) ; Lesoto: Pool 1 on Thaba Tseka Rd , Drakensberg, coll. 25.11.1993 by K. Martens and M. Seaman, tube NNS 2002-166 (29º25'39''S, 27º51'28''E) .

Diagnosis. Parthenogenetic female. Body subovoid to triangular-ovoid, maximum height in posterior half, dorsal margin almost straight in posterior part, postero-dorsal angle well defined, posterior margin with a 'step' in ventral portion. Valves with distinct coarse striation; fine striation very obscure. In anterior view, body significantly compressed laterally, dorsum like rounded triangle in section. Head small, compound eye small, ocellus always bigger than eye. PP = 2–3 IP, lateral head pores about 1.5 IP distance from midline. Labral keel subtriangular, without setules on its posterior margin, anterior margin with short setules in basal portion, and two lateral groups of short setules on sides of keel. On valves, setae in middle of ventral margin with short setules, and short setules between their bases. In posterior portion of the margin, setae asymmetrically setulated, posteriormost seta long. Setules of submarginal row in ventral portion of posterior margin fine, not organized into groups; in medium third of the margin, more robust, longer, and sparse, marginal membrane with minute 'setules'.

Postabdomen subovoid, robust, preanal margin shorter than anus, in general straight, sometimes with onetwo minute incisions, preanal and postanal angles well defined, distal margin and dorso-distal angle of postabdomen ill-defined. Postanal marginal denticles organised in about 17–18 clusters, about 4 series of marginal denticles on anal margin. About 10–12 fascicles of stout lateral setae, 3–4 setae per each fascicle, marginalmost seta of each fascicle significantly larger then rest, second seta about half its length, next 1–2 setae very fine. About 11–14 fascicles of lateral setules on basal half of postanal and anal margin. Postabdominal claw relatively long, slightly curved in distal half or straight, 2–4 small setules at base, basal spine rudimentary or completely absent.

Antenna I thick, not reaching tip of rostrum, with 4 transverse rows of long setules on anterior face and series of shorter and more robust setules at its end. Sensory seta arising at distance of 1/4 of antenna I length from distal end. Largest aesthetasc somewhat longer than half of antenna I length, reaching tip of rostrum. Antenna II with 2–3 relatively long and stout spine-like setules on first, and 2–3 of these setules on second endopod segment. Apical swimming setae with basal and distal segments bilaterally armed with fine, long setules, no chitinous insertions within distal segments. Basal and distal lateral setae subequal in size, slender, shorter than apical setae.

Trunk limb I ( Figs. 88-89 ) with ODL large, bears series of fine setules and a long seta with unilaterally setulated distal segment. IDL with 3 medial clusters of minute setules, and 3 marginal clusters of larger setules, first IDL seta small, with a few very short setules distally; second and third IDL setae unequal in length, with similar setulation, endite 3 with a relatively long seta 1 and a small receptor near base, endite 2 with two longer soft setae (e–f) subequal in length, seta 2 naked, with a sensillum near base. Two ejector hooks of similar size. Trunk limb II ( Fig. 90 ) with exopodite ovoid, small, with a cluster of long, robust setules, and three series of minute setules. Distalmost scraper with naked basal segment, on distal lobe with distal tuft of short setules and basal group of long setules. Trunk limb III ( Fig. 93 ) with exopodite trapeziumshaped, with seven setae, seta 2 with distal segment setulated bilaterally with short setules, setae 3–4 rudimentary, filter plate with distalmost and basalmost setae smaller than others. Trunk limb IV ( Fig. 94 ) with subovoid exopodite, armed with six setae, setae 2 and, especially 1, short, armed with long, fine setules. Distalmost seta of filter plate with greatly inflated basal segment and denser setulation than rest, located at a distance from the rest, all setae with inflated tips. Trunk limb V ( Fig. 97 ) with semi-circular exopodite, at inner face of limb, two setulated setae of subequal length, but basalmost markedly more slender, with hook near base. Distal armature of gnathobase a lobe with 2 small projections.

Ephippial female. Differs from parthenogenetic female in having dorsal margin almost straight in posterior 2/3 of its length, where dorsal wall of carapace additionally chitinised. In anterior view, body with a thick dorsal keel, more compressed laterally, but chamber for resting egg expands laterally, ephippium slightly pigmented, brownish, without additional sculpture.

Adult male. Body low and ovoid, head large, rostrum long, eye and ocellus of subequal size. Postabdomen elongated, distally gently narrows to an inflated basis of penis and postabdominal claws, distal margin ill-defined. Preanal and postanal angle well-defined, marginal denticles on postanal and anal regions reduced in size as compared with female. Postabdominal claws somewhat shorter than in female. Penis relatively thick, markedly shorter than claw, almost straight. Antenna I more robust than in female, sensory seta and male seta relatively long, subequal in size, both arising at distance of 1/4 of antenna I length from distal end, number aestetascs unknown. Trunk limb I with thin, U-shaped copulatory hook, ODL as in female, IDL with male seta, and two other setae of subequal size, shortest of IDL setae absent. Copulatory brush consisting of relatively short, fine setules, copulatory brush setae short, with inflated basal part.

Size. Parthenogenetic females up to 900 µm, ephippial females 695–730 µm, adult males 445–485 µm.

Full redescription. Parthenogenetic female. General. In lateral view body subovoid to triangularovoid, high, with proportions similar in juveniles and adults (body height/ length = 0.63–0.73 in juveniles and 0.62–0.70 in adults), maximum height in posterior half or in middle ( Figs 23, 29 , 33 ). Dorsal margin uniformly curved anteriorly, and almost straight posteriorly, no depression between head and rest of body. Postero-dorsal angle well-defined; posterior margin with a 'step' in ventral portion, with height varying within a population, margin therefore sinuous in majority of specimens ( Figs 23, 26, 29–30 , 33–36 ). As a result, when valves completely closed dorsally, there is a gap between them ventrally ( Fig. 38 ). Postero-ventral angle completely smooth; ventral margin slightly convex. Valves with inflated coarse striation, with anastomoses dorsally, forming a hexagonal pattern ( Figs 40 , 50–52, 57–58 ). A fine striation not visible under optical microscope, but found under SEM ( Fig. 58 ). Small 'dots on valves' are not external structures (see Kotov 2003). In anterior view, body significantly compressed laterally, with maximum width in region of brood pouch, without dorsal keel, but dorsum like rounded triangle in section ( Fig. 37 ). In ventral and dorsal view body subovoid ( Figs 51–52 ).

Head ( Figs 24 , 53 ) small, 'triangle-round' in lateral view, with short, blunt, downward pointing rostrum. Compound eye small, ocellus of irregular, variable shape, size variable, but always larger than eye, distance from tip of rostrum to ocellus greater than that between ocellus and eye.

Head shield wide, in posterior portion three major head pores with relatively wide connection between them, PP = 2–3 IP ( Figs 39 , 54–55 ). Central pore same size as anterior and posterior, or somewhat narrower, located in middle. Lateral head pores about 1.5 IP distance from midline, at level of central major head pore, without special depressions.

Labrum with fleshy main body, small distal plate, and large medial keel ( Figs 56 , 61–62 ). Distal plate short, boot-shaped, setulated. Main body with lateral projections, setulated dorsally, with series of small setules distally. In lateral view, keel wide, subtriangular, with well-defined apex. Posterior margin almost straight, without setae, anterior margin generally slightly convex to almost straight, slightly undulated, with short setules in basal 1/2–2/3, also two lateral groups of short setules on sides of keel.

Valves large, subovoid to trapezium-shaped, with numerous setae on ventral margin, longest e in anterior and middle portions. The latter with sparser, shorter setulation, their bases located submarginally, short setules between their bases ( Fig. 63 ). In posterior portion of margin, setae setulated asymmetrically, no setules between bases ( Figs 59 , 64–65 ), posteriormost seta long. Posterior to last marginal seta, a submarginal row of short, fine setules starts on valve inner face slightly submarginally, these not organized into groups; in medium third of posterior margin, in region of 'step', setules significantly more robust, longer and sparsely located ( Fig. 60 ), then their size decreases again. Second 'row of minute setules' (Kotov 2003) extends upwards from beginning of 'step' ( Figs 65–66 ). These 'setules' were found 'on' valves of all studied species by optical microscopy, but SEM investigation did not reveal them on either internal ( Fig. 60 ) or external faces of valve. In reality, these are internal structures, located between the external and internal walls of the valve ( Kotov et al. 2003b). I refer to this structure as the 'marginal membrane' ( Fig. 66 , arrow).

Thorax relatively long. Abdomen short, dorsal surface of segments with transverse rows of setules. An inflated distal margin of basal abdominal segment is an analogue of the abdominal projection in Daphnia .

Postabdomen broad, subovoid, robust, with markedly expanding postanal portion ( Figs 27, 30 , 67–68 , 78–79 ). Ventral margin almost straight, with groups of minute setules. Anus located near base, preanal margin shorter than anus, in general straight, with a small projection for postabdominal setae posteriorly, sometimes with one-two minute incisions. Preanal and postanal angles well defined. Whole postanal margin from anus to basis of claws regularly curved, distal margin and dorso-distal angle absent. Each side of postabdomen provided with a row of short postanal marginal denticles ( Figs 67–70 , 80–81 ), organised in about 17–18 clusters, with size slightly increasing distally in each cluster. Clusters of postanal denticles evenly passing into about 4 series of marginal denticles on anal margin. On postanal margin, about 10–12 fascicles of stout lateral setae, decreasing in size basally, 3–4 setae in each fascicle, marginalmost setae of each fascicle significantly larger then rest, second seta about half its length, next 1–2 setae very fine ( Figs 69–70 , 80–81 ). These setae gradually merge with about 11–14 fascicles of lateral setules on basal half of postanal and anal margin, size of setules in each fascicle increasing basally ( Fig. 71 ). Additional row of fine fascicles in preanal region.

Postabdominal seta short, but longer than anal plus preanal margin; distal segment shorter than basal, and armed with long setules ( Fig. 68 ).

Postabdominal claw long, approximately as long as preanal plus anal portion of postabdomen, slightly curved in distal half or straight, with row of small setules along ventral margin ( Figs 72–73 , 82–85 ). Laterally, two successive series of slender setules along dorsal margin, setules of basal series long, distalmost especially long and thickened, also, 2–4 small setules at base of claw. On inner side, setules in basal pecten slightly larger than those in next pecten ( Fig. 74 ). Basal spine rudimentary or absent ( Figs 84–85 ).

Antenna I ( Figs 25 , 75 ) thick, not reaching tip of rostrum, with 4 transverse rows of long setules on anterior face and series of shorter, more robust, setules at its end. Antennular sensory seta long, slender, arising at about 1/4 of way from distal end. Nine aestetascs of slightly different size, largest somewhat longer than half length of appendage and reaching tip of rostrum.

Antenna II ( Fig. 76 ) short. Coxal part with two sensory setae, and lobe with row of fine, relatively long setules. Basal segment robust, with transverse series of numerous, long, fine setules, rudimentary distal spine and short setules at distal margin. Exopod and endopod subequal in length, all segments cylindrical, with fascicles of setules, 2–3 relatively long and stout spine-like setules on first, and 2–3 of these setules on second endopod segment. Antennal formula, setae 0–0–3/1–1–3, spines 1–0–1/0–0–1.

Exopod and endopod with three long apical swimming setae, all with basal and distal segments bilaterally armed with fine, long setules. No chitinous insertions within distal segments ( Fig. 77 ). Basal and distal lateral seta subequal in size, slender, shorter than apical setae. Spine on basal segment of exopod long, reaching middle of apical segment, but never reaching tip. Apical spines of exopod and endopod of similar length, almost twice as long as apical segments.

Maxilla I with 2 relatively large and one small setae, plus a bunch of robust setules. Anteriorly, a paragnath as a setulated hillock ( Fig. 87 , arrow).

Trunk limb I ( Figs 88–89 ) without accessory seta, ODL large, bears series of fine setules and long seta with unilaterally setulated distal segment. IDL with 3 medial clusters of minute setules, and 3 marginal clusters of larger setules ( Figs 86 , 89 ), and three bisegmented setae; first seta small, with few minute setules distally; second and third setae unequal in length, with setules slightly different in thickness.

Endite 3 with three soft setae (a–c), size increasing basally, a stiff seta (1) anterior to them, a small receptor near its base. On endite 2 three densely setose setae (d–f), two long (e–f) subequal, third (d) shorter, and a small, naked seta (2) with a sensillum near its base on inner face of limb. Endite 1 with three 2- segmented setae (g–i), and a small seta 3. Fascicles of slender setules on inner face of limb, plus clusters of longer, more robust setules at ventral margin. Two ejector hooks of similar size. On limb base, a simple maxillar process with single row of setules.

Trunk limb II ( Figs 90–92 ) with small, globular epipodite. Exopodite ovoid, relatively small, without setae, but with a cluster of long, robust, and three series of minute, setules. Inner portion ('endopodite') with eight scrapers ( Fig. 90 : 1–8). Distalmost scraper (1) with long setules distally, naked basal segment, on distal lobe with distal group of minute setules and basal tuft of long setules ( Fig. 91 ). A series of small projections posterior to distal scrapers. Portion of gnathobase bordering 'endopodite' somewhat inflated, and densely setose. Distal armature of gnathobase with four elements ( Fig. 92 : 1–4), one of them a small sensillum. Filter plate with seven setae of subequal size.

Trunk limb III with sub-globular epipodite. Exopodite trapezium-shaped, with three large lateral setae ( Figs 28 and 93 : 5–7), basalmost (7) longest, two rudimentary setae (3–4), and two distal setae (1–2) of unequal size and armature, seta 2 with distal segment setulated bilaterally with short setules ( Fig. 94 ). Distal endite with three setae ( Fig. 95 : 1–3), distalmost (1) and middle (2) ones stout, their distal segments with minute setules, basalmost seta (3) asymmetrically armed distally. A small sensillum near each seta 2 and 3. Basal endite with four setae (4–7), armed with fine, short setules distally, bottle-shaped sensillum near seta 4. On posterior limb face, four soft setae ( Fig. 93 : a–d), distalmost seta (a) longest, all armed with long, fine setules distally.

Distal armature of gnathobase with very thick, bottle-shaped sensillum ( Fig. 95 : 1), long, slender seta, with long setules distally (2), and two smaller setae (3–4), with a group of long setules nearby. Filter plate with six bilaterally setulated setae, distalmost and basalmost setae smaller than others.

Trunk limb IV with setose pre-epipodite and globular epipodite. Exopodite wide, subovoid, with six setae ( Fig. 96 : 1–6). Setae 3 longest, 4, 5 and 6 successively shorter, all with long, fine setules, extended in same plate; setae 1 shortest, seta 2 also short, both with long, fine setules.

Inner portion with four marginal setae ( Fig. 96 : 1–4). Distalmost seta (1) stout, with minute setules distally, setae 2–4 with inflated basal segments and slender, unilaterally setulated distal segments, in seta 2 basal segment also setulated. Slender sensillum near seta 2. On posterior face of limb, three soft setae (a, c–d) and a straight, tri-lobed sensillum (b). Distal armature of gnathobase with a thick, bottle-shaped sensillum ( Fig. 96 : 1), a long 2-segmented seta, with distal and basal segments unilaterally setulated (2), a small hook distally (3), and a short receptor on anterior limb face (4). Filter plate with five setae, distalmost with greatly inflated basal segment and denser setulation than rest, located some distance from rest, all setae with inflated tips.

Trunk limb V with small setose pre-epipodite, and large epipodite, exopodite very large, semi-circular, with four setae whose long setules lie in the same plane ( Fig. 97 : 1–4), distally only a row of long marginal setules. Inner portion of limb an elongate, flat lobe, with setulated inner margin and group of particularly robust setules distally. On inner face, two setulated setae of subequal length, but basalmost markedly more slender, with a hook near its base. Distal armature of gnathobase a lobe with 2 small projections and two setae in 'filter plate'.

Ephippial female. In lateral view, shape basically as parthenogenetic female, of slightly greater height (body height/ length = 0.66–0.73), but dorsal margin almost straight in posterior 2/3 of its length, where dorsal wall of carapace additionally chitinised, forming very thin dorsal plate ( Figs 41–43 ). In anterior view, body with a thick dorsal keel, more compressed laterally than parthenogenetic female, but chamber for resting egg expands laterally. Ephippium transparent, no additional pigment, with single resting egg, no additional sculpture. 'Dots' visible under optical microscope on surface of valves are not external structures, and coarser than in parthenogenetic female. No distinct border between ephippium and rest of valves.

Adult male. Only slides were available, so level of study constrained.

General. Body low and ovoid, body height/ length = 0.59–0.63 ( Figs 31 , 44 ). Head larger and rostrum longer than in female ( Fig. 45 ). Eye and ocellus of subequal size. Anterior margin of labrum without undulation. Valve with posterior margin ( Figs 32 , 46 ) as in female.

Postabdomen elongate, with straight ventral margin and regularly convex dorsal margin, maximal height on level of postanal angle, gradually narrows distally to inflated basis of penis and postabdominal claws, distal margin not defined ( Figs 32 , 47 ). Preanal margin straight, with low incisions, as long as anal margin, preanal angle well-defined, postanal angle well-defined. Marginal denticles in clusters on postanal and anal regions smaller than in female ( Fig. 48 ). A single lateral cluster of very slender, straight setules near basis of claws, then 7–8 lateral fascicles of setae, 2–4 setae in each, in middle and basal portion, 4–5 in distal portion, about 10–12 lateral fascicles of setules in basal portion of postanal and anal regions. Postabdominal claws somewhat shorter than in female. Penis ( Fig. 49 ) relatively thick, markedly shorter than claw, almost straight, with pair of gonopores atn tip, each opening on short, somewhat narrowing projection.

Antenna I ( Fig. 45 ), more robust than in female, sensory seta and male seta relatively long, subequal in size, both arising 1/4 of way along length from distal end, number aestetascs unknown. Antenna II as in female.

Trunk limb I with slender, U-shaped copulatory hook, with distal ridges. ODL as in female. IDL with male seta, and two setae of subequal size, shortest IDL setae absent. Portion of limb near hook inflated and supplied with copulatory brush of rather short, fine setules. A copulatory brush setae short, with inflated basal part.

Size. Lectotype 760 µm, juvenile and adult parthenogenetic females from Knysna 390–860 µm (n = 50), ephippial female 695–730 µm (n = 5), adult male 445–485 µm (n = 10). According to Sars (1916), length "scarcely exceeding 0.9 mm".

Differential diagnosis. The only differences within the subgenus are discussed here and below. L. propinqua is the most primitive member of the subgenus, having a series of unique and rare traits. Only in this species are (1) small-scale striation on valves rudimentary, almost invisible under optical microscope; (2) no groups of setules on posterior labral margin; (3) preanal margin of postabdomen completely smooth. Also, in only two species, L. propinqua and L. australis , is setulation on anterior margin of labral keel short; only in 2 species, L. propinqua and L. macrodonta , are lateral head pores located far from major pores; only 2 species, L. propinqua and L. microps , have seven setae on exopodite III.

Taxonomical comments. Descriptions of the South African ' L. acanthocercoides ' by Sars (1895) was relatively detailed and accompanied by realistic pictures. He specially pointed out and illustrated the "slightly bulging in the middle" posterior margin. As shown above, Sars (1903) mixed two different species in his description of new species. Understanding of this species must be based on his later publication ( Sars 1916), and this is now confirmed by the lectotype selection.

Apparently, some subsequent determinations were due to unclear ideas on this species during the 20th century. Even records of L. propinqua from South Africa ( Johnson 1953; Harding 1961) and tropical Africa ( Brehm 1959) may deal either with this or other species. Due to problems of understanding Sars' species, Jenkin (1934) apparently described another taxon under this name, then Gauthier (1939) named the latter as L. propinqua var. ciliata (see below). Asian and South American findings of L. propinqua ( Brehm 1937; Uéno 1938; Chiang Sieh-chin and Du Nan-shan 1979; Chen Shou-zhong 1993) are very dubious: I am sure they were misidentifications.

Distribution. According to my samples, L. propinqua occurs only in the southern corner of Africa, extending north only to 27ºS, but in this region it is the most common species of Leydigia .

Figures

FIGURES 23–32. 23–28. Leydigia propinqua, lectotype, parthenogenetic female from vicinity of Knysna, Western Cape Province, Republic of South Africa. 23–25. General view, head and antenna I. 26–28. Posterior margin, postabdomen and exopodite III. 29–32 Leydigia propinqua, paralectotypes selected from samples provisionally marked by G. O. Sars as 'Leydigia capensis Sars' from Knysna. 29–30. Parthenogenetic female from slide GOS F11145 and its postabdomen. 31–32. Adult male from slide GOS F11146 and its postabdomen. Scale bar denotes 100 µm for 23–24, 26–32; 10 µm for 25.

FIGURES 33–49. Leydigia propinqua, paralectotypes from vicinity of Knysna, Republic of South Africa from tube GOS F12378b (33–43) and slide GOS F11146. 33–36. Parthenogenetic female in lateral view and variability of shape of its posterior margin. 37–38. Anterior and posterior view. 39. Head pores. 40. A fragment of valve surface. 41–43. Ephippial female in lateral and anterior view and a fragment of its valve. 44–46. Adult male, its head and posterior margin of valves. 47–49. Male postabdomen, its middle and distal portion. Scale bar denotes 100 µm.

FIGURES 50–60. Leydigia propinqua, parthenogenetic female, paralectotype from Knysna used for SEM. 50–52. Lateral, dorsal and latero-ventral view. 53–55. Head and dorsal head pores. 56. Labral keel. 57–58. Valve sculpture. 59–60. Armature of ventral margin of valve in external view, and posterior margin in internal view. Scale bar denotes 100 µm for 50–53, 10 µm for 54–60.

FIGURES 61–77. Leydigia propinqua, parts of dissected paralectotype, parthenogenetic female from vicinity of Knysna. 61–62. Labrum. 63–64. Setae at middle and postero-ventral region of valves. 65–66. Armature of posterior margin of valve in inner view. 67–70. Postabdomen anf middle of its postanal margin. 71. Series of lateral setae in middle of postanal margin. 72–73. Distal portion of postabdomen. 74. Postabdominal claw in inner view. 75. Antenna I. 76–77. Antenna II and its apical swimming seta. Scale bar denotes 100 µm.

FIGURES 78–86. Leydigia propinqua, parthenogenetic female, paralectotype from Knysna used for SEM. 78–81. Postabdomen and its postanal portion. 82–83. Postabdominal claws in lateral and latero-distal view. 84–85. Bases of postabdominal claws in lateral and dorso-lateral view. 86. Distal portion of limb I. Scale bar denotes 100 µm for 78–79, 10 µm for 80–86.

FIGURES 87–97. Leydigia propinqua, maxilla I and thoracic limbs of dissected paralectotype, parthenogenetic female from vicinity of Knysna. 87. Maxilla I and paragnath. 88–89. Limb I and its distal portion. 90–92. Limb II, its distal portion and distal armature of gnathobase. 93–95, Limb III, distal portion of its exopodite, and its inner portion. 96. Limb IV. 97–98. Limb V and its gnathobase. Scale bar denotes 100 µm.

FIGURES 99–106. 99–102. Leydigia africana Gurney, 1904, lectotype, parthenogenetic female NHM 2002.690., which is obviously L. propinqua Sars, 1903. 103–106 'Paralectotype' of Leydigia africana Gurney, 1904, parthenogenetic female NHM 2002.691., which obviously belongs to a species different from the lectotype, namely, L. ciliata Gauthier, 1939 in its recent understanding. Scale bar denotes 100 µm.