Caridina africana Kingsley, 1882

Richard, Jasmine & Clark, Paul F., 2010, Caridina H. Milne Edwards, 1837 (Crustacea: Decapoda: Caridea: Atyoidea: Atyidae) - freshwater shrimps from eastern and southern Africa *, Zootaxa 2372 (1), pp. 305-337 : 306-309

Caridina africana Kingsley, 1882

( Figs. 1–2 )

Caridina africana Kingsley 1882: 127 , pl. 1, figs. 3, 3a. — Sharp 1893: 111. — Ortmann 1894: 402, 404. — Bouvier 1905: 74. — Hart et al. 2001: 111, fig. 6.4A. — Lenz 1912: 5. — Richard & Clark 2009: 5–14 , figs. 1–3.

Caridina wyckii var. paucipara Weber 1897: 168 . — Bouvier 1905: 73 (key), 79–80.

Caridina nilotica var. paucipara . — De Man 1908: 263, pl. XX, fig. 4, 4a, 4b. — Lenz 1912: 5.

Caridina typus. — Weber 1897: 167 (partim).

Material examined. Types: Caridina africana : female syntype, South Africa stn 412, Natal , Zululand, coll. S. A. Grant, USNM 84331 , coll. acc. no. 2876. Caridina wyckii var paucipara : lectotype ov. female, paralectotypes 1 male, 2 ov. females, 2 females (lectotype and paralectotypes selected by Y. Cai with note in jar, and accepted by the present study) River Umhlasine, Natal 1894, pres. & det. M. Weber, ZMA Crust De 102887 .

Non-types: South Africa, small streams near Grey Town, Kwazulu, Natal , June 1909, NHM 1909.VII.27.1–10, 7 females, 1 juv. ; Umbilio River pools, Pine Town, Natal , 10 miles from Sea , SAM A3133 , 5 males , 2 ov. females, 2 females, 1 juv.; Umbilio River, ZMA Crust De 240995, 1 ov. female; Eshore Empangeni area , SAM A8442 , 7 males , 6 ov. females, 11 females; Otobotini, Zululand, Natal Museum , SAM A8444 , 2 males , 1 ov. female, 2 females; Inyalazi River , July 1915, SAM A3754 , 2 males , 3 ov. females, 8 females, 7 juv.; Cabris Road stream, Hay fields, Pietermatrizburg , 29° 36'S 030° 24'E, coll. Rob Hart, University Kwazulu, Natal, NHM 2009.235–244, 1 female (selected from a lot of rostrum or telson damaged specimens) ; swamp forest of Zululand, 28°45'S 31°50'17"E, University of Zululand, AM REA 1332 A, 4 ov. females; Mooi River , Potchelptroom, Natal , AM GEM 1423 A, 1 male , 9 ov. females; no locality given, SAM A3142 9 females ; ZU 73J, 1 ov. female. Mozambique, Tete on Lake Zambezi , 18°50'35"S 36°17'27"E, AM CAW 264 , 1 male , 2 ov. females, 2 females.

Description. Total length: 25–35 mm. Carapace length: 5–5.75 mm.

Rostrum ( Figs. 1a–c ): straight, extending to peduncle, equal to antennal scale or longer, 4.0– 4.9 mm in length, 0.8–0.9 as long as carapace.10–22 teeth present on dorsal margin leaving 0.35–0.65 of length distally unarmed. 1–4 post-orbital teeth. 9–20 teeth on ventral margin extending from proximal end to tip or leaving a short distance unarmed distally. Tip normally bifid or acute. Formula (1–4) 10–22/9–20.

Antennular peduncle: 0.6–0.7 as long as carapace. Stylocerite 0.6–0.8 of length of basal segment. Anterolateral teeth of basal segment 0.2–0.25 as long as second segment. 8–20 segments bearing aesthetascs.

First pereiopod ( Fig. 2a ): dactylus 1.0–1.2 as long as palm of propodus. Chela 2.0–2.5 as long as wide. Carpus 1.7–2.5 as long as wide, with moderate excavation anteriorly.

Second pereiopod ( Fig. 2b ): dactylus 1.1–1.3 as long as palm of propodus. Chela 2.5–2.7 as long as wide. Carpus 4.1–4.3 as long as wide.

Third pereiopod ( Figs. 2c–d ): dactylus 2.4–3 as long as wide. Spines on dactylus varying from 8–11 (including terminal spines). Propodus 4.5–5 as long as dactylus and 11–13 as long as wide with 9–14 spines along inner margin. Carpus 0.65–0.7 as long as propodus, with 1 large spine and 4 or 5 small spines on inner margin. Merus 1.5–1.7 of carpus length. Merus with 3 large spines along posterior margin. Ischium with one spine.

Fifth pereiopod ( Figs. 2e–f ): dactylus 3.75–4.2 as long as wide with 45–55 spines in comb-like arrangement on inner margin. Propodus 15–17 as long as wide and 2.75–5 as long as dactylus with 10–15 spines along posterior margin. Carpus 0.5–0.6 of propodus length and with one large spine and 4–6 minute spines along inner margin. Merus 1.4–1.7 of carpus length, with 2 large spines along posterior margin.

Setobranch: mostly 4 setae but this varied between localities with counts of 2–4.

First male pleopod ( Figs. 2g –h ): endopod 0.45–0.55 of exopod length. Appendix interna present or absent.

First female pleopod: endopod 0.5–0.65 as long as exopod.

Eggs ( Fig. 2i ): 45–65, 0.9–1.1 × 0.65–0.75 mm in size.

Second male pleopod ( Fig. 2j ): appendix masculina 1.6–2.1 as long as appendix interna, 0.4 as long as endopod.

Sixth abdominal somite: 0.5–0.6 as long as carapace.

Telson ( Figs. 2k–l ): 1.0–1.1 as long as 6 th abdominal somite. 5–10 pairs of dorsal spines (including subterminal spines). Posterior margin triangular mostly converging to median pointed process (rarely without process) with 1 pair of lateral spines, 2 or 3 pairs of inner spines. All spines sparsely plumose, slightly shorter than lateral spines.

Uropod ( Fig. 2m ): 11–17 diaeresis spinules.

Preanal carina ( Fig. 2n ): unarmed.

Distribution. Natal, South Africa; Mozambique.

Remarks. Richard & Clark (2009) examined and described the only extant type specimen, a female, of C. africana . They attempted to provide additional key characters by selecting similar specimens from Umbilio River pools, Pine Town, Natal, to confirm the limited distribution of the species and to distinguish C. africana from C. togoensis Hilgendorf, 1893 which is widely distributed in Africa. For the present study more specimens from around the type locality of Natal were examined including cotypes of Caridina wyckii var. paucipara . The type material comprises one male, two ovigerous female and two females. These specimens from the River Umhlasine, Natal agree well with C. africana in having a rostrum that is shorter or slightly longer than the antennal scale, fewer teeth (13–19) on the dorsal margin of the rostrum, 0.45–0.65 of dorsal margin of the rostrum unarmed, the unarmed dorsal distal margin not interrupted by teeth, the dactylus of the third and fourth periopod being 4.9–5.3 times the propodus, 13–17 uropod diaeresis spinules and the posterior margin of the telson triangular converging to a pointed midpoint bearing 1 pair of lateral spines and 2 pairs of inner spines. This present study confirms that C. africana of Kingsley (1882) and C. nilotica var. paucipara of Weber (1897), both from Natal, are conspecific.

The significance and importance of the male appendix interna as a diagnostic character is again challenged. Gordon (1933: 354–355, text figs. 2–3) was the first to recognise that the male appendix interna varied. She was unable to provide an explanation and considered that this variation in C. nilotica may be a sexual process that was present for a short time during the breeding season, but noted that no exact data on this point were available. Coutière (1901), observed the correlation between male dimorphism and the sexual activities of palaemonid prawns. However, for Macrobrachium rosenbergii (De Man) , Barki et al. (1991a, b) recognised three types of males in their experimental communal cultures: dominant, subdominant and submissive. The relative size of the 2nd pereiopod to body size was quite different, but there was no relationship between the presence of an appendix interna and the social hierarchy in males. Such detailed studies on the presence and absence of an appendix interna on the endopod of the first pleopod in males of a population probably might bring out the occurrence of male morphotypes in several species of Caridina . Later, Chace (1997: 15–16, fig. 8a–k), referring to C. longirostris , commented that the appendix interna displays various degrees of development, irrespective of specimen size, and it therefore seems to be an unreliable character in his species. Richard & Clark (2005: 717, fig. 4) too referred to this male character while studying C. nilotica . They remarked that the shape of the endopod as well as the presence or absence of an appendix interna varied and illustrated twenty examples. From their observations, the absence of the appendix interna on the endopod seems to be a regular feature in specimens from the southern regions of the Nile Basin from Tanganyika north to White Nile at Malakal, Sudan. However, in the northern basin, specimens with and without appendix interna were recorded. Richard & Clark (2005) concluded that identifying yet another species based on the presence or absence of appendix interna seemed unwarranted since the other characters fell within the variation expected for C. nilotica . Furthermore, Holthuis (1965: 9) based his key of Madagascan Caridina by distinguishing two distinct groups; those species in which the male appendix interna is present and those without this character. With respect to the appendix interna for C. africana , it was present in the males of ZMA Crust De 102887 and SAM A3133; absent in SAM A8444 and AM CAW 264; but both present and absent in males from SAM A8442. Consequently the appendix interna is still not considered to be a consistent reliable character.

Figures

FIGURE 1. Caridina africana Kingsley, 1882, ZMA De 102887, 2 ov. females. a, anterior region of cephalothorax; b, anterior region of cephalothorax, NHM 2009.235–244, female; c, anterior region of cephalothorax.

FIGURE 2. Caridina africana Kingsley, 1882, ZMA De 102887; a, first pereiopod; b, second pereiopod; c, third pereiopod; d, dactylus of the third pereiopod; e, fifth pereiopod; f, dactylus of fifth pereiopod; g, first pleopod (male); h, endopod of first male pleopod; i, egg; j, appendix masculina; k, telson; l, posterior margin of telson; m, uropod diaeresis spinules; n, preanal carina. a–f, I, k–n ov. female; g–h, j male.