Dadagulella browni browni (van Bruggen, 1969 ) browni (van Bruggen, 1969

Rowson, Ben & Tattersfield, Peter, 2013, Revision of Dadagulella gen. nov., the “ Gulella radius group ” (Gastropoda: Streptaxidae) of the eastern Afrotropics, including six new species and three new subspecies, European Journal of Taxonomy 37, pp. 1-46 : 11-13

Dadagulella browni browni (van Bruggen, 1969) comb. nov.

Figs 23-26 , 47-48 , 71, 74 , 82 , 84 ; Table 1

Gulella browni van Bruggen, 1969: 69-71 , figs 25-26.

Gulella browni – van Bruggen & Appleton 1977: 31-32. — Aiken 1981: 321-323, fig. 5. — Richardson 1988: 60. — Verdcourt 1990: 349. — van Bruggen & Van Goethem 1999: 40. — van Bruggen 2000: 233-234. — Herbert & Kilburn 2004: 212. — Rowson & Lange 2007: 31. — Muratov 2010: 277.

“a closely related species from Zululand” – Verdcourt 1985: 119.

Gulella cf. radius – Tattersfield et al. 2006: 52, 54, 58.

Type material examined

SOUTH AFRICA: holotype RMNH.MOL.54894 : 1 ad., Lake Sibayi (approx. 27.34°S, 32.71°E), KwaZulu-Natal, dune forest on the east shore, leg. D.S. Brown, 12 Jun. 1966 (examined digital photograph only).

Other material examined

TANZANIA: NMW.Z.2003.001.00008: 6 ads, 5 juvs, Mt. Mwanihana Forest Reserve (7.82°S, 36.83°E), Udzungwa Mts National Park, Kilombero District, lowland forest at approx. 600-900 m alt., leg. BR, PT, MBS & CFN, 29 Jan. 2003. NMW.Z.2003.001.00009: 4 ads, data as previous but 700 m alt. NMW.Z.1997.007.00003: 5 ads, 2 juvs, Mzelezi Forest Reserve (8.79°S, 36.72°E), Mahenge Mts, Ulanga District, forest on limestone, approx. 645 m alt., leg. PT, MBS & CFN, 6 Feb. 1997. NMW.Z.1997.007.00004: 1 ad., data as previous. NMW.Z.1997.007.00005: 2 ads, 6 juvs, data as previous.

MOZAMBIQUE: NMW.Z.2012.040.00001: 2 ads, Pomene Bay, Inhambane Province, near lighthouse S of old hotel (22.9417°S, 35.5913°E), degraded dune forest, in leaf-litter, leg. D. Herbert, Oct. 2002 (ex NMSA.L5797). NMSA.L5797: 2 ads, data as previous.

SOUTH AFRICA: NMW.Z. 2012.040.00002: 3 ads, Kosi Bay mouth, KwaZulu-Natal (26.89°S, 32.88°E), dune forest, in sandy leaf-litter, leg. D. Herbert & L. Davis, “11-41”, 13 Oct. 2011 (ex NMSA. W8517). NHMUK.20110173: 2 ads, Lake Sibaya area of Tongaland (approx. 27.35°S, 32.67°E), Zululand, S. Africa, leg. C.C. Appleton, Dec. 1972 - Nov. 1973.

Description

SHELL ( Figs 23-26 , 47-48 ). Small (2.60 - 3.20 mm high x 1.60 - 1.90 mm wide), of 5.5 - 6.0 whorls. Ovateacuminate, spire broadly acuminate (spire angle 66 - 76°). Apex pointed. Embryonic whorls smoothly granulate. Later whorls with relatively coarse ribs (11 - 15 per mm on penultimate whorl). Sutures relatively shallow. Umbilicus closed or narrowly open. Peristome incomplete parietally. Outer palatal surface of aperture with a depression corresponding to the palatal tooth and another much weaker one corresponding to the basal tooth. Dentition 7-fold to 8-fold, consisting of: one lamella-like parietal tooth and (almost always) one additional parietal denticle; one slab-like palatal tooth, forming a narrow parieto-palatal sinus; two basal denticles; a deep-set columellar baffle, sometimes folded, and one or two shallower columellar denticles. Dentition of 8-fold individuals alternatively recognisable as 7-fold, depending on the interpretation of the columellar and parietal denticles (van Bruggen 1969). Juvenile shells of D. browni comb. nov. were not known to van Bruggen (1969, 2000). Herbert & Kilburn (2004) describe them simply as dentate, but with dentition different from that of the adult. Juveniles from southern Tanzania ( Figs 47-48 ) have dentition similar to, but weaker than, juveniles of D. r. radius comb. nov. ( Figs 43-45 ).

CEPHALOPODIUM. Pale cream, with pink-orange tentacle retractors and a few purple-brown speckles in the mantle.

SALIVARY GLANDS ( Fig. 71 ). United, soft, not tumid, elongate, bilobed; each duct leaving at the whitened apex of the lobe and evenly thick throughout.

RADULA. Described and figured by Aiken (1981) as having a unicuspid, ‘heart-shaped’ central tooth and nine laterals in each half-row, of which at least the inner six are tricuspid, diminishing gradually in size laterally. The outer cusps of most teeth are smaller than the inner cusp. According to Aiken (1981) the teeth are flexible when pressed by a cover slip and there are 47 rows.

GENITALIA ( Figs 74 , 82 ). Upper parts of spermoviduct not recovered. Vas deferens appearing thickened prior to insertion on penis but actually with a very short, broad parallel diverticulum. Penial sheath absent. Interior of penis with weak radial pilasters. Apical, muscular part of penis with a single large hook, associated with a spatulate “scoop” with microscopically serrated tip. Elsewhere in penis, a single longitudinal row of short, simple hooks.

Range and habitat

Coast of north-eastern South Africa: dune forest, coastal forest and bush; also central Mozambique: high forest in Chiluvo [Xiluvo] hills (19.24°S, 34.06°E) at 700 ft (approx. 213 m) elevation (van Bruggen 1969; van Bruggen & Appleton 1977; Herbert & Kilburn 2004). Also in lowland forest, up to 900 m, in southern Tanzania, as far north as 7.8°S.

Remarks

We agree with van Bruggen (1969) that the complex dentition of D. browni comb. nov. s.l. separates it from D. radius comb. nov. s.l., which never seems to have 8-fold dentition, in particular the extra parietal and basal denticles. The shells of D. browni comb. nov. s.l. are also much smaller, less elongate (i.e. have a lower height/width ratio), and have a much narrower and more horizontal parieto-palatal sinus than is usual for D. radius comb. nov. s.l. Although some specimens of D. r. radius comb. nov. approach D. browni comb. nov. s.l. in one or more of these respects (e.g. Figs 10, 14, 17 ) all can be readily assigned to one or the other and the type specimens are morphologically quite different ( Figs 1-5 , 11 , 52 vs. Fig. 26 ). Material intermediate between D. browni comb. nov. and D. radius comb. nov. might be expected in the intervening area of southern Tanzania or northern Mozambique. However, all the relevant southern Tanzanian material here (e.g. from Mafia and Mahenge) is closer to D. browni comb. nov. s.l. in dentition and other aspects. A recent survey in northern Mozambique ( Muratov 2010) encountered only D. delgada comb. nov.

Figures

Figs 6-26.Adult shells of Dadagulella radius (Preston, 1910) comb. nov., D. browni (van Bruggen, 1969) comb. nov. and their respective subspecies. 6-20. D. radius comb. nov. s.l. 6-8. D. radius calva (Connolly, 1922): 6. Lectotype, Taru Desert. 7. Taru Desert near Malindi. 8. Near Mombasa. 9-20. D. radius radius: 11. Lectotype, Shimba Hills. 12. Gazi. 13. also Gazi. 14. Diani Beach. 15. Amboni. 16. Kimboza. 17. Mkungwe. 18. Pugu. 19. Mbudya I. 20. Jozani. 21-26. D. browni comb. nov. s.l.: 21. D. browni mafiensis subsp. nov., holotype, Mlula. 22. D. browni semulikiensis subsp. nov., holotype, Semuliki NP. 23-26. D. browni browni: 23. Mwanihana. 24. Mzelezi. 25. Pomene Bay. 26. Holotype, Lake Sibayi (after van Bruggen 1969).

Figs 43-50. Juvenile shells of Dadagulella gen. nov. species, with dentition emphasized in basal view including earlier dentition visible through the shell. 43-45. D. radius radius, Mbudya I. 46. D. pembensis sp. nov., Ngezi. 47-48. D. browni browni, Mwanihana. 49.? D. ecclesiola sp. nov., Kimboza. 50. D. minareta sp. nov., Kimboza.

Figs 69-76. Salivary glands and genitalia of Dadagulella gen. nov. species. 69. D. radius radius, Amboni. 70. D. pembensis sp. nov., Ngezi. 71. D. browni browni, Kosi Bay. 72. D. delta sp. nov., Mwanihana. 73. D. radius radius, Amboni. 74. D. browni browni, Kosi Bay. 75. D. pembensis sp. nov., Ngezi. 76. D. delta sp. nov., Mwanihana. Abbreviations: ad = anterior duct of salivary gland; ag = albumen gland; at = atrium; bc = bursa copulatrix; bd = bursa duct; dv = diverticulum of vas deferens; e = egg; fo = free oviduct; hdd/t = hermaphroditic duct diverticulum / talon; ma = muscular apex; p = penis; pd = posterior duct of salivary gland; pr = penial retractor muscle; v = vagina; vd = vas deferens.

Figs 77-83. Penes and spermatophores of Dadagulella gen. nov. species. 77. D. radius radius, Amboni, penis with spermatophore in situ. 78. Same, hook and scoop in situ when hook lifted back to expose scoop. 79. D. pembensis sp. nov., Ngezi, penis. 80, same, spermatophore from penis of another individual. 81. D. delta, Mwanihana, penis. 82. D. browni browni, Kosi Bay, penis (diagrammatic). 83. D. radius crassa, Amboni, scoop magnified to show serrated edge. Abbreviations: cl = chitinized lobe; lh = large apical hook; ma = muscular apex; pr = penial retractor muscle; sc = apical scoop; st = spermatophore tail; sr = spermatophore reservoir; vd = vas deferens.

Fig. 84. Distribution of Dadagulella gen. nov. species, based on published records and material examined here (for additional records of D. meredithae comb. nov. in northern Malawi see van Bruggen 2000). The inset on the left corresponds to the map on the right.

Figs 1-5. Lectotype of Ennea radius Preston, 1910, type species of Dadagulella gen. nov. 1. Apical view. 2. Apertural view. 3. Last two whorls, from left side. 4. Last two whorls, from right side. 5. Umbilical view.

Figs 51-64. Apertures of adult shells of Dadagulella gen. nov. species (not to scale). 51. D. radius calva, lectotype, Taru Desert. 52. D. radius radius, lectotype, Shimba Hills. 53. D. radius radius, Amboni. 54. D. browni mafiensis subsp. nov., holotype, Mlula. 55. D. browni semulikiensis subsp. nov., holotype, Semuliki NP. 56. D. ecclesiola sp. nov., holotype, Kimboza (two views of shell showing basal tooth only visible when shell angled). 57. D. cresswelli sp. nov., holotype, Ngorongoro. 58. D. minareta sp. nov., holotype, Kimboza. 59. D. cuspidata comb. nov., holotype, Shume (note shell angled slightly differently to that in Fig. 31). 60. D. pembensis sp. nov., holotype, Ngezi. 61. D. frontierarum sp. nov., holotype, Mtai. 62. D. minuscula minuscula, lectotype, Nzwani. 63. D. minuscula minuscula, paralectotype, Nzwani. 64. D. minuscula mahorana subsp. nov., holotype, Mayotte.