Achramorpha nivalis Jenkin 1908
- Dataset
- Description of new chiactine-bearing sponges provides insights into the higher classification of Calcaronea (Porifera: Calcarea)
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Porifera
- class
- Calcarea
- order
- Leucosolenida
- family
- Achramorphidae
- genus
- Achramorpha
- species
- Achramorpha nivalis
description
(Figs 1 A – H; Table 2) Original description. Jenkin 1908, p. 33, pl. XXVII, figs 7 – 8, pl. XXXV and XXXVI, figs 105 – 112.
description
Skeleton. The cortical skeleton is made up by triactines positioned tangentially, diactines and microdiactines (Fig 1 C). Diactines are very long and protruding, unevenly scattered and can cross through the body wall to the atrial cavity (Fig 1 D). Microdiactines are spined and organized around the ostia (Figs 1 C, 1 F). Choanoskeleton inarticulated and mainly composed of the unpaired actines of the atrial chiactines and by the large diactines (Figs 1 B, 1 D). Some cortical triactines can be observed in the middle of the choanosome (Fig 1 D). The chiactines are oriented perpendicularly to the atrium, with the long paired actines adjacent to the atrial wall and the apical actines projecting into the atrial cavity (Fig 1 B). The oscular region is composed of long trichoxeas which form the oscular fringe, and also by thin but large tetractines, which are positioned longitudinally with the unpaired actines pointing towards the base of the sponge (Fig 1 E). Spicules. Diactines: long and straight with both ends sharp. Size: 688.4 ± 328.6 µm length, 14.2 ± 8.2 µm width (Figs 1 C – D; Table 2). Microdiactines: small with hastate points and minute spines towards the hastate tip, which is slender than the other one. Some of these diactines are slightly curved. Size: 80.4 ± 11.5 µm length, 3.4 ± 0.9 µm width (Figs 1 C, 1 F; Table 2). Cortical triactines: sagittal with the unpaired actines straight and longer than the paired actines, which are slightly curved upwards forming a round bend. Paired actines of similar length. Size: unpaired actines 230.9 ± 73.1 µm length, 6.7 ± 2 µm width; paired actines 136.6 ± 43.8 µm length, 6.4 ± 2 µm width (Fig 1 G; Table 2). There are a few triactines with the paired angle almost straight, which probably are from the oscular region. Chiactines: unpaired actines straight and longer than the paired actines. Apical actine straight and tapering to a sharp tip. Size: unpaired actines 462.1 ± 113.1 µm length, 9.4 ± 1.1 µm width; paired actines 175.2 ± 18.9 µm length, 8.8 ± 1.2 µm width; apical actine 102.5 ± 15.9 µm length, 7.7 ± 1 µm width (Figs 1 B – H; Table 2). Oscular tetractines: the unpaired actines are longer and thinner than the paired actines. The apical actine is curved and pointing towards the osculum. Size: unpaired actines 259.7 ± 65.7 µm length, 9.4 ± 0.6 µm width; paired actines 167 ± 6.1 µm length, 12.7 ± 0.5 µm width; apical actines 49.9 ± 5 µm length, 7.7 ± 1.1 µm width (Table 2). Oscular trichoxeas: it was difficult to measure them in the spicule preparations, but according to Jenkin (1908) they are around 2.5 mm length and 6.0 µm width and minutely hastate at the distal end (Fig 1 E). Molecular identification. Not available.
discussion
Remarks. Jenkin (1908) mentioned that there were 14 specimens of A. nivalis in the collection at the BMNH. However, the material available in the museum collection was only one slide from the holotype, one specimen labelled as cotype and several spicules preparations and histological sections, probably from those specimens mentioned by Jenkin (1908). Following the 4 th edition of the International Code of Zoological Nomenclature (ICZN) the term cotype is not recognize by the Code and should not be used in zoological nomenclature, especially e. g. in the sense of syntype or paratype (recommendation 73 E). Therefore, the specimen BMNH- 1907.8.6.111 which was labelled as cotype, is now erected as paratype. All the examined slides from different specimens present the same long projecting diactines in the cortical skeleton, but these are shorter than what was reported in the original description (see Table 2), probably due to the fact that most of them were broken. Jenkin (1908) divided the tetractines in two categories according to the size (see Table 2). This may be associated to the position of the spicules in the oscular area, since it has been observed in other Achramorpha spp. that they are smaller the closer they are to the oscular fringe. However, as most tetractines were broken or not easily visible in the sections, we were only able to measure five complete ones. A third type of diactines was mentioned by Jenkin (1908), who described them as “ rather longer, small, straight hastate oxea ” and of size 120 – 140 µm long, and 4 µm thick. However, we could not find this type of diactines in the material examined, but according to the figure presented by Jenkin (1908) they look similar to microdiactines, but slightly longer (Table 2).
distribution
Distribution and depth. A. nivalis has been reported from two localities around the Antarctic: Winter Quarters Bay (Jenkin 1908), and Winterstation in Wilkes Land in the East-Antarctic, at 350 – 385 m depth (Brønsted 1931).
materials_examined
Type locality. Winter Quarters Bay, Antarctic. Synonyms and citations. Achramorpha nivalis Dendy & Row 1913, p. 765; A. nivalis Hôzawa 1918, p. 542; A. nivalis, Brønsted 1931, p. 32; A. nivalis Burton 1963, p. 93, 526 (fig 332). Material examined. Holotype: BMNH- 1907.8.6.122 (one section slide), Winter Quarters Bay, Antarctic, collection date 11.11.1902. Paratype: BMNH- 1907.8.6.111 (one complete specimen and four slides; see Table 1), Winter Quarters Bay, Antarctic, collection date 29.08.1903. Additional material: BMNH- 1907.8.6.119: one slide, National Antarctic Expedition (HMS Discovery), collection date 08.09.1903. BMNH- 1907.8.6.122 - 124: three slides, National Antarctic Expedition (HMS Discovery). BMNH- 1907.8.6.125: one slide, National Antarctic Expedition (HMS Discovery), collection date 08.09.1903. BMNH- 1907.8.6.128: one slide, National Antarctic Expedition (HMS Discovery), collection date 24.10.1902. BMNH- 1907.8.6.129: one slide, National Antarctic Expedition (HMS Discovery), collection date 24.10.1902. BMNH- 1926.10.26.49: one slide, British Antarctic Expedition 1910 – 1913 (Terra Nova). Morphology. Sponge cylindrical, wider at the base and with well-developed oscular fringe at the narrow end (Fig 1 A). Surface hispid due to long diactines projecting from the choanosome. Colour light brown in ethanol. Aquiferous skeleton syconoid with elongated choanocyte chambers (Fig 1 B). The cotype is 12.95 mm high, 1.87 – 2.94 mm wide and 0.61 – 0.86 mm thick (Fig 1 A).
Name
- Homonyms
- Achramorpha nivalis Jenkin 1908