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Bullina nobilis

Habe, 1950


Patrik Good Bullina sp. or Bullina cf. lineata; Gold Coast Seaway; 9/10/2012; 15:12 hrs; size 10mm; depth 3 metres; 20 degrees water temperature; 2 metres visibility; we are finding lots and lots of Bullinas at the moment, some of them damaged with missing or crushed shell. They range in size from 2mm to 18mm. Whatever we are finding we are calling Bullina lineata or Bullina nobilis. Can I get opinions on wether this individual is an abnormality of one of these two species, lacking the horizontal bands or wether it is a different species all along?

Ajiex Dharma I haven't seen this nice Bulina..

Patrik Good What about Bullina aff. lineata? As far as I know the horizontal shell band is part of the description. So, it can't be B. cf. lineata, can it? What if - hypothetically - the radula were identical to B. lineata though? What if that was a 'once off' genetic mutation, just a colour variation or the critter is actually not fertile and able to produce offspring? Or stated differently: how can I tell the difference between a mere colour variation of a species and a distinctly different species? Do the radula (or mitochondrial DNA) make the decision alone or are they just important factors?

Patrik Good Found a similar but different individual at the same dive site @ 28/8/2012. It had no horizontal shell lines either. The red lines were almost straight.

Gary Cobb Everything externally matches Bullina lineata except the pattern of the red lines. I would call this Bullina cf. lineata. The shell anatomy has to be compared. The thickness of the shell and the shape of the spire are things that need to be compared. Collect an animal and I will preserve the animal to closely compare shells.

Gary Cobb There is no way "we" can compare radula without going through a huge expense. Comparing morphology as best we can and studying descriptions is the best "we" can do. Again if we find an animal we are not sure of BUT resembles another we tag it with cf until a positive ID can be made.

Gary Cobb In these primitive species careful observations of the shell structure are essential to ID. Here are descriptions are the Forum... Bullina nobilis Habe, 1950 Described on the basis of shell differences alone. Differs from Bullina lineata in having a heavier shell, with a low spire, and fewer, more prominent spiral grooves and ridges. The red axial [vertical] lines are thicker than in B. lineata and there are a pair of thick spiral red bands. Each of these thick bands can appear as 2 or 3 individual thinner lines, as in Haruo Kinoshita's accompanying photo. I have copied Habe's original shell description below: 'Shell large for the genus, ovately globose, rather thin, white, with two red bands which divide the body whorl into three subequal parts, and provided with irregularly spaced red longitudinal threads which are somewhat wavy or arcuated or irregular; these threads are interrupted by the bands stated above; spire low; protoconch about 1.5 whorls, smooth and polished; post-embryonal whorls 4, each strongly convex; suture deeply canaliculated; body whorl very large, sculpture with many regular, strongly punctured spiral grooves which are emphatical on the top and base; aperture large, widely lunate; outer lip arcuated and the margin simple and crenated; columellar lip somewhat dilated and slightly twisted on the lower end, covering umbilicus partly and narrowed by the reflection of it. Length: 18 mm, width: 13.2 mm. Distribution: Honshu (Wakayama and the Sagami Bay)' --- Bullina roseana Rudman, 1971 The shell is ovate, globose, umbilicate; pinkish white with two pink spiral lines dividing whorl into 3 parts, the middle one being twice the width of the outer two. A diffuse spiral band runs around the base of the shell. Axial red lines are not well marked except for short lines running down from the suture halfway to the upper pink spiral line. There are approximately 7 axial lines on body whorl. The spire is realtively low, approximately one ninth of shell height, the protoconch is large, whorls rounded. The shell is sculptured with wide smooth spiral ridges, separated by narrow punctate grooves, approximately one third to one quarter the width of ridges. The aperture large, narrowing at the upper end and slightly at the lower end; the outer lip is thin, joining body whorl just above upper red spiral line. Suture channelled. The columella is white, straight, broad, slightly truncated at base, free edge slightly recurved to form umbilical opening. The inner lip forms a calcified layer over the lower half of the shell aperture. This species differs from Bullina lineata in the shape of the shell, animal and radular morphology.

Patrik Good Interesting. Totally agree on the similarity with B. lineata. What bugged me though: all the descriptions mention the horizontal red bands as characteristic. My point was that if one important characteristic of the description doesn't match it can't be that species that was described, can it. Actually, the description might have been too restrictive. If I'd find an elephant with no spout I'd be tempted to not call it 'similar' to an elephant but as something 'similar but certainly not an elephant'. That's why I came up with B. aff. lineata. But maybe the bands are not that important after all and are within a scientifically defined margin of tolerance. As I see shell structure seems to be more crucial (and its description is pretty hard to understand). Thanks a lot, Gary. Will collect the next one I see.

Gary Cobb I often wonder if scientists who describe species 'see' and 'know' of all variations a particular. Species can be!!??

Gary Cobb Patrik check this link out http://www.nudipixel.net/photo/00029263/location/nelson_bay/

Patrik Good That's its brother :-) Ken Thongpila is such an outstanding photographer and naturalist. Did you get this individual IDed by Richard or anybody else, Ken? I also found a Bullina with only one red band on the Seaslug site, Gary (http://www.seaslugforum.net/find/21238). Bill Rudman wrote that he is unsure if it is actually B. lineata but this name should be used until somebody can have a look at its anatomy and radula. That was a few years ago.

Patrik Good Why would it be wrong to call this individual Bullinidae sp. 1? Naming critters is starting to become a very philosphical task, be it by its morphology, radula or mitochondrial DNA. Making distinctions means making a set of decisions. E.g. the elephant with the missing trunk might still have the same teeth structure, the same DNA on some level. In the end the names will be what we decide to name the critters and on what criteria we want to distinguish them from other critters. Who is 'we'? It is all about politics, never about real, pure science. Science is just a good selling proposition. Morphology to a certain extent was in the realm of the layman. It was relatively clear, easy but probably not very exact. Modern science made it more exact I reckon, with more refined methods and data sets. But most of all: the layman can see clear differences to how a species was described and she or he still has to question or speculate if it is a new species or not. Will science fall short of giving us clear, distinguishable criteria in the future, understandable and discernible criteria and not DNA sequences that is? The link of physical appearance and the critters name is the main constant that we hopefully all agree should never be lost or given up totally. A Bullina lineata without being 'lineata' does not make sense even if the radula and the mitochondrial DNA should turn out to be the same. Some part of their DNA has to be different, in order to manifest in these distinct phaenotypes. Isn't that the theory behind it? My point: discernible criteria are needed on what makes a species a species and on how we can weigh several criteria. Well, I probably should start on learning about discernible criteria on a family or clade level :-) Sorry for being boring. Just reflecting for myself really.

Gary Cobb In spite of it all I believe that it is very possible that when Gray described this species he might not have witnessed all the variations. As for me I keep it simple. Bullina cf. lineata is a good start until proven other wise. That's why preserved specimens are so important. Now a days the perfect way to start the process is 2 specimens dropped right into (alcohol) 96% ethanol for DNA analysis. 2 narcotized specimens placed in 30% fresh water/70% mentholated spirits for anatomical and radula work. I have ethanol. These specimens without the intersecting red lines are very interesting! My bet is that they are Bullina lineata.

Gary Cobb ...oh yes and one more thing...you can call it what ever you want. It's your list until proven otherwise!

Ken Thongpila Hi Patrik and Gary, It had been a while already and from I remembered. Around that time I always sent to Dr.Richard before I post to Nudipixel. I saw them so many time in Nelson Bay and everything is the same just different pattern on the shell only... Hope that help :-)

Ken Thongpila BTW thanks for very kind words Patrik :-) You gave me red face now :-)

Deb Aston Is this Bullina lineata? 45mm in size, Gold Coast Seaway, 4m deep, 24 deg water temp

Patrik Good That's big and the water temperature is low too.

Deb Aston This is Bullina nobilis Habe, 1950 (Cephalaspidea: Bullinidae). It's the first record for Australia. This is an exciting find for the Gold Coast Seaway.

Patrik Good Congratulations, Deb. This is sensational. But who - apart from you - could have noticed the difference to Bullina lineata? Well done, expert brancher!

Taxonomy
Animalia (Kingdom)
  Mollusca (Phylum)
    Gastropoda (Class)
      Heterobranchia (Subclass)
         Heterobranchia (Infraclass)
          Acteonoidea (Superfamily)
            Bullinidae (Family)
              Bullina (Genus)
                Bullina nobilis (Species)
Associated Species