Presented by Dr Hans Ho

Associate Researcher, National Museum of Marine Biology & Aquarium, Taiwan; Associate Professor, Institute of Marine Biology, National Dong Hwa University, Taiwan; and, Research Associate and Visiting Scientist, Australian Museum.

Recorded Wednesday 15 March 2023

Good afternoon, everyone. This is my talk about Barracudina, the family Paralepididae. So interestingly that this fish, I mean, it's quite common in our environment but it's quite rare to most people and I think it's because that this (fish) can move quite fast. And then because they are quite slender, it's not easy to collect them by trawl, so that's why not many people have that. However, not many collections have this fish. However, the juvenile is quite common, maybe because they don't have the ability to move. That's why they have been collected, most of them collected are juvenile. Okay, so this is one of the very rare photos that you can see the clear fish inside the water. I think this was taken from Japan, but I got this from the website, I could not find the locality, but this one is quite okay. I mean, this is the expectation. Okeanos, the NOAA expedition so they filmed this one, but this one is a different subfamily. They belong to Paralepididae, but they can be separated into two different families.

And this, I want to show you a video. I suppose this is the only one video in history. So you look at this area here and look here. And then it comes to this area. So, this is a Paralepididae. Very, very cute. Okay, so suppose this is the only video that we can see of this fish for the whole history.

Okay, so what is Barracudina? These fish are quite similar to many Aulopiformes. But it's quite interesting that this one has a dorsal fin sit behind, and dorsal fin and pelvic fin sit behind, and they have a quite long anal fin base. And also they have quite a large number of vertebrae, but they can be separated into two subgroups. So they have two different ranges. Yeah, they have the adipose fin, like many Aulopiformes.

So this is the first group. Traditionally, the family can be divided into two subfamilies. Some people actually just call them two different families, but here we give a bigger concept, so we actually just call that Paralepididae. And the first group is the subfamily. we can call that subfamily Paralepidinae, and that have multiple rows of gill rakers. So this is the gill raker on the gill arch inside the gill cover, and they also have four scale. The body cover four of scales. However, the scales are kind of, can be lost easily. So sometimes you get misled by the scale, because it's sometimes very hard to see if there is scale or not. But the lateral line always have scale. But if you look at the gill raker, it's become very easy. This group include four genera. So basically, genera are quite similar, and that was reviewed by Post. So this group has less problems, except we just described a new species later, I will show you.

And this is another subgroup. We can call that a family or a subfamily Lestidiinae. And Lestidiinae have only a single row of the teeth on each gill raker. So this, if you open the gill cover, then you can see. This group is far more complicated. Yeah, because there are seven genera now, and roughly 55 species. However, as you can see the question mark here, and I will explain a little bit more about what happened to this.

This is a brief history of the group. So the genus was established by Cuvier. And then there's a type species that was recognized later. After a long time, nearly 100 years, from Copenhagen, so he studied fish, larvae, and juvenile, and he found many interesting things. But at that time, no one was really working on this group. So he started to work on this group, and based on only larvae and juveniles. And in about 40 years, he described 29 new species, all based on larvae and juveniles. And interestingly, he never compared them to the adult specimen. So this caused a very, very large problem, because the larvae and juveniles do not have the adult character. And it's so difficult to match them, because they change their body proportion, they change everything with growth. Anyway, Maul, he started to work on this, and then he also described some new species. Actually, some of his new species are not so clear. And then very soon, Harry from United States, and later on, he called himself Rofen – so basically, this is the same person – he started to work on the genera and tried to separate them one by one. And he established many genera that was established as a subgroup, as a species group. And then he described 11 new species. Later on, Post, he's the last one working on this group, really focused on this group, he described new genus and six new species. After that, about a 14 year gap, the Japanese, they describe a new species based on juvenile again. And after 2004, there's no one really working on this group, not even a new species or not even a re-description of the name. And most people consider this group so difficult, because the juvenile confusion. Anyway, about half of the species are described based on only juvenile. So this is very, very difficult for us.

Is there a diagnostic character for each genera of Paralepididae? The answer is no. There is no general key to genera. So most of the characters actually overlap. However, we still can, based on Harry/Rofen, we still can get some good information of some I call ‘simple genera’.

So this is the beginning that we start from Taiwan. So look at, if you look at them carefully, actually there are many different things. For example, this one has a snout, this one, this one had long snout, , long snout. This one has snout, this one had quite pale. And this one had a dark colour on the torso. So these three are actually quite different. And then we also have this, they have a light organ, this one had a light organ, and this one had a short snout, and this one had a black snout. So one by one, we actually can find at least to the genus, and then some of them we can match them to the species. Lestrolepis japonicus is the most common species. I would say 90% of the specimens we call japonicus.

With this suspicion that we think that maybe we should do something for our species, we start in Taiwan and this is the fourth one I call a simple genus. Lestrolepis, why? Because they always have a light organ, even when they are very small, like 33 centimetres, 30 millimetres, they already grow this. And this is the light organ and when they become larger, they actually have another light organ, this is a luminous duct, that’s inside the belly. But from the outside, you can see that they divide into two branches. So this genus is relatively simple.

And this one is Macroparalepis. This one is also simple because the anus is far away from the anal fin. So usually, they don't have an adipose fin like this one. This is called a ventral adipose fin. This is dorsal adipose fin. And this is the position of anus in Stemonosudis. That one is most of the genera have the anus quite close to the pelvic fin. But the Macroparalepis have the anus far away. OK, so it is quite easy to separate this genus. And this one doesn't have light organ.

And it gradually becomes more and more difficult. Stemonosudis or Dolichosudis, these are actually two valid genera now. However, when we work on them, actually, basically, these two genera are the same. So this is Dolichosudis fuliginosa and this one is diagnosed by the dark colour, the bright colour. However, we found several species across the different genera that have bright colour in adults, so this cannot be a good diagnostic character. And another character is the nostrils. It's actually situated right above the posterior end of maxilla. This is a good character because most of the species have the nostrils before the end. However, we found the Stemonosudis still have some nostrils more behind or quite anterior, like here. So far, there is no good character to separate Stemonosudis and Dolichosudis. At least some of the genera, they are quite confused.

And this is the most difficult one, Lestidiops. Roughly 15 to 20 species, there are a bit more than 20 names. Some of them have been synonomized. And basically, this one does not have any single diagnostic character. So everything we use is a combination of character present or absent in all the other genera. So this is so difficult for us to do the research, especially this group.

Just to give you some examples. These are all Lestidiops and most of them are described based on juvenile. As you can see, the juvenile has very short snort and smaller head. This is an Indian Ocean species, jayakari. Basically, this is the first species described. So this should be the varied species, but there is no type specimen. That means we cannot track back what is the true jayakari. And in the Atlantic Ocean, there are at least six different names that are similar to jayakari. So basically, they have some small differences. It's the vertebrate number, but they are overlaid. So I haven't got any ideas to solve this problem.

And from the literature, actually, we know the vertebrate number, the position of fins, the position of the anus, and the lateral line are important characters. For example, if you see the original dorsal fin, original pelvic fin, you can see this species is quite far away. This species is quite close. Some of them have the pelvic fin origin, actually, is behind the origin of dorsal fin. The anus is kind of, see, the anus is before the dorsal fin. The anus is behind the dorsal fin. And then this is the lateral line. This is what I call a complete lateral line. So the lateral line goes all the way to the caudal fin base. And then the lateral line goes to just above the middle of the anal fin base. So we got some very good characters from the history. However, it's very hard to quantify the fin position, except for you just measure to them, otherwise, it's so difficult. But we know that. This is the scale, the lateral scale. And if you stand them in red colour, you can see the clear scale. And you can count the number quite easy. So in most cases of fish, the vertebrae is related to the myomeres. And the myomeres is related to the lateral scale. So this is my idea, our idea that maybe we can count the lateral line scale. And then we can compare that to the vertebrae number and see what happens. And then, because I want to quantify the fin position, I want to use the lateral line scale to represent this position. So this kind of character was used in Anguilliformes in eels, quite common. And I also work on Anguilliformes a bit. That's why I borrowed this kind of character.

And we also count hundreds, I think several hundreds, of X-ray to understand the vertebrae number before this position, the dorsal fin origin, and pelvic fin origin. Of course, we also count the total vertebrae. So in this case, you can see the dorsal fin origin and the pelvic fin origin are quite close. The dorsal fin and the pelvic fin origin are quite far away. Actually, we can also count the difference of the vertebrae between these two. Then you can actually separate the species.

Yeah, so this is the result and also the test because we want to know if these two numbers match to each other. So, good. We got a very good result. This is a new species we described, the lateral line scale and the vertebrae. So as you can see, the lateral line scale and vertebrae are actually, they fit to, they match each other, especially the majority. Again, intermedia another species and pofi. So these are four species belong to Lestrolepis. These are four species belong to the Lestidium. OK, but nudum is more difficult because we only have three specimens. So we can count many numbers. So you can see still slightly different. However, if you put them here, actually some of the number, this is pre-dosal lateral-line scale and Predorsal vertebrae. You can separate the species and they also match to each other quite well. This is Preanal. Yeah, again, they match to each other. And also you can separate the species.

OK, so we got a very important finding. Actually, the lateral line scale, predorsal, prepelvic, preanal, lateral line scale is actually quite close to predorsal and prepelvic and preanal vertebrae. So by counting the lateral line scale, we can predict the vertebrae number and also the fin position. Then we can separate species quite well. So by using this character, this is the new character. So we can start to work on them.

So this is the first species we described and we found a species from South Hemisphere, very close to Antarctic. And the species have a more slender body. And the pelvic fin origin is way up behind the dorsal fin. So another species result that found in all around the world, especially in Atlantic Ocean. So you can see the fin position slightly different. The nose is slender in the new species. This is the distribution map in the island. I don't know how to spell it, but it's quite close to Antarctic. And the result is also supported by the DNA barcoding.

So then the next one is the Lestrolepis. This one is still easy – remember, I said that there is a light organ here. And there is a species that have been put in the Lestrolepis leutkeni. I mean, have been called leutkeni for a long time. But when I examine the holotype of leutkeni, it's actually a Lestidiopus, a different genus, not a pofi. Because they called leutkeni as a valid species in the Lestrolepis. So they’ve seen pofi. And we found that actual pofi is a new, a valid species. And interestingly, in 1977, they report a species, a pofi from Red Sea. And I am interested in that species. So I borrowed a specimen and we found that it's actually different from the true pofi and the true leutkeni. So we described that as a new species.

And this one is another Lestrolepis case, three species and two species from Taiwan. And interestingly, for a long time in Japan, in many places, they call it intermedia. I mean, in Western Pacific, they call that intermedia. However, the type specimen, the type series of intermedia is actually from Western Atlantic, nearby the Caribbean Sea. So it's too far away. And I always think that maybe there's something wrong so we did a genetic test. We also used the meristic data.

So this is the new species we described. This is intermedia, I mean, this is intermedia from Western Pacific. This is from Atlantic. So you can see how different they are. This is the abdominal vertebrae. This is prepelvic vertebrae. This is preanal vertebrae. And then also, the lateral line scale are actually different. So based on this character, we actually we describe a new species. This is from Taiwan and also from Western Pacific. And in the next case, this is also, I call an easy genus, Lestidium. Again, a species called atlanticum that occurred in Western Pacific in Japan and Taiwan and I thought that maybe this is not right. And another species previously called nudum in Western Pacific. Nudum was described from Hawaii so that makes sense, actually. And then prolixum is actually described from Japan. But with the doubt, I actually looked at the specimen. And I looked at the specimen of nudum and atlanticum. And again, actually, we can separate them quite well. So we described two new species.

And this is another case from Australia. This is longilucifer. It's very, very similar to atlanticum. That is the third species in that complex. What is the complex? What is the character for a complex? This is the light organ, the luminescence duct. So the light organ go all the way to the chin area. Most of the species only go to the pectoral girdle. So this is quite long. That's why I call it longilucifer. And this is another species we found in the atlanticum complex. So one species from Taiwan and Japan, and another species from Taiwan and Australia. And the third species is atlanticum from Atlantic Ocean. And this one is quite similar to prolixum. But we found still there are some differences. So we describe that as a new species. So there is a species from Japan, prolixum, another species from Australia, nigrorostrum. And if you look at the meristic data, so we can separate them roughly into two groups. So this is atlanticum group. This is prolixum group. So this character actually is quite good to separate them. And all the new species are supported by the DNA barcoding.

And this is another complex, Stemonosudis. So as I said, Stemonosudis is quite difficult. So we just separate, we just solve some problem that we can do. But there are still some other problems we cannot do. So this is the Stemonosudis rothschildi. Before, we have only one species. They have one, two, three, four, I think nine blotch on the dorsal fin, on the dorsal area. And then this is a new species that have many, many more. It is the 10th before the dorsal fin base. And also they are quite different in the vertebrae number. Then we found another species that is quite interesting because the dorsal fin shifts really behind. It's actually nearly the same vertical of the anal fin. So you can see the pelvic fin and dorsal fin are quite far away. We call this retrodorsalis. So Post actually discovered this species already but he thinks that maybe it's only the variation of the species. Here we found five additional specimens from the past in Japan, but it's also correct from Indonesia. So we reviewed this complex and then described two new species.

And then the next one we worked on is, we try to match the adult to juvenile. As I said, many species were described as only juvenile. So we actually don't know what their adult looks like. But we can only track back from some of the character. I mean, for example, like this one, the pelvic origin is distinct clearly behind the dorsal fin. This is a rare status in Lestidiops. So we found one specimen from the Australian Museum that correct from Philippines. So you can see the dorsal fin position and the anal fin position. This is the end of the dorsal fin base. This is pelvic fin origin. So basically, this is very small evidence but since we don't know what's true, so we actually just match them from some more clear, most clear character. So we describe that and it's a set. And this is the only known specimen. Here we found another one from Indonesia.

Again, this is called elongata. And these species have more than 50 anal fin ray. Most of the species have less than 40. So this species is actually quite easy. Another specimen found in MV, the Victoria Museum. So we got only four or five specimens. But it's quite good because we can match them to only one species based on the anal fin rays. And also, we also found that the adult, the juvenile is pale. And then adult changed to dark colour. So that's why we think that the bright colour is no longer a good character. This time, again, this is the position of the fin and the anus. And it actually matched to the original description quite well. And we found a good character to separate it from all the other species, is the lateral line scale. The lateral line is actually complete. So that runs to the caudal fin base.

And this is recently we are working on two species that have almost the same fin position. So one is indopacificus, the other one is mirabilis. Sorry, this is not quite in good shape. And for a long time, many people actually identify a species called indopacificus. But none of them are true indopacificus because none of them match to the original description. Here recently, we found two specimens from Taiwan. And initially, I actually identified that as mirabilis because mirabilis is the only species that have the pelvic fin or just right below the dorsal fin. But I think it's quite strange because this one is quite pale. Yeah, basically, the adult is completely break in mirabilis. This is common but quite rare to see the specimen. Only like a handful specimens we can see. Anyway, and then I look at the details and I also use the scale, use all the meristic data. We actually can separate these two species. And these species can be matched to the indopacificus. Only the species. Yeah, so these are kind of say easy, maybe not so easy but these are easy ones.

So I want to have some summary here. It's that the new character we used to separate the species and they can separate species quite well. Yeah, and the separation of species is actually supported by the DNA barcoding. So that gives us the confidence to do more by using the meristic data because those juvenile types do not have DNA data so we cannot match our specimen to the type specimen. So the only thing we can do is to use the DNA to separate the species, we think they are different. And there are still a large amount of specimens without correct identification in the raw collection. And there are still many species only known from juveniles and we are working on it. So there is still a long way to go. And I will say that do not describe new species with juveniles. Otherwise, we have to spend more time, really, we have to spend a lot of time to think about which one is which. When we see an adult, we have to think about, there should be the name matched to this one. We cannot just describe the adult as a new species and ignore all the juveniles. So this is basically my talk today.

And also, Amanda asked me that maybe I should mention a little bit about the other species, especially Lophiiformes, the anglerfish from Australia. So when I go back to look at the paper we published, we actually found many new things from Australia. Not necessarily new species, but they have been described before, like mulleus and then russatus. These two originally described from New Zealand. I think we put some type from Australia. nebulosus described from Australia. reticulatus also from New Zealand and Australia. Now, nudiventer from New Caledonia and later found from Australia. And gomoni, this is described after Martin Gomon, our good friend. And this is another group called Helicmetus. Sorry, I did not put the genus name. In 2008, I described new species from Australia and Japan, Taiwan, and Australia. And later on, we do a review. So the review results in six species from Australia. And this is the one Amanda just mentioned. We reviewed Malthopsis from Australia and described five new species. So this is a distribution map. So by using the distribution, I think the other ichthyologists or ecologists, they separated Australia into many, many sections along the coastline. So that can help the conservation, help the protection of the species. So happy to contribute to this and thank you very much for the invitation. I also thank the support of the Australian Museum.

The Barracudina family Paralepididae are found worldwide, mainly inhabiting deep pelagic waters of the outer continental shelf and slopes and are important food for whales and swift predators. The family comprises 11 genera, with about 70 species, although some genetic studies separate it into two or more families.

As many species were described from juveniles, the taxonomy of this group is especially difficult, and the adult morphology is lacking for many species. We examined specimens around the world and evaluated the diagnostic characteristics for identifying species. New species were described with new characteristics and supporting genetic data. Moreover, adults of many species have been found and redescribed to fill the gap. The diversity of Australian Barracudinas is also introduced in this talk.