Систематика и распространение живоглотовых рыб рода Pseudoscopelus (Chiasmodontidae)

A.N. Severtsov’s Institute of Ecology and Evolution,
Russian Academy of Sciences
Atlantic Research Institute of Fisheries and Oceanography
A.M. Prokofiev, E.I. Kukuev
SYSTEMATICS AND DISTRIBUTION OF
THE SWALLOWERFISHES OF THE GENUS
PSEUDOSCOPELUS (CHIASMODONTIDAE)
KMK Scientific Press Ltd.
Ìîscow  2007

Prokofiev À.Ì., Kukuev E.I. Systematics and distribution of the
swallowerfishes of the genus Pseudoscopelus (Chiasmodontidae).
Moscow: KMK Scientific Press Ltd. 2007. 162 p.
The systematics and distribution of the swallowerfishes of the genus
Pseudoscopelus are discussed. Thirteen valid species of this genus
are recognized, two of which, P. albeolus Prokofiev et Kukuev and
P. vityazi Prokofiev spp. n., are described as new, though more of the
undescribed species seem to still exist. P. albeolus sp. n. appears to
be closely related to the P. astronesthidens–superspecies but differs
from all the known members of the genus in the uniformly whitish
coloration of the body and photophores. P. vityazi sp. n. appears to be
most closely related to P. altipinnis but differs from all the known
members of the genus in the presence of trough-like bands of luminescent tissue instead of serial photophores. The nominal genus Myersiscus Fowler, 1934 is a synonym of Pseudoscopelus, and P. microps Fowler, 1934 is a synonym of P. altipinnis Parr, 1933. The
status of the recently described P. pierbartus Spitz et al., 2007 is
discussed; this species is considered to be species inquerenda and
nomen dubium, but perhaps it is a synonym of P. scriptus or P. sagamianus. The variability and diagnostic value of the characteristics
useful for the species delimitation of Pseudoscopelus are discussed.
A revised key of species is given.
Reviewers: N.V. Parin, Corresponding Member of the Russian
Academy of Sciences
S.A. Evseenko, Dr. Sci. (Biol.)
Editor in Chief: Yu.Yu. Dgebuadze, Corresponding Member of the
Russian Academy of Sciences

ÐÎÑÑÈÉÑÊÀß ÀÊÀÄÅÌÈß ÍÀÓÊ
Èíñòèòóò ïðîáëåì ýêîëîãèè è ýâîëþöèè
èì. À.Í. Ñåâåðöîâà
Àòëàíòè÷åñêèé íàó÷íî-èññëåäîâàòåëüñêèé èíñòèòóò
ðûáíîãî õîçÿéñòâà è îêåàíîãðàôèè – ÀòëàíòÍÈÐÎ
À.Ì. Ïðîêîôüåâ, Å.È. Êóêóåâ
ÑÈÑÒÅÌÀÒÈÊÀ È ÐÀÑÏÐÎÑÒÐÀÍÅÍÈÅ
ÆÈÂÎÃ
ËÎÒÎÂÛÕ ÐÛÁ ÐÎÄÀ PSEUDOSCOPELUS
(CHIASMODONTIDAE)
Òîâàðèùåñòâî íàó÷íûõ èçäàíèé ÊÌÊ
Ìîñêâà  2007

Ïðîêîôüåâ À.Ì., Êóêóåâ Å.È. Ñèñòåìàòèêà è ðàñïðîñòðàíåíèå
æèâîãëîòîâûõ ðûá ðîäà Pseudoscopelus (Chiasmodontidae). Ì.:
Òîâàðèùåñòâî íàó÷íûõ èçäàíèé ÊÌÊ. 2007. 162 ñ.
Ðàññìîòðåíû ñèñòåìàòèêà è ðàñïðîñòðàíåíèå æèâîãëîòîâûõ ðûá
ðîäà Pseudoscopelus. Òðèíàäöàòü âèäîâ ýòîãî ðîäà ïðèçíàíû
âàëèäíûìè, èç íèõ äâà (P. albeolus Prokofiev et Kukuev è P. vityazi
Prokofiev spp. n.) îïèñàíû êàê íîâûå, õîòÿ ìîæíî ïðåäïîëàãàòü
ñóùåñòâîâàíèå áîëüøåãî êîëè÷åñòâà åùå íåîïèñàííûõ âèäîâ. P.
albeolus sp. n. ïðåäñòàâëÿåòñÿ áëèçêî ðîäñòâåííûì íàäâèäó “P. astronesthidens”, íî îòëè÷àåòñÿ îò âñåõ èçâåñòíûõ âèäîâ ðîäà
îäíîòîííî áåëåñîé îêðàñêîé òåëà è ôîòîôîðîâ. P. vityazi sp. n.
ïðåäñòàâëÿåòñÿ íàèáîëåå áëèçêèì ê P. altipinnis, íî îòëè÷àåòñÿ îò
âñåõ èçâåñòíûõ âèäîâ ðîäà íàëè÷èåì æåëîáîîáðàçíûõ ïîëîñ
ñâåòÿùåéñÿ òêàíè âìåñòî ñåðèéíûõ ôîòîôîðîâ. Íîìèíàëüíûé ðîä
Myersiscus Fowler, 1934 ÿâëÿåòñÿ ñèíîíèìîì Pseudoscopelus, à âèä
P. microps Fowler, 1934 ñèíîíèìèçèðîâàí ñ P. altipinnis Parr, 1933.
Îáñóæäåí ñòàòóñ íåäàâíî îïèñàííîãî P. pierbartus Spitz et al., 2007;
îí ïðèçíàí species inquerenda è nomen dubium, íî, ïî-âèäèìîìó,
ÿâëÿåòñÿ ñèíîíèìîì P. scriptus èëè P. sagamianus. Ðàññìîòðåíû
èçìåí÷èâîñòü è äèàãíîñòè÷åñêàÿ çíà÷èìîñòü ïðèçíàêîâ, âàæíûõ
äëÿ âûäåëåíèÿ âèäîâ Pseudoscopelus. Äàí ðåâèçîâàííûé êëþ÷ äëÿ
îïðåäåëåíèÿ âèäîâ.
Ðåöåíçåíòû: ÷ëåí-êîðð. ÐÀÍ Í.Â. Ïàðèí
ä.á.í. Ñ.À. Åâñååíêî
     Îòâ. ðåä.: ÷ëåí-êîðð. ÐÀÍ Þ.Þ. Äãåáóàäçå
Èçäàíèå ïîääåðæàíî Ïðîãðàììîé ôóíäàìåíòàëüíûõ èññëåäîâàíèé
Ïðåçèäèóìà ÐÀÍ “Áèîðàçíîîáðàçèå è äèíàìèêà ãåíîôîíäîâ”
ISBN 978-5-87317-447-8
© Ïðîêîôüåâ À.Ì., Êóêóåâ Å.È.,
òåêñò, èëëþñòðàöèè, 2007
© Òîâàðèùåñòâî íàó÷íûõ èçäàíèé
ÊÌÊ, èçäàíèå, 2007

CONTENT
1. Introduction ............................................................................... 6
2. Materials and methods............................................................... 9
3. Guide to the morphological characteristics valuable for
   definition of Pseudoscopelus species .......................................13
4. Systematic descriptions.............................................................36
4.1. Pseudoscopelus altipinnis Parr, 1933 .............................36
4.2. Pseudoscopelus aphos Prokofiev et Kukuev, 2005 ........46
4.3. Pseudoscopelus astronesthidens–superspecies .............51
4.4. Pseudoscopelus astronesthidens Prokofiev et Kukuev,
      2006 ...................................................................................53
4.5. Pseudoscopelus australis Prokofiev et Kukuev, 2006....63
4.6. Pseudoscopelus albeolus Prokofiev et Kukuev, sp. nova ...69
4.7. Pseudoscopelus parini Prokofiev et Kukuev, 2006 ........76
4.8. Pseudoscopelus cephalus Fowler, 1934 .........................81
4.9. Pseudoscopelus scriptus–superspecies ..........................87
4.10. Pseudoscopelus obtusifrons (Fowler, 1934) .................89
4.11. Pseudoscopelus scriptus Lütken, 1892 .......................102
4.12. Pseudoscopelus sagamianus Tanaka, 1908................ 112
4.13. The status of Pseudoscopelus pierbartus Spitz et al.
        (2007) ............................................................................121
4.14. Pseudoscopelus stellatus Beebe, 1932 .......................122
4.15. Pseudoscopelus scutatus Krefft, 1971 .......................126
4.16. Pseudoscopelus species ..............................................135
5. Key to the species of Pseudoscopelus known to date ..........137
6. General remarks on distribution of the Pseudoscopelus
    species ....................................................................................140
7. Acknowledgements.................................................................141
8. References .............................................................................142
9. Addendum ...............................................................................149
9.1. Pseudoscopelus altipinnis Parr, 1933 ...........................149
9.2. Pseudoscopelus sagamianus Tanaka, 1908 .................152
9.3. Pseudoscopelus vityazi Prokofiev, sp. nova .................158

1.  INTRODUCTION
The swallowerfishes of the genus Pseudoscopelus Lütken, 1892 are
the most diverse lineage of the chiasmodontids (Lavenberg, 1974;
Prokofiev, Kukuev, 2005, 2006a, 2006b, 2006c), which can be distinguished by characteristic jaws dentition, by peculiarly striated and cancellated cranial roofing bones, and, as a rule, by the presence of the
serially arranged photophores (except P. aphos and P. parini –
Prokofiev, Kukuev, 2005, 2006b), which is unique within all the acanthopterygians.
The first specimen of the linebellies, taken from the Old Bahamas
Straits in the Western North Atlantic, was identified by Lütken (1892),
who named a new genus and species, Pseudoscopelus scriptus, and described a number of “mucous pores” arranged in discrete series on the
head and body of this fish. Later, Tanaka (1908) identified a new subspecies, P. scriptus sagamianus, from the Sagami Bay on the Pacific
coast of Japan. In the first formal revision of the chiasmodontids, Norman (1929) synonymized these two taxa, as the diagnostic characteristics listed by Tanaka (1908) were insufficient for the species delimitation. However, few specimens of Pseudoscopelus were collected at that
time, and a Pseudoscopelus specimen examined by Norman actually
belonged to another species, P. altipinnis (Parr, 1933: 41). Subsequently, five nominal species and a new genus (Myersiscus) of linebellies
were described from 1932 to 1934. Beebe (1932) was the first to detect
the light production of the so-called “mucous pores”; he reported the
clear bright green (“night green”) bioluminescence of these “pores” in
his description of P. stellatus, and he named these “pores” photophores
(op. cit: 77). Parr (1933) described a new species, P. altipinnis, from the
Western North Atlantic and provided a key for the species identification. Fowler (1934) described a new genus and three new species (P.
cephalus, P. microps and M. obtusifrons) from the Albatross collections
obtained off the Philippines and Indonesia.
Although between 1892 and 1934 the number of known species of
linebellies increased to seven, the identification of these species was
problematic because the original reports contained very little information, lacking, in some cases (e.g., Fowler, 1934), descriptions of really
diagnostic characteristics. In most reports devoted to advancing the study
of oceanic ichthyofauna, the Pseudoscopelus species usually were defined as P. scriptus or Pseudoscopelus sp., and it is obviously impossi

1. Introduction
7
ble to determine their real species attribution without examination of
specimens today. However, Krefft (1971) described a highly distinctive
new species, P. scutatus, from the tropical and subtropical Atlantic. Furthermore, Kukuev (1982) had found several differences in the coloration, proportions, modal counts of fin-rays and in the photophore pattern between two groups of Pseudoscopelus spp. from the North Atlantic, and separated them under the names P. scriptus and P. altipinnis.
However, none of these authors specially investigated the systematics
of this genus.
Smith (1965) suggested that the photophore-bearing swallowers deserve full family rank. Although this hypothesis became very popular,
there is no evidence, aside from the light organs, supporting Smith’s
suggestion at present (see also Lavenberg, 1974: 5)1.
None of the fossil records of Pseudoscopelus is known. Daniltshenko (1960) identified Myersiscus grossheimi from the Lower Oligocene
(Chadumian) of the North Caucasus, but Lavenberg (1974) excluded
this species from the Chiasmodontidae. Recently, Bannikov (1998) transferred M. grossheimi to the genus Champsodon of the family Champsodontidae.
The first work devoted to the revision of Pseudoscopelus was prepared by Lavenberg (1974) as his Ph.D thesis. Lavenberg presented various data about osteology, distribution, relationships and some aspects
of biology of this genus; redescribed and discussed eight previously
known species and proposed six new species. In addition, he was the
first who discovered the Pseudoscopelus specimens completely lacking
photophores. Although, in our opinion, Lavenberg’s thesis is not free
from mistakes, it was a framework for the future investigations of the
1 Smith (1965) described a peculiar juvenile chiasmodontid, Gargaropteron
pterodactylops, and proposed a new subfamily for this fish. Subsequently, Johnson
and Cohen (1974) found that Gargaropteron is the larval stage of Kali; thus,
subfamilial categories are not warranted. However, despite some common
characteristics of larvae of the chiasmodontid genera Chiasmodon, Pseudoscopelus
and Kali plus Dysalotus (e.g., the similarly structured spinules covering all the body)
there are peculiar differences between the larvae of the aforementioned three generic
groups (S.A. Evseenko, personal communication 2006). Fitch and Lavenberg (1968)
also found some differences in the otolith structures of Pseudoscopelus and species
of Chiasmodon and Kali. However, before a detailed morphological investigation
of the chiasmodontids is undertaken, any high-level taxonomic changes seem to be
premature.

À.Ì. Prokofiev, E.I. Kukuev. Swallowerfishes of the genus Pseudoscopelus
Pseudoscopelus and chiasmodontid systematics, phylogeny and ecology. Unfortunately, however, it was never published. Recently, Prokofiev
and Kukuev (2005, 2006a, 2006b) reviewed the linebellies of the Atlantic Ocean, briefly discussed the status of all the species within this
genus and described two new species from the Western Atlantic and
Western Pacific that lack photophores. However, because we were unable to examine types of P. altipinnis at that time, we misidentified this
species with an undescribed superspecies complex, which was lately
described as P. astronesthidens–superspecies, with two closely related
allopatric species that have antitropical distribution (Prokofiev, Kukuev, 2006c). The true P. altipinnis was described under the name P. microps – a junior synonym of the former (Prokofiev, Kukuev, 2006c) –
by Prokofiev and Kukuev (2006a). Finally, one more new species, P.
pierbartus, from the Gulf of Gascogne (Eastern Atlantic), was identified by Spitz et al. (2007); these authors also discussed the status of
other nominal species and synonymized P. microps with P. altipinnis
and P. cephalus with P. scriptus, and noted the possible separation of
Pseudoscopelus into its own family.
After our previous publications had already been submitted or published, we successfully obtained many additional specimens of Pseudoscopelus, which gave us the opportunity to extend our knowledges of
the composition, variability and distribution of the species of this genus. We have summarized these new data in the present paper. In addition, we identified a new species from the Antarctic, which was formerly reported by us under the name Pseudoscopelus sp. A (Prokofiev, Kukuev, 2005). At present state of knowledges, we believe we are justified in
describing a new species based on this specimen. Certainly it is not a
final contribution in Pseudoscopelus systematics, as several species are
represented by very limited material, and the fauna of the linebellies of
the Indo-Pacific is still poorly known. Moreover, we are unable to define three undescribed species mentioned by Lavenberg (1974) in our
materials, so we believe that the number of species in the genus will
increase in the future. However, we hope that the present contribution
will support future research in Pseudoscopelus systematics.

2. Materials and methods
The specimens examined for the present study are listed in the systematic descriptions. In total, 106 specimens of all the described species of Pseudoscopelus were examined. All the specimens were radiographed. For IID and A the total number of elements (branched and
unbranched rays) was counted, as the tips of anterior rays of these fins
are often damaged and the real number of unbranched rays can be miscounted easily in such cases. The number of unbranched rays in IID and
A is not a diagnostic characteristic and varies from one to three or four
rays in most species of Pseudoscopelus. The measurements follow
Prokofiev and Kukuev (2006c) and are explained in figs. 1 and 2. All
the specimens examined were measured; however, some of the measurements could not be accurately taken due to abdominal-cavity distensions (e.g., H, VA, an-A) or damaged structures (e.g., fin rays) in
some fishes. The canals of the laterosensory system were investigated
by injection of Cyanine Blue R into the canals. The structure, nomenclature and methods of investigations of various morphological characteristics useful in the study of the Pseudoscopelus species are described
in detail in the section “Guide to the morphological characteristics” (see
below).
Abbreviations used in the text are as follows:
Fins and counts: ID, IID, A, P, V and C – first and second dorsal,
anal, pectoral, pelvic and caudal fins, respectively; sp.br – number of
gill-rakers on first gill arch; r.br – branchiostegal rays; vert – vertebrae.
Measurements: SL – standard length; lc – head length; ao – snout
length; oo – horizontal diameter of orbit; ho – vertical diameter of orbit;
io – width of interorbital space; n1-o and n2-o – distances between anterior margins of the first and second nares to the anterior margin of the
orbit rim; sub – suborbital depth; lmx – upper jaw length; lmd – lower
jaw length; ipm – interpremaxillary distance; wc – head width at the level
of uppermost preopercular pore; lop – length of opercular lobe; H – greatest
body depth; h – least depth of caudal peduncle; lcp – caudal peduncle
length; aD1, aD2, aA, aP and aV – first and second antedorsal, anteanal,
antepectoral and anteventral distances, respectively; VA – ventro-anal
distance; lP, lV and lC – length of pectoral, pelvic and caudal fins, respectively; lD1, lD2, lA – length of first and second dorsal and anal fin
bases, respectively; hD1, hD2, hA – length of longest ray of first and

À.Ì. Prokofiev, E.I. Kukuev. Swallowerfishes of the genus Pseudoscopelus
1
2
Figs. 1, 2. Measurements for the swallowerfishes of the genus Pseudoscopelus.
Explanations: 1–2, standard length (SL); 1–3, length of head (lc); 4–7, greatest depth
of body (H); 10–11, least depth of caudal peduncle (h); 9–10, caudal peduncle length
(lcp); 1–4, first predorsal length (aD1); 1–5, second predorsal length (aD2); 1–6,
prepectoral length (aP); 1–7, prepelvic length (aV); 1–8, preanal length (aA); 7–8;
pelvic-anal length (VA); 6–14, pectoral-fin length (lP); 7–15, pelvic-fin length (lV);
11–16, caudal-fin length (lC); 4–13, length of 1st dorsal-fin base (lD1); 5–12, length
of 2nd dorsal-fin base (lD2); 8–9, length of anal-fin base (lA); 4–17, height of 1st
dorsal fin (hD1); 5–18, height of 2nd dorsal fin (hD2); 8–19, height of anal fin (hA);
8–20, distance between the center of anus and the anal-fin origin (an-A); 1–24,
length of snout (ao); 24–25, horizontal diameter of orbit (oo); 26–27, vertical diameter
of orbit (ho); 32–32, interorbital width (io); 24–29, distance between anterior nare
and anterior margin of orbit (n1-o); 24–30, distance between posterior nare and anterior
margin of orbit (n2-o); 27–28, suborbital depth (sub); 1–21, length of upper jaw
(lmx); 22–31, length of lower jaw (lmd); 1–1, interpremaxillary distance (ipm); 3–
23, length of opercular lobe (lop); 23–23, maximum width of head (at the level of 5th
preopercular pore) (wc).