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<I>Teuthowenia</I> (Oegopsida)

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<I>Teuthowenia</I> (Oegopsida) BULLETIN OF MARINE SCIENCE, 36(1): 1-85, 1985 SYSTEMATICS, BIOLOGY AND BIOGEOGRAPHY OF THE CRANCHIID CEPHALOPOD GENUS TEUTHOWENIA (OEGOPSIDA) Nancy A. Voss ABSTRACT Teuthowenia is comprised of three discrete, closely related, allopatric species. Synonymies, definitions, diagnoses and keys to all developmental stages are presented, along with a review of the complex history of the genus and detailed illustrations. The discrete, ecologically distinct, distributional patterns of the three species reflect the influence ofa number of biological and physical factors. T. megalops (Prosch) is confined to the highly productive Atlantic subarctic and the highly productive areas of the North Atlantic temperate region. T. maculata (Leach) is restricted to the area of year-round, high productivity in the eastern tropical Atlantic. T. pellucida (Chun) is distributed circumglobally in the mixed and fringing waters of the Southern Subtropical Convergence. The species display similar patterns of ontogenetic descent from near-surface waters to midwater depths of about 1,000 m to in excess of 2,500 m where the animals mature, mate and spawn. Teuthowenia species have differentiated physiologically and developmentally as well as morphologically. Variations in the maturity-related morphological features among the species suggest differences in behavioral patterns for courtship and copulation. The genus displays a high rate of evolution in male and female secondary sexual characters. The relationships of Teuthowenia with Egea and Megalocranchia, which together comprise the monophyletic Megalocranchia group, and with the other taoniin genera are discussed. The taxonomic confusion surrounding the cranchiids was resolved in part by the familial revision of N. Voss (1980). The phylogenetic history of the family was reconstructed by N. Voss and R. Voss (1983). This first ofa proposed series of individual generic revisions elucidates the specific differentiation that has oc- curred in the various genera, the inter- and intraspecific variations in growth and development that have resulted in confusion within and among taxa, and the vertical and geographic distributions of the individual species. Teuthowenia historically has been the most confused of all the genera of the Cranchiidae. I found the distribution of the genus to extend from the subarctic region of the North Atlantic to the circumglobal waters in the region of the Southern Subtropical Convergence. North-south disjunctions in the distributional pattern were revealed by analyses of the collections from the Cape Town-Denmark transect of the 1928-1930 Round-the-World cruise of the DANAand the Cape Town-Madeira transect of the 1971 cruise of the WALTHERHERWIG,together with the results from a series of stations made by the DISCOVERYat about 10° intervals in the eastern North Atlantic between 60° and lION (Clarke and Lu, 1974; 1975; Lu and Clarke, 1975a; 1975b). The defined populations represent three discrete, closely related, allopatric species. HISTORICALREVIEW The history of the genus Teuthowenia as now recognized is complex. The first mention of a nominal species was by Leach in 1817 in the Zoological Miscellany, when he briefly characterized Cranchia maculata on the basis of a mantle of a larva collected off West Africa by John Cranch during the Tuckey Expedition to the river Zaire. The fOllowing year, Leach (1818) listed the species when he 2 BULLETIN OF MARINE SCIENCE, VOL. 36, NO. I, 1985 expanded the diagnosis of his new genus Cranchia. In 1847, Prosch created a new subgenus of Cranchia, Owenia, to contain his newly described and figured species mega lops, the larval type of which was collected off the Faeroe Islands. In the same work, maculata was again listed. A number of inaccuracies in Prosch's original description and figures of mega lops were pointed out by Morch in 1850. Six years later in a footnote in his paper on the cephalopod hectocotylus, Steenstrup (1856) briefly characterized a new species Leachia hyperborea collected high up in Baffin Bay. In his 1861 survey of the cephalopods in the collections of the Copenhagen museum, Steenstrup showed that the dorsal, pseudoarticulation of the head and mantle used by Prosch to distinguish his subgenus Owenia from Cranchia, which displays a dorsal fusion between head and mantle, was not present in the primary specimen described and figured by Prosch (1847, figs. 4-6). Steen- strup found that the error was due to the misidentification of additional larvae, one of which Prosch showed in figure 7, considered along with the primary spec- imen. The supplementary specimens, which lacked the dorsal nuchal fusion, were not identical to megalops but appeared to be young gonatids. In the same work, Steenstrup expanded the characterization of the 210-mm ML subadult type of his species hyperboreus, placed it along with Loligo pavo Lesueur in his newly proposed genus Taonius, and designated the older species pavo as the type-species. Cranchia maculata was regarded as an incompletely known species and was not listed. Later Steenstrup (1881) further clarified the Cranchia-Owenia-Gonatus confusion. About the same time, Tryon (1879) listed maculata and megalops under Cranchia and assigned hyperborea to Lamark's genus Loligopsis along with pavo which had, prior to Steenstrup (1861), been placed in Loligopsis by Orbigny in 1839. Verrill (1881) further complicated the picture by naming a new genus Des- moteuthis, on the basis of a 330-mm ML specimen from off New England that he mistakenly considered to be identical to Taonius hyperboreus (Steenstrup). Later in the same paper, a second species tenera based on two juveniles the largest measuring 116 mm ML, from off New England was added to the new genus. Subsequent to Rochebrune's (1884) transfer of hyperborea back to Lamark's Lo- ligopsis, Hoyle (1885) replaced Streenstrup's species in Taonius, and clarified the Desmoteuthis problem. Fortunately, Verrill's specimens were well described and illustrated, permitting Hoyle to recognize Verrill's error in identifying the 330- mm ML animal with hyperboreus, and to correctly identify the specimen as Tao- nius pavo. Consequently, Hoyle placed Desmoteuthis hyperboreus, Verrill in the synonymy of Taonius pavo and synonymized Desmoteuthis with Taonius. In the course of the study, Hoyle reexamined the type of hyperboreus and gave the first detailed description of the species. In addition, he tentatively placed Verrill's second species Desmoteuthis tenera in the synonymy of hyperboreus, an assign- ment fully supported by my examination of the two syntypes of tenera. The following year in the Challenger Report, Hoyle (1886) elaborated on the Taonius- Desmoteuthis problem. For the first time, Steenstrup's type of hyperboreus was figured; and additionally, after reexamining the type, Hoyle gave the first descrip- tion of Cranchia maculata, previously known only from Leach's brief character- ization given first in Latin (1817)- "sacco laevi pulcherrime nigro maculato; maculisovatis distantibus"-and then in English (1818). Pfeffer (1900) accepted Hoyle's placement of Desmoteuthis hyperborea, Verrill in the synonymy of Taonius pavo, and D. tenera in the synonymy ofSteenstrup's hyperborea, but unfortunately retained the genus Desmoteuthis for hyperborea. The nomenclatural web was further tangled by the introduction of his 1884 genus Megalocranchia which Pfeffer synonymized with Desmoteuthis. Though the type voss: REVISION OF TEUTHOWEN1A 3 of Pfeffer's type-species Megalocranchia maxima, a 39-mm MLjuvenile from off the Cape of Good Hope, is not extant, having been destroyed in World War II, the originally described, and later illustrated (Pfeffer, 1912) feature of two rows of suckers on the tentacular stalk, alone precludes membership in the genus now recognized as Teuthowenia. At the same time, Pfeffer raised Prosch's discarded subgenus Owenia to the generic level to contain megalops. Chun (1906) supported Pfeffer's concept of Desmoteuthis and Owenia but, in his 1910 monograph he proposed Teuthowenia for the preoccupied name Owenia to contain megalops, and added a new species antarctica to the genus based on a 13-mm ML larva from the Antarctic. Chun expressed uncertainty, however, as to the significance of the difference that he noted between mega lops and antarctica as to the number of rows of suckers on the tentacular stalks-four rows in the former species and two rows in his new species. This difference plus the presence of the digestive duct appendages only on the digestive gland in antarctica as originally described and figured, and confirmed by my examination of the type, rather than on the gland and digestive ducts as found in the larva and adult of Teuthowenia, suffice to show that the two species are not congeneric. In addition, Chun added a new species pellucida to Desmoteuthis, describing and figuring in detail the 77-mm ML larval type collected in the Benguela Current; and, with reservations, mistakenly placed Helicocranchia pfefferi Massy, 1907 into the syn- onymy of the genus. The previous year, Hoyle (1909) had similarly accepted Pfeffer's retention of Desmoteuthis for hyperboreus, a move in conflict with his correct conclusions previously expressed in his works of 1885 and 1886, but Hoyle differed from both Pfeffer and Chun by retaining megalops in Cranchia. Hoyle (1910) continued to so regard both hyperboreus and megalops. Again, seeking to solve the Taonius-Desmoteuthis problem, Berry (1912) came to the same logical conclusions arrived at by Hoyle in his
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