Thursday, March 23, 2023

[Invertebrate • 2022] Yoda demiankoopi • A New Species of Deep-sea torquaratorid enteropneust (Hemichordata): A Sequential Hermaphrodite with Exceptionally Wide Lips

Yoda demiankoopi
Holland, Hiley & Rouse, 2022

Specimens of a new species of torquaratorid acorn worm (Hemichordata, Enteropneusta) were video recorded and subsequently collected at abyssal depths in the eastern North Pacific at sites ranging from Oregon to northern Mexico. These worms are described here as Yoda demiankoopi n. sp. by molecular and morphological methods. The new species differs from its only described congener, Yoda purpurata, in three ways. First, the lips are extremely wide and indented by a deep ciliary groove for ingesting substrate and conveying it to the mouth. Second, a connective tissue bulge of unknown significance runs mid-dorsally along the hepatic and posthepatic regions of the intestine. Third, the posthepatic intestine is strikingly sinuous and packed with gut contents presumably undergoing digestion for extended periods between infrequent defecations. Yoda demiankoopi n. sp. is hermaphroditic, a character so far known only for the genus Yoda in the entire class Enteropneusta. The gonads of each adult worm comprise hundreds of ovaries (each containing a single oocyte) and hundreds of testes located just beneath the dorsal epidermis of the anterior trunk and associated genital wings. In any given animal, at any given time, gametes of only one sex or the other become fully mature. Thus, the worm is a sequential hermaphrodite, alternately spawning purely as a female or purely as a male.

Keywords: deep-sea, Enteropneusta, Hemichordata, hermaphroditism, Torquaratoridae

Yoda demiankoopi n. sp.
(A) Living holotype SIO-BIC H51. (B) Specimen SIO-BIC H50, showing lateroventral folds (lf), genital wings (gw), and most posterior gill pores (arrowhead).
(C) Dorsal view of holotype soon after reaching the deck; arrow indicates dark hepatic intestine; arrowhead indicates mid-dorsal connective tissue bulge. Broken-off proboscis is at top right. (D) Ventral view of foregoing with ciliary groove (arrowhead) on ventral side of lip.
 Images 4A and 4B captured by Schmidt Ocean Institute's ROV SuBastian on cruise FK210726. Images owned by SOI. 
Scale bars: A = 5 cm; B = 1 cm; C,D = 2 cm

Yoda demiankoopi n. sp. Holland, Hiley & Rouse 2022
Diagnosis: This species of Yoda has the proboscis, collar, and genital wings with a deep brownish purple color, which continues with fading intensity along the posterior body. Neck ridges and nuchal protuberances are absent. The collar has extremely wide, non-tapered lips. The posthepatic intestine, in the last third of the body, shows a marked sinuosity. Adults are simultaneous hermaphrodites.

Etymology of species name: Latin masculine genitive noun demiankoopi. The name commemorates Dr. Demian Koop of the University of Sydney, a passionate developmental biologist and exceptional scientist whose very untimely death in 2021 has been keenly felt by his friends and colleagues all over the world.

Nicholas D. Holland, Avery S. Hiley and Greg W. Rouse. 2022. A New Species of Deep-sea torquaratorid enteropneust (Hemichordata): A Sequential Hermaphrodite with Exceptionally Wide Lips. Invertebrate Biology. 141(3); e12379. DOI: 10.1111/ivb.12379