Sarsia macrogastera Xu, Chen, & Wang, 2022

Wang, Xiao, Chen, Xiao-Yin & Xu, Zhen-Zu, 2022, Two new species and four new records of the Sarsia tubulosa group of Sarsia (Cnidaria, Corynidae) from the Bohai Sea of China, Zootaxa 5189 (1), pp. 243-254 : 246-247

Sarsia macrogastera Xu, Chen, & Wang sp. nov. ( Fig. 3 )

LSIDurn:lsid:zoobank.org:act: 3D943114-89E7-4EAB-B964-29FBD4EA63CB

Material examined. Holotype ( FIO-HCCS02 ), one specimen from the Bohai Sea of China. Station 2-2 (39°55’37.98”N, 119°42’55.02”E), depth 3.4 m, July 2020, collected by Xiao Wang.

Diagnosis. Medusa subumbrella is pointed. Manubrium has a large, spindle-shaped stomach and short oral tube (about 2/3 of the manubrium). Bullet shaped apical knob present as a growth protruding up from the base of the manubrium. Radial canals are very broad, with glandular swellings; they enter the gastrodermal chambers of bulbs without passing through mesogloea. Tentacular bulbs are large, gastrodermal chambers of bulbs very shallow, epidermal part of bulb elevated relatively high, with even thickness and red ocelli.

Description: Medusa is 2.8 mm high, diameter 3.5 mm, greater in diameter than in height. Jelly relatively thick, thicker at apex with diminishing thickness towards margin. Bell top is rounded, subumbrella quite pointed, with scattered exumbrella nematocysts. Manubrium length is about the height of the bell cavity in preserved specimen, with bullet-shaped apical knob. Manubrium is divided into a short, thick serpentine part and a distal, large spindle shaped stomach part (about 2/3 of manubrium). Gonad only on serpentine part of manubrium, leaving only the stomach and the base part of manubrium uncovered (about 1/18 the bell cavity height). Radial canals broad, with glandular swellings. Radial canals enter gastrodermal chambers of bulbs in the abaxial halves, without entering mesogloea. Tentacular bulbs large, frontal view narrow relative to tentacle width, gastrodermal chambers very shallow, with straight to concave abaxial sides, but more often concave in side view ( Fig. 3C,3D ). Epidermal parts of bulbs are relatively high, with even thickness and large red ocelli. Tentacles are short, about 1/3 as long as height of medusa in preserved specimen, with nematocyst clusters arranged in rings along nearly their whole length, ending in slightly enlarged globular clusters. Colors: manubrium, apical knob, epidermal part of bulbs are yellowish.

Distribution. The Bohai Sea of China.

Etymology. The species epithet is from the Latin macrogastera , meaning large stomach. The species name refers to the morphology of the stomach, which is very large.

Remarks. Based on the structural characteristics of its medusa, this medusa can be assigned to the genus Sarsia Lesson, 1843 . This new species can be distinguished from the other species of the Sarsia tubulosa group by its pointed medusa subumbrella and manubrium lacking apical canal. It is similar to Sarsia apicula (Murbach & Shearer, 1903) which also has an apical knob, and very short base section of the manubrium that is not covered by gonad. However, this new species differs from similar species in four ways: 1) its manubrium has a large, spindleshaped stomach and short oral tube (about 2/3 of the manubrium); 2) its radial canals are very broad, with glandular swellings, and they enter the gastrodermal chambers of bulbs without passing through mesogloea; 3) its tentacular bulbs large, and the gastrodermal chambers of bulbs are very shallow; and 4) the epidermal parts of bulbs are high, of uniform thickness, with red ocelli (see Table 1).

Figures

FIG. 3 Sarsia macrogastera Xu, Chen, & Wang sp. nov. A and B. lateral view; C. tentacle bulbs in frontal view.; D. tentacle bulbs in lateral view.