Holophryxus richardi Koehler 1911

• Main Authors: Huys, Rony, Savchenko, Alexandra S., Kosobokova, Ksenia N.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2023
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Malacostraca; Isopoda; Dajidae; Holophryxus; Holophryxus richardi; Johannessen; Arctic; North Atlantic
• Online Access: https://zenodo.org/record/8011047; https://doi.org/10.5281/zenodo.8011047

HOLOPHRYXUS RICHARDI KOEHLER, 1911 Synonym: Holophryxus sp. (Ho. Richardi Koehler 1911) sensu Stephensen (1912). Original description: Koehler (1911 —as Ho. Richardi): 23–25, figs 15–17 (immature ♀). Additional descriptions: Stephensen (1912): 108– 109, figs 9–10 (subadult ♀). Stephensen [1912 —as Holophryxus sp. (Ho. Richardi Koehler?)]: 109–112, figs 11–12, 13 (bottom), 14 (adult ♀). Stephensen (1915): 24 (adult ♀). Rustad (1935): 9–30, figs 1–18 (subadult and adult ♀♀ and ♂). Host: Eusergestes arcticus (Dendrobranchiata, Sergestidae). Distribution: North Atlantic Ocean (Table 2). Differential diagnosis: Holophryxus. Body length 3.7 mm (immature ♀; N = 1) (Koehler, 1911); 9 mm (subadult ♀; N = 1), 14 mm (adult ♀; N = 1) (Stephensen, 1912); 8 mm (adult ♀) (Stephensen, 1915); 4.1–12.9 mm (immature ♀♀; N = 6), 11.2–16.5 mm (adult ♀♀; N = 11), 1.64–2.00 mm (♂♂; N = 3) (Rustad, 1935); 8.6–16.4 mm (adult ♀♀; N = 4) (Greve & Johannessen, 1981); 6.55–13.86 mm (adult ♀♀; N = 23), 9.66–12.18 mm (ovigerous ♀♀; N = 2) (Jones & Smaldon, 1986). Colour of ♀ pale yellow in alcohol (Stephensen, 1912), from yellow to red in live specimens (Rustad, 1935; Greve & Johannessen, 1981); unknown in ♂. FEMALE: Body spindle shaped, about 2.0 times as long as maximum width. Cephalon demarcated from pereon in dorsal aspect by constriction bilaterally and transverse surface fold dorsally; dorsal prominence with emarginate (bilobed) anterior margin; only small part of ventral cephalic ridge discernible in dorsal aspect, slightly arched, about 0.45 times as long as maximum width, anterior margin rounded, without paired pit organs; posterolateral corners of cephalic ridge with pointed processes, representing coxal plates of incorporated first pereonite. Maxilliped present, bilobate. Median sternal plate with paired posteriorly directed appendices. Pereon with five pairs of incubatory plates; oostegite 1 slightly bilobate, with medial projection on proximal lobe; oostegite 5 unilobate, covering about 60–65% of ventral side of body, ...