“Lionectes humicephalotus, new species
Holotype. Brooding female, bl 1.2 mm, all limbs on right side except pereopod I intact, USNM 227056.
Paratypes. Three brooding females, all bl 1.2 mm, partially or completely dissected for description, SIO.
Type-Locality. Institute of Oceanography, Dalhousie (I0Dal) benthic station 13, North of King George Island, South Shetland Islands, 61°18'S, 58°00'W, 282 m, collected with a small epibenthic sled on 7 February 1970 during Bedford Institute of Oceanography cruise Hudson 70.
Other Material. Female, IODal 7; damaged female, 69Rankin 001AD; damaged brooding female, 68Rankin 0055SBT. SIO.
General Distribution. South Shetland Islands to the Weddell Sea, 58.6-659 m. Derivation of Name. Humicephalotus means "provided with flat head."
Diagnosis. See description. There is insufficient information on the species of this genus to allow a diagnosis at this time.
Description of Brooding Females Only. Body Characters (Fig. 14A-B): Adult body length 1.1-1.4 (4 inds) mm, length 1.9-2.0 (4 inds) width.
Body setation: Natasome with approximately 5 setae on each ventrolateral margin; other dorsal surfaces with scattered fine setae.
Cephalon: Dorsal length 0.35 width, length 0.68 height, width 0.67-0.70 (2 inds) width of body at pereonite 5. Ventral margin at posterior articulation of mandible lacking indentation or notch.
Antennula: Length 0.16 body length, with 7 articles and 2 aesthetascs distally. Article 1 medial length 0.94 width; medial lobe with approximately 3-4 broom setae. Article 2 with broom setae. Article 2 with 2 distal projections bearing broom setae: 1 dorsally and 1 laterally. Article 2 length (including dorsal projection) 0.58 article 1 medial-lobe length. Article 3 length 0.34 article 2 length.
Antenna: Total length greater than 1.6 (2 inds) body length (tip of flagellum broken). Article 5 shorter and more robust than article 6; article 5 length 0.58 article 6 length, 0.23 body length.
Mandible: Left mandible with 3 cusps on incisor process; right mandible with large central cusp, smaller cusp on either side, and 3 small denticles on dorsal margin. Lacinia mobilis only slightly narrower than left incisor process, with 3 cusps extending to tip of incisor process. Spine row reduced, with 3 members. Molar process with thin cuticle, not calcified, distal end with no circumgnathal denticles or large pointed cusp on ventral margin; posterior margin with 1 flattened setulate seta; triturating surface without evident sensory pores. Condyle length 0.35 (2 inds) mandibular body length. Palp second article length 0.36-0.38 (2 inds) mandibular body length; distal article robust, strongly curled.
Maxillula: Normally developed. Inner endite short and rounded, lacking large apical seta, but with several smaller setae, width 0.61 outer endite width.
Maxilla: Normally developed. Outer lobes approximately same length as inner lobe.
Maxilliped: Basis with 2 receptaculi and 3 fan setae distally. Endite length 0.52 total basis length. Palp article 2 width 1.9 endite width, lateral length 2.0 medial length. Palp article 3 lateral length 0.34 medial length. Epipod oval, lateral edge scalloped; length 0.88 basis length; length 1.5 width. Coxa elongate, subequal to basal section of basis.
Ambulatory Pereopods: Pereopods I-IV thin, lightly setose; length-body length ratios 0.61, 0.92, 1.0, 1.2. Bases I-IV length-body length ratios 0.17, 0.15, 0.17, 0.21.
Natatory Pereopods: Natapods heterogeneous in form: pereopod V with very broad carpus and propodus, many natatory setae, and rudimentary dactylus; pereopod VI with narrower carpus and propodus, many natatory setae, and long curved dactylus; pereopod VII resembling walking leg with narrow distal segments, approximately 4 natatory setae on ventral margin of carpus only, propodus longer than carpus. Pereopods V-VII increasing in length but becoming narrower posteriorly; length-body length ratios 0.74, 0.79, 0.83. Bases V-VII also increasing in length posteriorly; length-body length ratios 0.17, 0.21, 0.23. Carpi V-VII length-width ratios 1.0, 1.4, 3.7. Propodi V-VII length-width ratios 1.5, 2.5, 6.6; propodi V-VII length carpus length ratios 0.90, 0.84, 1.5. Dactyli VI-VII long, curved; length-propodus length ratios 0.90, 0.89. Dactylus V rudimentary.
Male Pleopods I and II: unknown.
Female Pleopod II: Keel narrow, rounded in lateral view, without distinct apex or large setae, deepest in proximal half of pleopod, distinctly set off from lateral fields. Ventral surface with only fine setae. Distolateral margins with approximately 10-12 long plumose setae on distal half of margins. Length 1.3 width; depth 0.36 length.
Pleopod III: Exopod distally truncate, longer than endopod, with 3 long plumose setae, and 1 simple seta on distal tip. Endopod with 3 distal plumose setae.
Uropod: Protopod length 1.4 width; length 0.08 body length. Exopod 0.54 endopod length. Endopod 0.68 protopod length. Distal margin of protopod with approximately 6 whip setae.
Remarks. Lionectes humicephalotus is currently known only from females; 4 brooding females were collected at the type locality off King George Island, and the other two localities yielded only damaged females. L. sp. incertae sedis (Vanhoffen, 1914) is also known from a single female. There are differences between the illustrations of L. sp. incertae sedis and L. humicephatotus described here, but it is uncertain whether the illustrations of the former species are accurate in small details. These include the lateral margin of pereonite 7 extending to the body margin, the longer uropodal exopod, and the presence of an elongate dactyl on pereopod VII. Other differences might be developmental because Vanhoffen's specimen was not brooding. A more detailed characterization of Lionectes must await the capture of males.”
(Wilson, 1989: 47-52)
