Bunakenia hamata, Drumm & Heard, 2022

Drumm, David T. & Heard, Richard W., 2022, A new genus and species ofApseudidae, and a new species of Bunakenia (Crustacea Tanaidacea: Apseudomorpha) from the Northwest Atlantic and Gulf of Mexico, Zootaxa 5175 (1), pp. 31-54 : 44-52

Bunakenia hamata n. sp.

( Figs 10–15 )

Bunakenia sp. A sensu Heard et al., 2004 (figs. 29, 36).

Material examined. Holotype: male (♂), 5.0 mm, ( USNM 1666252 ), Georgia, USA (31°31’54.12’’N, 79°44’24’’W), depth 58 m. — Allotype: female (♀), 6.0 mm, ( USNM 1666253 ). Georgia, USA (31°31’59.88’’N, 79°44’17.88’’W), depth 57 m. Paratypes: 2 ♀♀ (~ 5.5 mm) ( USNM 1666254 ), same collection data as holotype . 1 ♂ (~ 4.5 mm); 4 ♀♀ (~ 5.5 mm); 1 juvenile (~3.0 mm), ( USNM 1666255 ), same collection data as allotype .

Diagnosis. Rostrum broadly triangular with acute tip. Eye lobes with spine, visual elements present. Pereonites 2–5 with posterolateral apophyses; all pereonites wider than long; pereonite 1 of males and non-ovigerous females with bidentate hyposphenia posterior to maxilliped insertion; hyposphenia present on all pereonites in females and pereonites 1–5 in males (genital cone on pereonite 6) and are strongly developed on all pleonites. Antennule medial margin of peduncle article 1 denticulate on much of proximal half; accessory flagellum with five articles. Cheliped basis with one spiniform seta midway on ventral margin; male cheliped with wide gap between fixed finger and base of dactylus, fixed finger with small proximal tooth; female cheliped without gape and tooth. Pereopod 1 basis lacking plumose setae and with at least two spiniform setae on ventral margin; propodus with four ventral spiniform setae. Pereopod 6 with plumose setae on dorsal margin of merus and carpus.

Etymology. The specific name hamata (Latin) is derived from the presence of hook-like processes (apophyses) on the pereonites. Gender feminine.

Description. Adult male. Holotype: ( Fig 10A ). Paratypes: ( Figs 10B , 11A – 14C ). Adult female. Paratypes: ( Figs 10C–D , 15A–C ). Body ( Fig 10A ) about 6.2 times as long as wide. Cephalothorax slightly longer than wide, longer than first two pereonites combined, about 20% of body length; with setae on lateral margin just below eyelobe; rostrum broadly triangular, anterior portion produced in acute tip; eyelobes and visual elements present, terminating distally in curved spine on ventro-lateral margin; epistome present. Pereon about 55% of body length; pereonites 1 and 2 shortest and subequal; pereonites 4 and 5 longest and subequal, slightly longer than pereonite 3 and 6; pereonites 1 and 2 have rounded lateral margins while succeeding pereonites have nearly straight margins; all pereonites wider than long, with setae on antero- and postero-lateral corners; pereonites 2–5 ( Fig 10A ) with posterolateral apophyses; bidentate hyposphenia on pereonite 1 just behind maxilliped insertion ( Fig 10B ); unidentate hyposphenia on pereonites 2–5 and genital cone on pereonite 6. Pleon as long as first two pereonites combined, about 16% of body length; pleonites expanded laterally into spiniform projection with simple setae on margins; hyposphenia present on all pleonites ( Fig 10D ). Pleotelson slightly longer than wide, more than twice as long as one pleonite, about 9% of body length; with several setae on lateral and dorsal margins, and slight lateral projection anteriorly.

Antennule ( Fig 11A ) peduncle article 1 about half as long as carapace, 2.7 times as long as wide, with several simple setae on inner margin and several simple setae and PSS on outer margin, inner margin denticulate on much of proximal half; article 2 less than half length of article 1 with several simple setae and PSS; article 3 nearly half as long as article 2 with several distal simple setae; article 4 (common article) about half as long as article 3 with one simple seta on dorsal surface. Accessory flagellum with five articles, each with at least one simple seta. Main flagellum with 12 articles with one aesthetasc on articles 4, 6, and 10.

Antenna ( Fig 11B ) peduncle with five articles; article 1 with inner distal projection denticulate and three simple setae on inner margin; article 2 longer than succeeding two articles combined, with one short simple seta on inner and outer margins; squama extending to mid-length of article 5, bearing 15 simple setae; article 3 short, with one long inner simple seta; article 4 about twice as long as article 3, with one PSS on inner margin; article 5 shorter than article 2, with one PSS and several simple setae. Flagellum with nine articles.

Labrum ( Fig 11C ) with medial depression bearing hair-like setae on either side.

Mandibles ( Fig 11D, E ). Incisor process of right mandible ( Fig 11D ) with four teeth, left mandible ( Fig 11E ) with five teeth; lacinia mobilis of left mandible with five teeth; molar process with grinding surface having welldeveloped micro-denticles; palp article one with several long simple setae, about same length as article three, article two longest, articles two and three with long simple and short pectinate setae.

Labium ( Fig 11F ) with outer margin spinulate and short setules, distal margin setulose; palp with hair-like setae on inner and outer margins and three distal spiniform setae.

Maxillule ( Fig 12A ) inner endite with five setulate setae, outer margin with hair-like setae and proximal tubercle; outer endite with ten spiniform setae and two subdistal bipectinate setae, both margins with hair-like setae; palp biarticulate with six setae increasing in length distally.

Maxilla ( Fig 12B, C ) inner lobe of fixed endite with posterior row of five bipectinate setae increasing in length laterally and with long anterior row of setae, inner distal margin serrate; outer lobe of fixed endite with one trifurcate and one bifurcate spiniform seta, several simple setae; inner lobe of moveable endite with denticulate and simple setae; outer lobe of moveable endite with two plumo-denticulate setae and several simple setae; outer distal margin serrate.

Maxilliped ( Fig 12D ) basis slightly wider than long, outer distal corner denticulate; endite with inner margin having four coupling hooks, row of ten setulate setae and several distal simple and blunt-tipped setae, outer margin with short hair-like setae; palp article 1 with outer distal corner produced and bearing one spiniform seta; article 2 with long and shorter simple setae on inner margin, outer distal corner with spiniform seta extending past the last palp article; article 3 broader than long with several simple setae on inner distal margin; article 4 short with several distal simple setae.

Epignath ( Fig 12E ) with stout, setulate spiniform seta.

Cheliped ( Fig 12F ) basis about 1.7 as long as broad, middle of ventral margin produced with a short and stout spiniform seta, and several ventrodistal simple setae; merus about 2.9 times as long as broad with several simple setae; carpus about 2.5 times as long as broad with ventral, dorsal, and dorsodistal simple setae; propodus with several simple setae on outer face of palm and dorsally, fixed finger with five ventral simple setae, cutting edge with row of spinules and row of short simple setae on outer face, short proximal tooth with two spinules; dactylus with about eight spinules on cutting edge and three simple setae on inner face, unguis about one third length of dactylus; exopodite, last article with four plumose setae.

Pereopod 1 ( Fig 13A ) coxa setose with forward-directing spine; basis almost twice as long as broad, with simple setae on ventral margin and ventrodistal corner and proximally on dorsal margin, two ventral spiniform setae; ischium wider than long with three ventrodistal simple setae; merus widest distally, about 1.7 times as long as broad, with several simple setae on ventral margin, dorsodistal corner, and a spiniform seta on ventrodistal and dorsodistal corner; carpus slightly longer than wide, with simple setae on ventral and dorsodistal margins and inner and outer surfaces, two ventral spiniform setae and one dorsodistal spiniform seta shorter than half length of propodus; propodus about same length as carpus, with simple setae on ventral, dorsal, and distal margins, four ventral spiniform setae and two dorsodistal spiniform setae, one dorsal PSS; dactylus length slightly shorter than propodus with three ventral spinules and two dorsal setae, unguis simple, slightly more than one half total length of dactylus; exopod last article with six plumose setae.

Pereopod 2 ( Fig 13B ) basis about 3 times as long as wide with several simple setae proximally and ventrodistally, spiniform seta on ventrodistal corner; ischium with several ventrodistal simple setae; merus about twice as long as wide with several simple setae on ventral and dorsodistal margins, spiniform seta on ventrodistal and dorsodistal corner; carpus almost twice as long as wide with several simple setae on ventral and dorsodistal margins, four spiniform setae (two dorsodistal, one ventrodistal, and short one on outer face); propodus slightly longer than carpus, about three times longer than wide with several ventral, dorsal, and distal simple setae, five spiniform setae (two ventral, two distal, and one dorsal), one dorsal PSS; dactylus with three minute setae, one longer dorsal seta, and one dorsodistal seta; dactylus + unguis about same length as propodus.

Pereopod 3 ( Fig 13C ) similar to pereopod 2. Basis with ventrodistal spiniform seta not observed; merus with two ventrodistal spiniform setae (one short and one long) and lacking dorsodistal spiniform seta; carpus with three ventral/ventrodistal spiniform setae and one dorsodistal spiniform seta; propodus with three ventral, one ventrodistal, one distal, and one dorsodistal spiniform seta; dactylus + unguis longer than propodus.

Pereopod 4 ( Fig 13D ) basis slightly more than 2 times as long as wide with two simple setae (one long and one short) on ventrodistal corner and two dorsal PSS; ischium with several simple seta on ventrodistal corner; merus with several simple setae on ventral margin and two ventrodistal spiniform setae; carpus about 2.5 times as long as wide with five spiniform setae on ventral and distal margins and several simple setae on ventral and distal margins; propodus slightly shorter than carpus with several distal simple setae, two spiniform setae, and four long dorsodistal pectinate spiniform setae, dorsodistally with row of short bipectinate spiniform setae, one proximal PSS on dorsal margin; dactylus naked; unguis with three small ventral teeth; unguis + dactylus shorter than propodus.

Pereopod 5 not examined (broken off on all specimens examined).

Pereopod 6 ( Fig 14A ) basis about 2.3 times as long as wide with several ventral, dorsal, and ventrodistal simple setae; ischium with four simple ventrodistal setae; merus about 1.5 times as long as wide with three plumose setae on dorsal margin, several simple setae on ventral margin and one ventrodistal spiniform seta; carpus about 2.5 times as long as wide with seven plumose setae on dorsal margin, several simple and one spiniform seta on ventral margin; propodus shorter than carpus length with several simple setae on outer surface, ventral inner surface with row of bipectinate spiniform setae and six spiniform setae, one dorsal spiniform seta, and one PSS on dorsal margin; dactylus with two minute setae; unguis + dactylus length subequal to propodus.

Pleopod ( Fig 14B ) basal article 2.4 times longer than wide with four plumose setae; exopod shorter than endopod, each ramus with 19 plumose setae.

Uropod ( Fig 14C ) length less than half body length; basal article 1.5 times as long as wide with one simple seta on distal corners; number of articles in exopod and endopod hard to discern due to multiple pseudo-articulations.

Female ( Figs 10C , 15 ) similar to male but with the following differences:

Pereon with hyposphenia on all pereonites ( Fig 10C ).

Antennule ( Fig 15A ) main flagellum with ten articles with one aesthetasc on articles 6 and 8.

Cheliped ( Figs 15B ) less robust, carpus almost 4 times as long as wide; chela without gap between fingers, fixed finger cutting edge without proximal tooth.

Pereopod 1 ( Fig 15C ) basis with three ventral spiniform setae.

Intraspecific variation. The number of plumose setae on pereopod 6 and basis of pleopods can be quite variable.

Type locality. NW Atlantic, offshore Georgia, 31.5317° N, 79.7400° W, depth 58 m.

Distribution. Florida Gulf of Mexico coast; NW Atlantic from South Florida north to South Carolina, depth 40– 200m.

Remarks. Bunakenia hamata n. sp. is known in the literature as Bunakenia sp. A ( Heard et al. 2004) and is the first record of the genus in the GOM/NW Atlantic. It can be distinguished from the other congeners by the following combination of characters: 1) pereonites 2–5 with posterolateral apophyses, 2) antennule accessory flagellum with five articles, 3) antennule inner margin of first peduncle article denticulate, 4) male cheliped with proximal tooth on fixed finger, and 5) pereopod 1 propodus with four ventral spiniform setae. Bunakenia aspalieus Bamber, Bird & Angsupanich, 2003 and Bunakenia kadazan Bamber & Sheader, 2005 are the only other species that have apophyses, but B. aspalieus has them on pereonites 3–5 and B. kadazan has them on pereonites 2 and 3. Bunakenia aspalieus also has an antennule accessory flagellum with three articles and the first peduncle article is not denticulate. Bunakenia kadazan has a 5-articulate accessory flagellum but the first peduncle article is not denticulate and the pereopod 1 propodus has five ventral spiniform setae.

Figures

FIGURE 10. Bunakenia hamata, n. sp., adult male (A, B), adult female (C, D). A, habitus (dorsal view); B, ventral view of head and pereonite 1 showing bidentate hyposphenia on pereonite 1; C, ventral view of pereon showing hyposphenia; D, ventral view of pleon showing hyposphenia. Scale bar = 1.0 mm. Photos by D. Drumm.

FIGURE 11. Bunakenia hamata, n. sp., adult male. A, antennule (dorsal view); B, antenna (dorsal view); C, labrum; D, right mandible; E, left mandible; F, labium. Scale bars: A–B = 0.2 mm; C–F = 0.1 mm.

FIGURE 12. Bunakenia hamata, n. sp., adult male. A, maxillule; B, maxilla (moveable endite); C, maxilla (fixed endite); D, maxilliped; E, epignath spine; F, cheliped (outer view). Scale bars: A–E = 0.1 mm; F = 0.2 mm.

FIGURE 13. Bunakenia hamata, n. sp., adult male. A, pereopod 1 (outer view); B, pereopod 2 (inner view); C, pereopod 3 (outer view); D, pereopod 4 (inner view). Scale bars = 0.2 mm.

FIGURE 14. Bunakenia hamata, n. sp., adult male. A, pereopod 6 (inner view); B, pleopod; C, uropod. Scale bars = 0.2 mm.

FIGURE 15. Bunakenia hamata, n. sp., adult female.A, antennule (dorsal view); B, cheliped (outer view); C, pereopod 1 (inner view). Scale bars = 0.2 mm.