Oahutanais makalii, Morales-Núñez & Larsen & Cooke, 2016

Morales-Nunez, Andres G., Larsen, Kim & Cooke, William J., 2016, Oahutanais makalii, a new genus and species of colletteid tanaidacean (Crustacea, Peracarida) from shelf-waters off Hawaii, with a taxonomic key, Zoosystematics and Evolution 92 (1), pp. 1-12 : 3-8

publication ID	https://dx.doi.org/10.3897/zse.92.5581
publication LSID	lsid:zoobank.org:pub:F8F8D8A7-BBD5-4A58-81EC-48DA1B09A88B
persistent identifier	https://treatment.plazi.org/id/934BF56A-4CE7-40FE-B1DC-1F93E8EDD24B
taxon LSID	lsid:zoobank.org:act:934BF56A-4CE7-40FE-B1DC-1F93E8EDD24B
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Oahutanais makalii
status	sp. n.

Treatment

Oahutanais makalii sp. n. Figures 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6 , 7 View Figure 7 , 8 View Figure 8

Type material.

Holotype Adult ♀, length 0.9 mm, (USMN 1283305), BPOBS Station (Stn) HB4-R1 (21° 16 ’47.7’’ N - 158° 01 ’38.1’’ W), depth 62 m, substrata: "predominantly fine and medium sand", coll. by City and County of Honolulu Oceanographic Team, March 2013.

Paratypes. Four ♀♀ (USMN 1283306); four ♀♀ ( GCRL 06534); and six ♀♀ ( BPBM 2015.097; four on SEM stubs and two in alcohol), SIOBS Stn D3A (21° 16 ’55.3’’ N - 157° 53 ’49.9’’ W), depth 49 m, substrata "primarily coarse sediment including shell fragments", coll. by City and County of Honolulu Oceanographic Team, October 2014. Additional specimens from the type locality are in the collection of the authors.

Other material examined.

Thirteen ♀♀, one ovigerous ♀, two ♀♀ with remains of marsupium, SIOBS Stn D 3A (21° 16 ’55.3’ N - 157° 53 ’49.9’ W), depth 49 m, substrata "primarily coarse sediment including shell fragments", coll. by City and County of Honolulu Oceanographic Team, October 2014 ; 27 specimens (spec), MOBS Stn D (21° 25' 32.3"N - 157° 42' 53.6"W), depth 30 m, October 2013; two spec, SIOBS Stn C1A (21° 17' 38.3"N - 157° 55' 28.3"W), depth 19.2 m, October 2014; one spec, SIOBS Stn C5A (21° 16' 53.9"N - 157° 51' 25.4"W), depth 20.1 m, October 2014; two spec, SIOBS Stn D1 (21° 17' 23.2"N - 157° 55' 29.8"W), depth 49.1 m, October 2014; three spec, SIOBS Stn D2 (21° 16' 55.2"N - 157° 54' 36.3"W), depth 56.4 m, October 2014; 40 spec, SIOBS Stn D3A (21° 16' 55.9"N - 157° 53' 48.8"W), depth 50 m, October 2014; 16 spec, SIOBS Stn D5 (21° 16' 36.8"N - 157° 51' 33.9"W) depth 52.1 m, October 2014; eight spec, SIOBS - Stn D6 (21° 16' 02.5"N - 157° 50' 46.4"W) depth 50.0 m, October 2014; two spec, SIOBS Stn E1 (21° 17' 09.5"N - 157° 55' 32.2"W), depth 102.4 m, October 2014; 49 spec, SIOBS Stn E3 (21° 16' 42.9"N - 157° 53' 49.5"W), depth 84.4 m, October 2014; three spec, SIOBS Stn E5 (21° 16' 22.5"N - 157° 51' 40.3"W) 101.5 m, October 2014; four spec, SIOBS Stn E6 (21° 15' 51.1"N - 157° 50' 57.2"W) depth 102.4 m, October 2014; 7 spec, WOBS Stn Z (21° 25' 38.8"N - 158° 11' 48.1"W) depth 29.3 m, October 2014.

Diagnosis.

As the generic diagnosis above.

Etymology.

The species name, makali’i, is Hawaiian for tiny or minute and reflects both where the material used in this study was collected and its small size relative to other tanaidaceans within this benthic community.

Type locality.

Off Barbers Point Oahu, BPOBS study area (21° 16 ’47.7’’ N - 158° 01 ’38.1’’ W), Hawaii, May 2013.

Description.

Based in holotype female, length 0.9 mm (USMN 1283305).).

Body (Fig. 2 View Figure 2 ) length about 0.9 mm, about 8.6 times width.

Cephalothorax (Figs 2 View Figure 2 , 6A-B View Figure 6 ) about 15% of TL, slightly longer than first two pereonites combined, about 1.5 times longer than wide, oval shape (Fig. 6B View Figure 6 ); with distolateral seta. Eye-lobes absent.

Pereon (Fig. 2 View Figure 2 ): about 60% of TL; pereonites 1-3 and 6 sub-rectangular, wider than long; pereonites 4-5 quadrate.

Pleon (Figs 2 View Figure 2 , 7A View Figure 7 ): about 20% of TL; combined length of pleonites 1 to 5 slightly shorter to that of pereonites 5 and 6 combined; all pleonites subequal, much wider than long; pereonite-1 with two simple setae distally.

Pleotelson (Figs 2 View Figure 2 , 5B View Figure 5 ) about 5% of TL, same length of pleonites 5 and 6 combined; sub-rectangular, with two broom setae and two simple setae, apex blunt; pleonite-5 with two simple setae distally.

Antennule (Figs 3A View Figure 3 , 6A-B View Figure 6 ): slightly longer than 2/3 length of cephalothorax. Article-1 about 3.1 times long than wide, longer than distal three articles, with three setulose setae and one simple seta along lateral margin. Article-2 about 1.1 times longer than wide, with distodorsal simple seta; with two setulose setae and one long (longer than articles 2 to 4 combined) simple seta on distoventral margin. Article-3 about 1.5 times wider than long, with two simple setae dorsally and one simple seta lateral. Article-4 about 1.4 times longer than wide, with four simple setae of different length. Terminal segment minute and covered by article-4, with one seta and one aesthetasc (only visible with SEM images) (Fig. 6B View Figure 6 ).

Antenna (Figs 3B View Figure 3 , 6B View Figure 6 ): article-1 short, asetose. Article-2 about 1.2 times wider than long, with distolateral short seta. Article-3 about 1.3 times wider than long, with distodorsal long simple seta. Article-4 about 3.0 times longer than wide, longer than articles 2 and 3 combined, with one setulose seta and two simple setae on distoventral setae margin. Article-5 about 2.0 times longer than wide, with one simple seta on distolateral margin. Article-6 minute, with five simple setae of unequal length.

Mouthparts: Labrum (Figs 3C View Figure 3 , 7A View Figure 7 ): hood-shaped and finely setose. Mandibles (Fig. 3D-E View Figure 3 ): left mandible, incisor with two to three uneven denticles; lacinia mobilis narrow, apparently smooth (Fig. 3D View Figure 3 ). Right mandible incisor with broad and crenulate upper margin (Fig. 3E View Figure 3 ). Molar process pointed, with small distoventral spines (Fig. 3D-E View Figure 3 ). Labium (Figs 3F View Figure 3 , 6B View Figure 6 , 7A View Figure 7 ): bilobed with distolateral processes. Maxillule (Figs 3G View Figure 3 , 6B View Figure 6 , 7A View Figure 7 ): endite with seven distal spiniform setae (two bifid), two sub-distal simple setae, and cluster of setules on distal margin; palp bearing two long terminal setae of unequal length. Maxilla: not recovered.

Maxilliped (Figs 3H View Figure 3 , 7A View Figure 7 ): basis fused, apparently asetose. Endites unfused, with one simple seta and medial small process, outer margin with small spine. Palp: Article-1 asetose. Article-2 with setulose seta on outer margin, inner sub-distal margin with two simple setae and geniculate, finely-pectinate spiniform seta (serrations visible at magnification 100x). Article-3 with two setulose setae on inner margin. Article-4 with subdistal setulose setae and cluster of setules on outer margin (Fig. 7A View Figure 7 ), inner and distal margin with five setulose setae.

Epignath: not recovered.

Cheliped: (Figs 4A-B View Figure 4 , 6A-C View Figure 6 , 8 View Figure 8 ): cheliped attached just anterior to the posterior margin of cephalothorax and very close to the midventral line, via sclerite (Figs 6B-C View Figure 6 , 8 View Figure 8 ). Basis about 1.9 times longer than wide, with subdistal short seta. Merus triangular, with simple seta on ventral margin. Carpus about 1.8 times longer than wide, anterior margin with distodorsal seta; ventral margin with two simple setae of different length. Propodus about 1.4 times longer than wide, with small simple seta near insertion of dactylus. Fixed finger with crenulated ventral margin, with two ventral setae and three simple setae on outer incisive margin, with two to three sharp denticles on inner margin. Inner surface (Fig. 4B View Figure 4 ) with three short simple setae (one distinctly longest) at articulation with dactylus. Dactylus with long simple proximal seta on inner side.

Pereopod-1 (Figs 5A View Figure 5 , 8 View Figure 8 ): attached ventrally, coxa with simple seta on anterodistal margin. Basis about 4.0 times longer than wide, asetose. Ischium wider than long, with simple seta shorter than merus. Merus about 1.5 times longer than wide, with two distoventral pectinate setae (Fig. 5H View Figure 5 ) (one short and one robust, just longer than carpus). Carpus about 1.7 times longer than wide; two pectinate distodorsal setae and one robust pectinate distoventral seta (Fig. 5D View Figure 5 ). Propodus about 3.1 times longer than wide; distodorsal margin with spine-like apophysis; distoventral margin with one pectinate subdistal seta. Dactylus elongate, together with unguis longer than propodus, dactylus shorter than unguis.

Pereopod-2 (Fig. 5B View Figure 5 ): similar to pereopod-1, except basis and propodus longer. Propodus with ventrodistal pectinate small seta. Dactylus and unguis shorter than propodus.

Pereopod- 3 (Fig. 5C View Figure 5 ): similar in form to pereopod-2, except shorter than other five pereopods.

Pereopod-4 (Figs 5D View Figure 5 , 8 View Figure 8 ): attached ventrally, basis about 4.0 times longer than wide, with setulose seta on proximal dorsal margin. Ischium wider than long with two simple setae of unequal length on posterior margin, long seta shorter than merus. Merus about 2.0 times longer than wide, with two distoventral pectinate setae. Carpus about 2.0 times longer than wide, with four pectinate setae of unequal length. Propodus about 3.5 times longer than wide; distodorsal margin with long pectinate setae, reaching beyond the dactylus; distoventral margin with two pectinate setae. Dactylus and unguis longer than propodus, dactylus shorter than unguis.

Pereopod-5 (Fig. 5E View Figure 5 ): Similar to pereopod-4, except carpus and dactylus longer. Basis with setulose seta on mid-ventral margin.

Pereopod- 6 (Fig. 5F View Figure 5 ): similar to pereopod-5, except basis, carpus, and propodus slightly longer; ischium, merus, and dactylus shorter.

Pleopods: Absent. (Fig. 7B View Figure 7 )

Uropod (Figs 5G View Figure 5 , 7B View Figure 7 ): biramous, twice as long as pleotelson, but half as long as entire pleon. Basal article shorter than pleotelson, without distal apophyses. Exopod uni-articulate, slightly longer than endopod article-1, with simple seta on mid-lateral? margin, and two simple distal setae (one longer). Endopod biarticulate, article-1 with three setae (two setulose and one simple) on subdistal inner margin; article-2 with subdistal simple lateral seta, with one setulose and five (four long and one short) simple setae distally.

Male. Unknown.

Ovigerous female. As above. When embryos were present, six (smaller embryos) was the most observed; typically only three or fewer were present.

Remarks.

Among the family Colletteidae , Oahutanais makalii sp. n. shows some similarities with Cetiopyge mira Larsen and Heard, 2002, Isopodidus janum Larsen and Heard, 2002, and Collettea minima Hansen, 1913 (see Larsen 2000) in having the unusual presence of bifurcate spiniform terminal setae on the maxillule endite; however, the presence of this kind of setae has also been reported in some species of other families such as the Tanaellidae Larsen & Wilson, 2002 ( Arthrura andriashevi Kudinova-Pasternak, 1966), Cryptocopidae Sieg, 1977 ( Curtichelia expressa Kudinova-Pasternak, 1987), and Paratanaoidea incertae sedis ( Parafilitanais mexicanus Larsen, 2002). Larsen and Heard (2002) suggested that this setal character could have a wider occurrence in the deep-sea species, since it has only been reported in specimens collected in deep waters. Our results indicated that the presence of these unusual setae is not restricted to deep-sea Tanaidacea, since Oahutanais makalii was found in shallow waters (<105 m).