Monstrotanais ingens Wiak & Błażewicz-Paszkowycz, 2007, n. sp.

• Main Authors: Wiak, Piotr Jó Ż, Błażewicz-Paszkowycz, Magdalena
• Format: Text
• Language: unknown
• Published: Zenodo 2007
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Malacostraca; Tanaidacea; Monstrotanais; Monstrotanais ingens; Antarctic; Pacific; Seta; George V Coast; Antarc*
• Online Access: https://dx.doi.org/10.5281/zenodo.6241018; https://zenodo.org/record/6241018

Monstrotanais ingens n. sp. (Figs 1–3) Diagnosis: Pereonites 2 and 5 square. Pleotelson little longer than wide. Uropods inserted in proximal half of pleotelson. Pereopods 2–6 carpus with seta reaching beyond half of propodus. Pereopods 4–6 dactylus and unguis fused, with sharp spine at the fusion point. Material examined: Holotype female (dissected on slides), USNM 1100227, Eltanin Cr 38 Sta 7 / 5, 150 °06.40'E – 64 ° 13.30 'S, depth 3543 m, 30 Mar 1969. Etymology: ingens [Lat.] = great, vast, huge. The name reflects the comparatively large size of the species and unusual structure of its chelae. Description: Female without oostegites (Figs 1 A, E-F), 4.8 mm long. Body about ten times as long as wide. Carapace (Fig. 1 B) 17 % of body length, narrow, 1.7 times as long as wide, lateral edges parallel, tapering frontally; pereonite 1 0.8 times as long as wide, pereonite- 2 subequal to pereonites 4 and 5; pereonites 2, 4 and 5 about as long as wide; pereonite- 3 longest, 0.73 times as long as carapace; pleon as long as combined length of pereonites 4 and 5 plus half of pereonite- 3; pleotelson as long as wide, rounded distally. Antennule (Fig. 2 A): 0.75 times as long as carapace; article- 1 subequal to combined length of remaining articles, about three times as long as wide, with five bipinnate setae and one simple seta subdistally; article- 2 as long as article- 4, with five bipinnate setae and two simple setae distally; article- 3 shortest, 0.7 times as long as article- 2, with one simple seta in middle and one simple seta distally; article- 4 narrow, with three long and four short, simple setae terminally. Antenna (Fig. 2 B): Article- 1 short; article- 2 short, about as long as article- 3,with microtrichia; article- 3 with long simple seta subdistally; article- 4 with fusion line, longest, six times as long as wide, twice as long as article- 5, with one bipinnate seta in middle, six bipinnate and three simple setae distally; article- 5 narrow, almost six times as long as wide, with one simple seta distally; article- 6 very short, as long as wide, with five long, terminal setae. Mouth parts: Labrum (Fig. 2 C) hood-shaped, covered by numerous minute setae. Mandible (Fig. 2 D): molar process well developed, as long as incisor, bent down, with eight subacute spines and three tubercles distally; lacinia mobilis well developed, crenulated. Maxillule (Fig. 2 E) with seven spiniform and three serrated setae distally, outer margin with three simple setae subdistally; palp (Fig. 2 E’) with fusion line and two long setae terminally. Maxilla (Fig. 2 F) semitriangular, naked. Labium (Fig. 2 G) 2 -lobed, narrow, with numerous minute setae on distal margin of inner lobe. Maxilliped (Fig. 2 H): bases fused, little as long as wide, without seta; endite with two short setae and one well developed tubercle distally; palp article- 1 with microtrichia; article- 2 with three setulated setae on inner margin and one simple seta on outer margin; article- 3 with two long and two short simple setae on inner margin; article- 4 slender, with three long simple setae and one setulated seta on inner margin and small outer seta. Cheliped (Fig. 2 I): Basis narrowing proximally, distally twice as wide as in proximal part; merus well developed, with one ventral seta; carpus 1.3 times as long as broad, with blunt tooth distally, one short, simple seta dorsally and two simple setae ventrally; propodus and fixed finger much as long as carpus, propodus with wide ventral flange and with strongly serrated ventral margin and two simple setae ventrally; fixed finger with strong claw and strongly calcified inner margin, with three simple setae near dactylus insertion; dactylus with small seta proximally and with serrated dorsal margin, inner margin with one well calcified tubercle; unguis strongly calcified, subequal in length to dactylus. Pereopod- 1 (Fig. 3 A): Of walking type; coxa with one simple seta; basis subequal to ischium, merus and carpus combined, about twice as long as wide; merus as long as carpus, with one setulated seta and one simple seta distally; carpus with one setulated, one spiniform and three simple, short setae distally; propodus 1.4 times as long as carpus, with one setulated and one spiniform seta ventrally, one simple seta dorsally and one simple seta distally that reaches unguis, ventral margin covered by numerous microtrichia; dactylus 0.3 times as long as propodus, unguis 0.5 times as long as propodus, dactylus and unguis combined subequal to propodus. Pereopod- 2 (Fig. 3 B): Of walking type; coxa with one simple seta; basis massive, as long as ischium, merus and carpus combined, about twice as long as wide, basis ventral margin with row of microtrichia; ischium with one simple seta ventrally; merus as long as carpus, with one simple and one strong, setulated seta distally; carpus 1.3 times as long as wide, with three distal, setulated setae (two short and one long), carpus with microtrichia; propodus 1.25 times as long as carpus, 2.5 times as long as wide, with one setulated seta ventrally, ventral margin with microtrichia; dactylus about 0.5 times as long as propodus, with one simple seta reaching unguis; unguis little as long as dactylus, dactylus and unguis combined as long as propodus. Pereopod- 3 (Fig. 3 C): Similar to pereopod- 2. Pereopod- 4 (Fig. 3 D): Of walking type; coxa with microtrichia; basis as long as ischium, merus and carpus combined, 1.75 times as long as wide, naked; ischium with two simple setae; merus little shorter than carpus, with two setulated setae subdistally; merus, carpus and propodus with microtrichia; carpus subequal to propodus, with three setulated (two short and one long) and one simple setae distally; propodus 2.2 times as long as wide, with one long and two short, setulated setae distally; dactylus and unguis fused, with numerous minute setae ventrally and one spine at fusion line (Fig. 3 F’), dactylus and unguis combined little shorter than propodus. Pereopod- 5 (Fig. 3 E): Similar to pereopod- 4. Pereopod- 6 (Fig. 3 F): Similar to pereopod- 5, but propodus with three setulated and two simple setae distally. Pleopods 1–5 (Fig. 3 G): Basal article naked. Exopod with nine setae distally and one seta proximally separated by large gap from the others; endopod with five setae on outer margin and one subdistal seta on inner margin. Uropod (Fig. 3 H): Endopod 2 -articled; article- 1 subequal to article- 2, with one bipinnate seta distally; article- 2 with four long setae terminally. Exopod 1 -articled, subequal to endopod proximal article, exopod with two short setae in middle and one short and one long seta terminally. Distribution: Species know only from type locality: East Antarctic – out off George V Coast/Adelie Coast; depth 3543 m. Remarks: At the moment genus Monstrotanais includes two species. One of them, Monstrotanais mirabilicheles, was found at foot of an underwater mountain in North–Eastern Pacific. Monstrotanais ingens n. sp can be distinguished from M. mirabilicheles by having pereonite- 5 as long as wide, a long pleotelson covering the uropods from the dorsal side and the long article- 4 of antenna that is twice as long as article- 3. : Published as part of Wiak, Piotr Jó Ż & Błażewicz-Paszkowycz, Magdalena, 2007, New records of two rare genera, Monstrotanais Kudinova-Pasternak, 1981 and Robustochelia Kudinova-Pasternak, 1983 (Tanaidacea: Crustacea), pp. 19-35 in Zootaxa 1505 on pages 21-25, DOI: 10.5281/zenodo.177166