Pseudosympodomma adensis, Mühlenhardt-Siegel, Ute, 2008

Mühlenhardt-Siegel, Ute, 2008, The Cumacea of the Red Sea and Gulf of Aden, with the description of four new species and one genus, Zootaxa 1828, pp. 1-17 : 5-10

Pseudosympodomma adensis sp. nov.

( Figs 3–5 )

Pseudosympodomma sp., Mühlenhardt-Siegel, 1996: pp. 115–117, fig. 4.

Type material. Holotype: adult male, ZMH: K 41944 ; 16 March 1987; type locality: inner Gulf of Aden, 12°30.9'N 44°47.7'E, 76 m depth, RV Meteor cruise 5/2, station number 283, Kurre; M. Türkay coll.

Paratypes: 12 females, 5 males, same data as holotype. Station number 236, Kurre and KD, 35–45 m depth: 2 females.

Etymology: The new species is named after the type locality, the Gulf of Aden.

Diagnosis. Dorsomedian carina of carapace with three teeth in females, subadult males with teeth 2 and 3 behind the frontal lobe area, no teeth in adult males; dorsomedian carina on pedigerous somites, paired on somites 3 to 5. Basal article of the uropod endopod longer than distal article.

Description. Holotype adult male ( Fig. 3 ), 10.5 mm total length, carapace 0.2 times total length, smooth; pseudorostral lobes do not meet in front of ocular lobe; siphonal tube short; ocular lobe elongate; eye present but without pigmented lenses.

Antennal notch shallow; anterolateral tooth not prominent; anteroventral margin of carapace smooth; integument well calcified, weakly granulate.

Five free thoracic segments visible, the first very short, fourth somite with lateral process directed forward. Dorsomedian carina on pedigerous somites 2 to 4. Pleon 1.5 times longer than carapace and free thoracic somites combined, tergites overlapping; telsonic segment almost rectangular, 1.2 times longer than wide.

Appendages: paratype male.

Antenna 1 ( Fig. 5 , A1): similar to female, see Pseudosympodomma sp. ( Mühlenhardt-Siegel 1996). Accessory flagellum three articulate, the third article very tiny; half as long as basal article of main flagellum. Main flagellum two articulate, brush of very thin aesthetascs from basal article of main flagellum.

Antenna 2 ( Fig. 5 , A2): with long flagellum reaching beyond first pleon segment; peduncle articles 4 and 5 with hair-like setae.

Mandible ( Fig. 5 , Md): with four teeth on pars incisiva; 18 serrulate setae (17 on left mandible, here short lacinia mobilis) between pars incisiva and pars molaris.

Maxillla 1 (maxillula,) ( Fig. 4 , Mx 1): outer endite with eight stout setae, single pappose seta on outer margin; inner endite with five slightly curved simple setae; margins with hair-like setae.

Maxilla 2 (maxilla) ( Fig. 4 , Mx 2): distal margin with at least 10 stout serrulate setae hidden in rows of long simple setae; inner margin with pappose setae.

Maxilliped 1 ( Fig. 4 , Mxp1): B/R ratio 1.1, RLA: 0/36/24/24/16; basis with six simple setae along inner margin, endite with two retinacula and two hand-like setae; ischium missing, merus as wide as basis, almost triangular; carpus as wide as merus and basis, with eight bicuspidate setae along inner margin, each between hair-like setae; propodus small and slender, long pappose setae on outer distal margin; dactylus very small, strong terminal seta as long as dactylus.

Maxilliped 2 ( Fig. 4 , Mxp2): B/R ratio 1.2, RLA: 9/26/ 33/22/10; basis with two relatively long plumose setae at inner distal corner; carpus with eight plumose setae along inner margin and one at outer distal corner; propodus with six forked setae on distal inner margin and one plumose seta on distal outer corner; dactylus longer than terminal seta (unguis).

Maxilliped 3 ( Fig. 5 , Mxp3): basis broken during dissection, RLA: 19/23/23/22/13; basis with distal prolongation inner margin serrate and with five short and distally two long pappose setae, prolongation reaching merus-carpus articulation; merus with three teeth on outer margin, carpus with four teeth on inner margin; exopod present, not drawn.

Pereiopod 1 ( Fig. 5 , P1): broken after basis; basis with three setae on proximal quarter and one on distal margin; exopod present.

Pereiopod 2 ( Fig. 5 , P2): B/R ratio 0.7, RLA: 4/20/23 /9/44; merus with one long and two shorter stout setae, carpus with two long and two short stout setae on distal margin; terminal seta 0.9 times as long as basal part of dactylus; exopod present.

Pereiopod 3 ( Fig. 5 , P3): B/R ratio 0.8, RLA: 14/25/ 37/15/9; carpus with eight small teeth along outer margin.

Pereiopod 4 ( Fig. 5 , P4): B/R ratio 0.6, RLA: 13/27/ 39/14/7; carpus with 10 teeth along outer proximal margin.

Pereiopod 5 ( Fig. 5 , P5): basis broken during dissection, RLA: 9/24/41 /16/10.

Uropod peduncle 2.1 times longer than pleonite 6 and 1.5 times longer than uropod endopod, peduncle with numerous more or less long, strong simple setae along proximal inner margin, and 11 to 14 long and acute setae along distal inner margin. Exopods broken, endopod two articulate, basal article 1.2 times longer than distal article. Distal article with eight thin setae along inner margin, two strong (broken) terminal setae and five strong, short setae along outer margin ( Fig. 5 , U).

Female: appendages as described in Mühlenhardt-Siegel (1996). The dorsomedian teeth and the dorsomedian carina of the pedigerous segments prominent in females and subadult males (adult males do not have teeth and the carina is much less prominent on the carapace and the pedigerous somites). Dorsomedian carina narrowly paired on hind part of carapace (the furrow getting more indistinct in older females) and paired on pereionite 3 to 5, becoming gradually shallower and separate in hind part.

Subadult males resemble females in terms of carina.

Remarks. The new species resembles P. carinatum Corbera & Martin, 2002 from shallow waters off Thailand in terms of female habitus and the middorsal carina with the dorsal teeth not restricted to the frontal lobe area. It differs from P. carinatum in having the basal article of the uropod endopod longer than the distal article. It differs from its congeners P. africanum Stebbing, 1912 and P. hoinicae Petrescu, 1998 , which also have a basal article longer than the distal article, in the following characters: P. adensis sp. nov. has the middorsal teeth 2 and 3 behind the frontal lobe area, whereas both other known species have the dorsomedian teeth of the carapace in the frontal lobe region; P. a d e n s i s sp. nov. has a serrate inner part of the distal prolongation of the basis of maxilliped 3 whereas P. hoinicae has no serration; and P. adensis sp. nov. has three setae on the basis of pereiopod 1, which are lacking in P. a f r i c a n u m.

Figures

FIGURE 3. Pseodosympodomma adensis sp. nov., paratype female (a) and holotype male (b), habitus; scale bar: 1 mm.

FIGURE 4. Pseodosympodomma adensis sp. nov., paratype male, mouthparts. Scale bar: 0.1 mm, if not otherwise indicated: Mx 1: maxillula; Mx 2: maxilla; Mxp 1: maxilliped 1; Mxp 2: maxilliped 2.

FIGURE 5. Pseodosympodomma adensis sp. nov., paratype male, appendages, scale bars: 0.1 mm. Scale a: A 2: antenna 2; Mxp 3: maxilliped 3; P 1: pereiopod 1 basis; P 2: pereiopod 2; P 3: pereiopod 3; P 4: pereiopod 4; P 5: pereiopod 5; U: pleonite 6 and uropods. Scale b: A 1: antenna 1; Md: mandible.