Haplomesus franklinae, Merrin & Poore, 2003

Merrin, K. L. & Poore, G. C. B., 2003, Four new species of Ischnomesidae (Crustacea: Isopoda: Asellota) from off south-eastern Australia, Memoirs of Museum Victoria 60 (2), pp. 285-307 : 286-289

publication ID	https://doi.org/ 10.24199/j.mmv.2003.60.27
persistent identifier	https://treatment.plazi.org/id/671587C8-307D-551E-FF3E-70ACFC6EC662
treatment provided by	Felipe
scientific name	Haplomesus franklinae
status	sp. nov.

Treatment

Haplomesus franklinae View in CoL sp. nov.

Figures 1–6 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6

Material examined. Holotype. Australia, Vic., S of Point Hicks (38˚25´S, 149˚00´E), 1500 m, compacted clay, WHOI epibenthic sled, G.C.B. Poore et al., RV Franklin, 22 Jul 1986 (stn SLOPE 27 ), NMV J20300 View Materials (preparatory female, 6 mm).

Paratypes. Australia, Vic., 76 km S of Point Hicks (38˚29.33´S, 149˚19.98´E), 1840– 1750 m, sandy mud, fine shell, WHOI epibenthic sled, G.C.B. Poore et al., RV Franklin, 26 Oct 1988 (stn SLOPE 69 ), NMV J20303 View Materials (1 male, 6 mm); same data as holotype, NMV J40686 View Materials (1 female, 6 mm) .

Other material. NSW, 54 km ESE of Nowra (34˚52.72´S, 151˚15.04´E), 996– 990 m, mud, fine sand, fine shell (stn SLOPE 53 ), NMV J20301 View Materials (1 female). Off Nowra (34˚58.40´S, 151˚23.20´E), 1750– 1650 m, NMV J20305 View Materials (1 fragment). Off Nowra (34˚51.28´S, 151˚21.31´E), 1725– 1701 m, (stn SLOPE 13 ), NMV J20304 View Materials (1 fragment). 40° 45´S 149° 09.3´E; 3000– 2500 m (stn FR1086-4) Vic., 67 km S of Point Hicks (38˚23.95´S, 149˚17.02´E), 1277– 1119 m, fine mud (stn SLOPE 67 ), NMV J20302 View Materials (2 females, 5 fragments). 76 km S of Point Hicks (38˚29.33´S, 149˚19.98´E), 1840– 1750 m, sandy mud (stn SLOPE 69 ), NMV J40688 View Materials (2 males, 15 females, 41 fragments). S of Point Hicks (38˚25´S, 149˚0´E), 1500 m, compacted clay (stn SLOPE 27 ), NMV J40687 View Materials (2 females, 2 fragments) GoogleMaps .

Diagnosis. Body granulate, about 6 times as long as wide. Pereonite 1 with pair of long frontal-facing spines on anterolateral margin and pair of stout dorsal spines on posterior margin. Pereonites 2–4 each bearing pair of anterolateral spines, posterolateral margins of pereonites 5–7 rounded. Pereonites 4 and 5 about 2 and 7 times as long as pereonite 2 respectively. Pleotelson longer than broad, with wide dorsal keel. Antenna 1 of 6 articles, article 2 13 times as long as wide, 0.6 times as long as entire antenna 1, bearing 3 long flagellate setae and 1 aesthetasc. Antenna 2 article 3 more than twice as long as article 4. Mandible covered with microtrichs, molar elongate, with many small circular pits. Maxilliped palp articles 2 and 3 expanded, narrower than basal endite. Pereopod 1 carpus inferior margin with 1 simple seta, 2 long, robust flagellate setae and 1 long robust seta; propodus inferior margin with 2 short flagellate robust setae. At least pereopods 2–4 carpi with finely serrate distal margin. Pleopod 3 exopod with microtrichs, lateral margin with fringe of fine setae. Uropod of 2 articles, article 1 0.5 times length of article 2; article 2 with 1 brush seta.

Description of female holotype. Body length 6.3 times maximum width of pereonite 3 (excluding spines); cuticle calcified, brittle and granulated, all pereonites bearing numerous short simple setae. Head+pereonite 1 1.1 times as wide as long, with 2 anterolateral spines each as long as head+pereonite 1 and 2 short dorsal spines extending from medial ridge. Ratio of lengths of pereonite 2: pereonite 3: pereonite 4: pereonites 5+6+7+pleon (together), 1.0:1.1:1.9:12.1. Pereonite 2 slightly wider than pereonite 1, with transverse ridge. Pereonites 2–7 progressively decreasing in width posteriorly. Pereonites 2–4 each with pair of anterolateral spines. Anterolateral spines on pereonites 2 and 3 0.4 times as long as spines on pereonite 1; spines on pereonite 4 0.2 times as long as those on pereonite 1. Posterolareral margins on pereonites 5–7 rounded. Pereonites 5–7 and pleon with faint suture lines present at joins of these pereonites on dorsal surface, ventral surface fused completely. Pleotelson broad, dorsally with wide longitudinal ridge. Posterior margin rounded, swollen, with 2 medial subventral lobes.

Antenna 1 article 1 with 3 simple setae and 1 brush seta; article 2 4.0 times as long as and 0.2 times as wide as maximal width of article 1, with 8 simple setae of different lengths, 3 long flagellate setae, 1 brush seta and 1 distal aesthetasc; article 3 0.7 times as long as article 1, with 1 simple seta; article 4 0.6 times as long as article 1, with 3 simple setae and 1 brush seta; article 5 0.5 times as long as article 1, without setation; article 6 0.4 times length of article 1, with 5 distal simple setae. Antenna 2 article 1 quadrangular, without setae; article 2 approximately 0.6 times as long as longest margin of article 1, with no setae; article 3 elongate, about 4.3 times as long as article 1, with at least 11 simple setae; article 4 about 1.7 times as long as article 1, with 3 simple setae and few spinules on distal margin.

Mandible surface covered with microtrichs; incisor process with 5 cusps; lacinia mobilis with 2 cusps; spine row of 6 spines; molar long, rectangular, with numerous, small round pits, 9 fine simple setae on inferior margin and 5 fine simple setae on proximal margin. Maxilla 1 with both lobes bearing numerous microtrichs and fine simple setae on both margins; mesial lobe 0.9 times as wide as lateral lobe, with 1 dentate and 1 distal simple seta; lateral lobe with fine simple setae and microtrichs on surface and 12 distal, robust, dentate setae. Maxilla 2 lateral and middle lobes of equal width, lateral lobe with clusters of microtrichs on surface and 5 simple setae on inferior margin; lateral and middle lobes both with 4 distal pectinate setae of different lengths; mesial lobe 2.8 times as wide as lateral lobe, with many microtrichs and scale-setae covering surface, 2 long pectinate setae set medially on inferior margin, and distally, 4 dentate, 2 pectinate and 6 simple setae. Maxilliped coxa small, narrow, oblong; basis 1.8 times as long as widest point, with fine simple setae and 1 simple seta each on lateral margin and surface, endite with 3 coupling hooks and distally 3 fan, 5 simple and many fine simple setae. Palp tapering, 2.6 times as long as basal endite; palp article 1 shortest, subrectangular, with few fine simple setae and 1 simple seta; article 2 0.6 times as wide as endite at maximum width, 2.1 times as long and 1.3 times as wide as article 1, with microtrichs on both margins, 2 simple setae and 1 small robust seta; article 3 width and length equal to that of article 2 surface and superior margin with microtrichs and 2 short setae and inferior margin with fringe of fine simple and 3 longer simple setae; article 4 much narrower than article 3, 1.6 times as long as article 1, with few microtrichs and 2 simple setae on distal margin; article 5 length equal to article 4 but narrower, bearing 5 simple setae and 1 thick distal seta. Epipod elongate, semicircular, length 3.5 times width and 1.1 times basis length.

Pereopod 1 basis 0.1 body length; ratio of lengths of articles, basis to dactylus, 1.0:0.4:0.2:0.4:0.3:0.3; basis with 12 scattered simple setae; ischium with 3 long and 2 short simple setae; merus with 1 long and 1 short seta on distal superior margin and 1 simple, 1 flagellate robust and 1 long robust seta on distal inferior margin; carpus width subequal, superior margin with 3 long, simple slender setae, inferior margin with 1 simple and 2 long flagellate robust setae on proximal half, and more distally with 1 robust seta; propodus width subequal throughout, superior margin with 3 long simple setae and 4 smaller simple setae, 1 simple seta set medially and inferior margin with 1 distal simple seta and 2 robust flagellate setae; dactylus with 4 simple setae on distal superior margin. Pereopods 2, 3 and 5–7 missing.

Pereopod 4 basis 0.2 body length; ratio of lengths of articles, basis to dactylus, 1.0:0.6:0.2:0.8: 0.5:0.2; basis with 22 scattered simple setae; ischium with 10 scattered simple setae; merus with 5 simple setae; carpus with 6 simple setae and 1 distal brush seta on superior margin, 2 simple setae set medially, 3 robust flagellate setae and distally, 1 long robust seta on inferior margin, distal margin finely serrate; propodus superior margin with 7 simple setae and 1 brush seta, inferi- or margin with at least 5 flagellate robust setae, 1 long robust seta and 1 simple seta; dactylus with 4 simple setae on superior margin.

Additional pereopods from female paratype. Pereopod 1 articles, length ratios same as in holotype; basis with 5 simple setae scattered; ischium with 3 simple setae; merus same as that of holotype, carpus width generally subequal throughout distally, widens slightly proximally, with 2 long and 1 short simple setae on superior margin, inferior margin setation same as holotype; propodus width subequal throughout, with 3 long simple setae and at least 1 smaller simple seta on superior margin, medially 2 simple setae and inferior margin with 2 robust flagellate setae; dactylus same as in holotype.

Pereopod 2 ratio of lengths of articles, basis to dactylus, 1.0:0.4:0.2:0.6:0.3:0.3; basis with 3 robust flagellate setae and 1 brush seta proximally, and 7 simple scattered setae; ischium with 4 simple setae; merus with 4 simple setae; carpus with 1 simple seta on superior margin and 1 on inferior margin, 2 robust flagellate setae and 1 long robust setae, distal margin finely serrate; propodus bearing 1 simple setae proximally, 1 short robust flagellate and 1 long robust seta on inferior margin and distally 3 simple setae, 1 brush seta and 1 robust flagellate setae and 1 long robust seta; dactylus with 4 short setae on superior margin.

Pereopod 3 ratio of lengths of articles, basis to dactylus, 1.0:0.6:0.1:0.8:0.5:0.3; basis bearing 3 proximal robust flagellate setae, 1 brush seta and 6 scattered simple setae; ischium with 4 simple setae; merus with 3 simple setae; carpus with 4 simple setae and 1 brush seta on superior margin, and inferior margin with 2 flagellate robust and 1 long distal robust setae, distal margin finely serrate; propodus with 1 simple seta on superior margin, inferior margin with 2 robust flagellate setae and 1 long robust setae with few fringed scales in between and distally with 1 robust flagellate, 1 brush and 2 simple setae; dactylus bearing 4 short setae on superior margin.

Pereopod 4 ratio of article lengths similar to that of holotype; basis bearing 13 simple and 2 brush setae; ischium with 7 simple setae; merus with 5 simple setae; carpus with 5 simple setae, 2 robust flagellate setae and 1 distal brush seta, distal margin finely serrate; propodus with 2 medial simple setae and on inferior margin 2 robust flagellate, 1 long and 1 short robust seta and 4 simple and 1 robust setae distally; dactylus same as in holotype.

Pereopods 5–7 missing.

Operculum length 0.9 times maximum width; numerous simple setae on both lateral margins and scattered on ventral surface, 9 long, plumose setae on posterior margin. Pleopod 3, exopod 0.8 times length of endopod, with few surface microtrichs and fringe of fine simple setae on superior margin. Pleopod 4 length 1.5 times width.

Uropod straight, 0.5 times length of pleotelson; article 1 short, with at least 5 simple setae; article 2 twice as long as article 1, tapering, with 3 simple setae and 1 brush seta.

Male. Pleopod 1 proximal end damaged; lateral margins indented, distal portion covered with microtrichs; medial keel extends distally with 4 simple setae on each side of suture line; distal margin with 5 simple setae on both left and right sides; prominent distolateral horns. Pleopod 2 sympod length 2.4 times maximum width; lateral margin curved with 7 simple setae and 6 distolateral plumose setae; exopod a small lobe, 0.2 times length of sympod; stylet 0.3 length of sympod, narrowing to a point; sperm duct 0.6 length of stylet. Pleopods 3 and 4 similar to female.

Distribution. South-eastern Australia, from Nowra, New South Wales, to Point Hicks, Victoria; 990–1840 m depth.

Etymology. For the CSIRO Research Vessel Franklin, from which the material was collected.

Remarks. Haplomesus franklinae is the fifth species of this genus to be described from the Southern Hemisphere, and the first to be described from Australian waters. In body form it most closely resembles Haplomesus modestatenuis Menzies and George, 1972 , with both species having anterolateral spines on pereonites 1–4 and the posterior margin of the pleotelson with two medial subventral lobes. However, H. franklinae differs from H. modestatenuis in having stouter spines on pereonites 4 and 5, uropods with two articles that extend well past the pleotelson, lack of dorsal hooks on pereonite 7, and no robust setae on the posterolateral margins of the pleotelson ( Menzies and George, 1972).