Heteromysis (Heteromysis) keablei, Daneliya, 2021

Daneliya, Mikhail E., 2021, On the Mysid Crustacean Genus Heteromysis (Mysidae: Heteromysinae) of the Tasman Sea, with Notes on the Tribe Heteromysini, Records of the Australian Museum (Rec. Aust. Mus.) 73 (1), pp. 1-50 : 15-20

Heteromysis (Heteromysis) keablei sp. nov.

urn:lsid:zoobank.org:act:2C711FD7-E6EE-4B80-AECD-E3C9D5EE80E7

Figs 5−8

Etymology. Named after Stephen John Keable, a collection manager at the Australian Museum, for his assistance on various stages of this and other Australian mysid research, collecting numerous specimens for this study and for his contribution to the carcinology and marine biology.

Holotype. Male (+slide), 4.5 mm, north side of Burrewarra Point, south of Batemans Bay, 35°49'48"S 150°14'01"E, 22.2 m, 22.5°C, coarse sand and shell, dead barnacles, bryozoans, ascidians and solitary coral, 23 Mar 2004, coll. RV Baragula & RV Sula, NSW 2494 , P. Berents, K. Attwood, R. Johnson, S. Keable, S. Kiely, K. Monro, A. Murray, R. Springthorpe, J. Watson, airlift on SCUBA (Australian Museum P. 75281).

Paratypes. Female, 4.5 mm, juvenile, same data as for holotype ( AM P.98695); female, 4.5 mm, same locality, 35°49.776'S 150°13.955'E, 15 m, 22°C, rocky reef with sand patches and some large boulders with vertical faces, some patches of Ecklonia , under stones with small stones, very little sediment, 24 Mar 2004, NSW 2540, same collectors and gear ( AM P.98692); male, 4.5 mm, female, 4.5 mm, juvenile, same locality as previous, 35°49.776'S 150°13.955'E, 17 m, 22°C, rocky reef with sand patches and some large boulders with vertical faces, some patches of Ecklonia , under stones in sand, 24 Mar 2004, NSW 2538, same collectors and gear ( AM P.98693); male, 4 mm, female, 4.5 mm, 35°49.776'S 150°13.955'E, 17 m, 22°C, rocky reef with sand patches and some large boulders with vertical faces, some patches of Ecklonia , under stones in sand, 24 Mar 2004, NSW 2538, same collectors and gear ( AM P.98694); female, 5 mm, Jervis Bay, Hole in the Wall, 35°07'36"S 150°44'48"E, 12 m, 12 Nov 1989, coll. Jervis Bay Baseline Study ( CSIRO), site 1, #4 ( AM P.98696).

Additional specimens. Male (+slide), 6 mm, Hawkesbury River, near Hungry Beach , 33°35'S 151°17'E, 4 m, sandy mud, 9 Nov 1984, coll. A. R . Jones & A. Murray; HRS 1-1 Nov 84, Smith-McIntyre Grab ( AM P.53661); female, 6 mm, same data as in previous ( AM P.98706); 2 immature specimens, 4−4.5 mm, same locality, 33°35'S 151°17'E, 4 m, sandy mud, 11 Nov 1983, HRS 1-1 Nov 83, same collectors and gear ( AM P.53662); male, 4.5 mm, Botany Bay, 33°58'11"S 151°11'10"E, 18.4 m, sandy mud, 16 Dec 1994, coll. Australian Museum party, FAC2 07 Bot 2/1a ( AM P.59284); damaged specimen, west of Tollgate Islands, Batemans Bay, 35°44.827'S 150°15.42'E, 7 m, 22.1°C, patches of reef, stones and Ecklonia radiata , under large stones, 29 Mar 2004, coll. RV Baragula & RV Sula, NSW 2642 , P. Berents, K. Attwood, R . Johnson, S. Keable, S. Kiely, K. Monro, A. Murray, R . Springthorpe, J. Watson, airlift on SCUBA ( AM P.98697); 1 juvenile, Ulladulla, northern side of Bannister Head , 35°19.15'S 150°29.12'E, 18 m, 06 May 1997, coll. K. B. Attwood & R. T . Springthorpe, NSW 1347, airlift ( AM P.98698) .

Diagnosis. Rostrum ( Fig. 5A ) angular, apically blunt or rounded, reaching proximal part or half of antennular peduncle segment 1; its lateral margins slightly concave, without lateral tubercle, covering eyestalk bases. Eyestalk with only slight distomedial rim, not pointed; cornea slightly narrower than stalk, but not significantly reduced. Eye length 0.49−0.53 of head width. Telson ( Fig. 5C,D ) 1.0−1.2 times as long as abdominal somite 6, 1.2−1.3 times as long as wide, 0.18−0.19 times as wide posteriorly as anteriorly. Cleft 0.19−0.20 of telson length, with six to ten spinules, occupying 0.28−0.51 of cleft length. Telson lateral margins with 15 to 27 spiniform setae, occupying entire or almost entire sides, including two terminal spiniform setae, with wing-like extensions. Inner terminal spiniform setae 0.75−0.85 times as long as outer. Outer spiniform setae 0.09−0.16 times as long as telson and 1.2−1.4 times as long as last posterolateral spiniform setae. Antennular peduncle ( Fig. 5 F−H) segment 3 with two rather long flagellated spiniform setae. Antennal scale ( Fig. 5I ) 2.4−3.4 times as long as wide, stretching little beyond half of antennular peduncle segment 3 and beyond half of antennal peduncle segment 3. Pereopod 1 ( Fig. 7 A−E) ischium 1.7 times as long as wide; merus 3.4 times as long as wide and 2.0 times as long as ischium, medially with seven flagellated setae and distomedial process. Pereopod 1 carpopropodus segment 1 is 3.3 times as long as wide and 1.1 times as long as merus, its medial margin with seven smooth and a pair of smooth and shorter bifurcated spiniform setae; each of first six spiniform setae laterally provided with postero- and anterodistally serrated long seta; and distally with two stronger setae with posteroproximal serration; segment 2 without distomedial process, with three long paradactylary setae, proximally with thin long separate spinules and distally numerous short denticles. Dactylus 0.39−0.40 times as long as carpopropodus, meandering. Pereopod 2−6 ( Figs 7F , 8 A−D) carpopropodus 5−7-segmented; unguis rather thin, smooth. Pereopod exopod basal segment without outer acute process. Penis ( Fig. 8E ) with two or three anterodistal and one or three posterodistal setae. Uropodal endopod ( Fig. 5E ) 0.78−0.89 times as long as exopod, with 16 to 27 medial spiniform setae, closely set along entire margin.

Body length of male 4.0−6.0 mm, female 4.5−6.0 mm.

Comparison. In the microps -group, Heteromysis (Heteromysis) keablei sp. nov. is most similar to Heteromysis (H.) nomurai , and Heteromysis (H.) sahulensis . It differs from the first species (found in the Japanese waters) by the shorter rostrum, which is nearly reaching the distal margin of the antennular peduncle segment 1 and uniquely has a pair of lateral tubercles or swellings above the eyestalk in H. nomurai ; the shorter telson (1.5 times as long as the last abdominal somite in H. nomurai ); and larger number of the telson lateral spiniform setae (15 to 27 against 13, which occupy the posterior part of the telson in H. nomurai ); the telson terminal spiniform setae clearly longer than the last posterolateral spiniform setae (as long as or shorter in H. nomurai ); the ischium of the pereopod 1 smooth (with small flagellated setae in H. nomurai ); less number of the penis setae (about ten posterior setae in H. nomurai ); a larger number of the uropodal endopod spiniform setae (16 to 27 against 12 to 14 in H. nomurai ). In the microps - group, Heteromysis (H.) keablei shares the largest number of the spiniform setae on the medial margin of the uropodal endopod, set rather close to each other, with Heteromysis (H.) sahulensis . From this species it is distinguished by less developed distomedial rim of the eyestalk (rather strongly developed in H. sahulensis ); relatively large cornea (notably reduced in H. sahulensis ); less prolonged telson (1.2−1.3 as long as proximal width against 1.5 in H. sahulensis ); posteriorly more narrowing telson, with the posterior width 0.18−0.19 times the anterior width (0.3 in H. sahulensis ); shallower telson cleft (0.19−0.20 times as long as telson against 0.3 in H. sahulensis ); fewer cleft spinules (6 to 10 against 24 H. sahulensis ); occupying less than a half of the cleft (0.7 in H. sahulensis ); two against anomalously one terminal spiniform setae in H. sahulensis ; longer antennal scale, extending beyond the middle of the antennular and antennal peduncles segment 3 (reaching only the proximal part in H. sahulensis ); the uropodal endopod clearly shorter than the exopod (nearly equal in H. sahulensis ).

Description of holotype. Rostrum triangular, apically blunt, reaching half of peduncle segment 1 of antennula; lateral margins slightly concave, covering bases of eyestalks. Posteroventral margin of abdominal somite 6 serrated. Telson about as long as last abdominal somite, 1.2 times as long as wide anteriorly, tapering posteriorly, 0.19 times as wide posteriorly as anteriorly. Telson cleft 0.2 times of entire telson length, with ten spinules, occupying about half of cleft; lateral margins slightly sinusoid, with 20 and 21 spiniform setae, including two apical, with distal wing-like expansions; outer terminal spiniform setae 1.5 times as long as inner. Lateral spiniform setae absent in anterior part of telson.

Eyes flattened dorsoventrally, nearly rounded from dorsal view; eye length about 1.0 eye width, and 0.6 times anterior head width. Cornea 0.7 times as wide as stalk and 0.3 times of entire eye length. Antennular peduncle segment 3 with two long flagellated setae, one of them directed laterally. Antennal scale rather wide, 2.4 times as long as wide, reaching level of about half of antennal and antennular peduncles segment 3 or slightly beyond that.

Labrum produced, apically rounded, with keel. Mandibular palp, segment 2 with setae along entire posterior margin; segment 3 with two posterior and two medial setae in distal half. Maxilla 1 outer ramus with smooth apical spiniform setae. Thoracopod exopods 9-segmented; basal segment without acute outer process. Maxilliped 2 carpopropodus 0.7 times as long as merus.

Pereopod 1 endopod. Ischium 1.7 times as long as wide, only with short and fine posterior seta. Merus 3.4 times as long as wide and 2.0 times as long as ischium; its medial margin with seven strong flagellated setae and distal sharp process. Carpopropodus segment 1 is 3.3 times as long as wide and 1.1 times as long as merus; its medial margin with seven smooth and a pair of smooth and shorter bifurcated spiniform setae; each of first six spiniform setae laterally provided with postero- and anterodistally serrated long seta; and distal two stronger setae with posteroproximal serration; segment 2 without distomedial process, with three long paradactylary setae, proximally with thin long separate spinules and distally numerous short denticles. Dactylus 0.39−0.40 times as long as carpopropodus, with meandering unguis.

Pereopod 3−6 endopods rather thin and long. Preischium without or with two setae. Ischium only slightly longer and wider than merus, with setae along anterior and distal half of posterior margins (along entire posterior in pereopod 6). Merus posterior margin with five pairs and single intermediate setae. Carpopropodus 0.7−0.8 times as long as merus, with five or six prolonged segments. Paradactylary setae and unguis rather thin and smooth.

Penis with three anterior and two posterior setae. Pleopods with seven or eight setae along rather short ramus. Uropod endopod shorter than exopod, with 20 and 22 rather short and closely set spiniform setae on medial margin.

Color. From a rather low resolution photograph, made soon after the sampling, which I do not publish here, it is possible to see that a living specimen had a transparent cuticle, without any coloration. Eye cornea black.

Variation. The specimens from near Sydney (Hawkesbury River Mouth and Botany Bay) differ from the specimens of the southern New South Wales coast (Batemans Bay and Jervis Bay) by the rostrum shape (apically rounded against blunt), narrower antennal scales (3.2−3.4 against 2.4 times as long as wide) and a larger number of the telson lateral spiniform setae (25 to 27 against 15 to 23), spread along the entire margins (the spiniform setae absent in the most anterior part of the telson in the southern NSW). I hesitate in establishment of separate taxonomic status for the Sydney specimens before larger and more extensive material is collected.

Distribution. Australia, New South Wales: Batemans Bay (type locality), Ulladulla, Jervis Bay, Hawkesbury River Mouth, Hungry Beach, Botany Bay. So far recorded only in the Tasman Sea ( Fig. 4B ).

Habitat and life history. Sublittoral species, found at a depth of 4−22 m. Bottom: rocky reefs with coarse sand and shell, large boulders with vertical faces, dead barnacles, bryozoans, ascidians and solitary coral, patches of brown alga Ecklonia radiata ; found under stones with small stones and very little sediment or under stones in sand; sandy-muddy bottom. Marsupium of a 4.5 mm female from Batemans Bay contained three embryos on 23 March and at temperature of 22.5°C .

Figures

Figure 4. Distribution of the Tasman Sea Heteromysis (Heteromysis) species. (A) general distribution of H. (H.) communis and H. (H.) tasmanica (the white signs indicate former records); (B) H. (H.) communis, H. (H.) keablei sp. nov., H. (H.) macropsis and H. (H.) tasmanica in the Tasman Sea.

Figure 5. Heteromysis (Heteromysis) keablei sp. nov., holotype, male, 4.5 mm, AM P.75281: (A) head, dorsal; (B) abdominal somite 6 posteroventral margin; (C) telson; (D) telson posterior part; (E) uropod, dorsal; (F) distomedial spiniform setae of antenna 1 peduncle segment 3; (G) distomedial spiniform setae of antenna 1 peduncle segment 2; (H) segment 3 of antenna 2 peduncle, ventral; (I) antennal scale. Scales (mm): A−E, I = 0.5; F−H = 0.25.

Figure 6. Heteromysis (Heteromysis) keablei sp. nov., holotype, male, 4.5 mm,AM P.75281: (A) mandible, left; (B) labrum, posterior; (C) maxilla 1, posterior; (D) maxilla 2, anterior; (E) maxilliped 1, anterior; (F) maxilliped 2, posterior; (G) maxilliped 2 distal part, posterior. Scales (mm): A, C−F = 0.5; B, G = 0.25.

Figure 7. Heteromysis (Heteromysis) keablei sp. nov. (A, C, F) holotype, male, 4.5 mm, AM P.75281; (B, D, E) paratype, male, 4.5 mm, AM P.98693. (A) pereopod 1 endopod, posterior; (B) pereopod 1 endopod, posterior; (C) distal seta of pereopod 1 carpopropodus segment 2; (D) distolateral seta of pereopod 1 carpopropodus segment 1; (E) posterolateral seta of pereopod 1 carpopropodus segment 1; (F) pereopod 3. Scales (mm): A, F = 0.5; B = 1; C−E = 0.25.

Figure 8. Heteromysis (Heteromysis) keablei sp. nov., holotype, male, 4.5 mm, AM P.75281. (A) pereopod 4 endopod, posterior; (B) pereopod 5 endopod, anterior; (C) pereopod 6, anterior; (D) distal part of pereopod 6 endopod, anterior; (E) penis; (F) pleopod 2, posterior; (G) pleopod 3, posterior; (H) pleopod 4, posterior; (I) pleopod 5, posterior. Scales (mm): A−C = 0.5; D−I = 0.25.