Heteromysis (Olivemysis) abrucei Băcescu, 1979

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 : 35-40

Heteromysis (Olivemysis) abrucei Băcescu, 1979

Figs 18−21

Heteromysis (Olivaemysis) abrucei Băcescu, 1979: 143 , fig. 1A−I (incorrect spelling in the subgeneric name).— Băcescu & Müller, 1985: 9, fig. 1I−P.— Fenton, 1986: 203, 145, fig. 2.51H, I.— Murano, 1988: 27, 35, 36, 46.

Heteromysis abrucei . — Băcescu & Bruce, 1980: 71.— Neyt, 2002: 11.— Hanamura & Kase, 2001a: 18.

Heteromysis (Olivemysis) abrucei .— Lowry & Stoddart, 2003: 448.— Price & Heard, 2011: 44.— Daneliya, 2012: 136, 141, 417.— San Vicente & Monniot, 2014: 336.— Wittmann & Abed-Navandi, 2019: 94; 2021: 137, 139.

Heteromysis (Heteromysis) abrucei .— Petrescu & Wittmann, 2009: 59.

Type specimens. Holotype, male, 5 mm, Australia, Queensland, Great Barrier Reef, near Heron Island, Moore Reef, st. 563, on coral Acropora , 30 Dec 1976, coll. A. J. Bruce ( MGAB 49192). M. Băcescu was planning to deposit the holotype at the AM ( Băcescu, 1979), but eventually put them at the MGAB ( Petrescu & Wittmann, 2009). He also mentioned an allotype female and a paratype male from the same sampling, but neither has been found in any museum collections.

Tasman Sea material. Male (+slide), female, Inflammable Liquids Berth, Port Kembla Outer Harbour , 34°27'57"S 150°54'15"E, 0.5 m, pylon/piling scraping, 13 May 2000, coll. NSW Fisheries, PK ILB P3-0 ( AM P.63480; originally det. by G. C. B. Poore in 2000); 2 males, 5.5−6.5 mm, female, 6 mm, 4 subadult specimens (one without head), south end of No. 3 Jetty, Port Kembla Outer Harbour , 34°28'36"S 150°54'30"E, 0.5 m, pylon/piling scraping, 16 May 2000, coll. NSW Fisheries, PK J3O P2−0 ( AM P.63481; originally det. by G. C. B. Poore in 2000); damaged specimen, Port Jackson , White Bay east, 33°51'40"S 151°11'25"E, 3 m, scrapings from cement facing, 18 Apr 2001, coll. AM party—Sydney Ports Survey, Sydney Ports 51, hand collected on SCUBA ( AM P.62274; originally det. by R. T. Springthorpe in 2001); 2 females, 5.5−6 mm, Port Jackson , Garden Island east, 33°51'45"S 151°13'47"E, 3 m, scrapings from metal struts, 21 May 2001, same collector and gear, Sydney Ports 28 (P.62273; det. R. T. Springthorpe in 2001); 8 females, 4.5−6 mm, 3 damaged specimens, 2 cephalothoraces, 7 abdomens, Port Jackson , Chowder Bay , 33°50'29"S 151°15'20"E, 3 m, scrapings from cement piles, 6 Jun 2001, same collector and gear, Sydney Ports 14 (P.62272; det. R. T. Springthorpe in 2001); female, 5 mm, 2 damaged specimens, Port Jackson , Balls Head Bay north, 33°50'34"S 151°11'31"E, 3 m, on Mytilus galloprovincialis in scrapings from wooden piles, 24 Apr 2001, same collector and gear, Sydney Ports 1 (P.62271; det. R. T. Springthorpe in 2001); female, 6.5 mm, Botany Bay , Channel Marker 4, 33°59'18"S 151°12'36"E, 7 m, pylon scraping, 21 Oct 1998, coll. NSW Fisheries, BB CH 4 P1−7 (P.58593).

Diagnosis. Rostrum ( Fig. 18A ) angular, apically narrowly rounded to nearly pointed, reaching proximal or middle part of antennular peduncle segment 1; its lateral margins slightly concave. Eyestalk ( Fig. 18A ) with one distomedial spine; cornea slightly narrower or about as wide as stalk. Telson ( Fig. 18B ) slightly longer than last abdominal somite and 0.20−0.29 as wide posteriorly as anteriorly. Telson cleft 0.27−0.30 of telson length, with 17−19 spinules, occupying anterior 0.52−0.70 of cleft length. Telson lateral margins slightly sinusoid, with 14−27 spiniform setae, occupying entire length; among two terminal, inner spiniform setae 0.58−0.86 as long as outer; outer spiniform setae 0.10−0.13 as long as telson and 1.1−1.2 times as long as last posterolateral spiniform setae. Antennular peduncle ( Fig. 18A ) segment 2 with medial flagellated spiniform seta; segment 3 with two medial flagellated spiniform setae, one stronger and shorter or about as long as another thinner spiniform seta. Antennal scale ( Fig. 18E ) reaching proximal or middle part of antennular peduncle segment 3 and nearly reaching distal margin of antennal peduncle, 2.7−3.4 times as long as wide. Pereopod 1 endopod ( Fig. 19C,D ), ischium 1.6−1.8 times as long as wide, merus 2.5−2.7 times as long as wide and 1.5−1.9 as long as ischium, carpopropodus segment 1 is 1.8−2.3 times as long as wide and 0.69−0.71 times as long as merus, with three or four groups of two (proximal group may also have one) about equal smooth flagellated spiniform setae, dactylus with unguis 0.43−0.54 of carpopropodus; unguis smooth. Pereopod 2 ( Fig. 20A ) carpopropodus 3-segmented. Pereopod 3−6 ( Figs. 20B,E , 21A ) carpopropodus 6−9-segmented. Pleopods 3 and 4 of male ( Fig. 21C ) with 11−13 and 14−17 strong flagellated setae, respectively. Uropodal endopod ( Fig. 18D ) with two to four proximal spiniform setae.

Comparison. The species is not known to have any unique characters. It is most similar to H. (O.) brucei , found in Seychelles, from which H. abrucei differs by larger number of the telson lateral spiniform setae (17−27 against 11−15), fewer uropodal endopod spiniform setae (two to four against five), the smooth spiniform setae of the carpopropodus of the pereopod 1 and its dactylar unguis (uniquely serrated in H. brucei ), the broader pereopod 1 merus (2.5−2.7 times as long as wide, compared to 4.4 in H. brucei ), with about ten rather long medial setae in the middle part (only two in H. brucei ). It is also rather close to H. (O.) essingtonensis Murano, 1988 , from the northern Australian coast, from which it differs by the presence of the distomedial spine on the eyestalk (absent in H. essingtonensis ), slightly more spinules in the telson cleft (17−19 against 12 in H. essingtonensis ), but less spiniform setae on the uropodal endopod (two−four against 13−15 in H. essingtonensis ).

Description of Tasman Sea specimens. Rostrum angular, apically narrowly rounded to nearly pointed (Botany Bay and Port Jackson), as in type specimens, covering eye stalk bases. Eye stalk with strong distomedial spine. Cornea nearly as wide as distal part of stalk. Telson slightly (1.1) longer than last abdominal somite, 1.02 times as long as wide anteriorly and 4.9 times as wide anteriorly as posteriorly. Telson lateral margins entirely with 20−27 spiniform setae (14−22 in the Coral Sea and 17−20 in Somali), including two apical, with outer spiniform setae slightly bent outwards; inner apical spiniform setae 0.6−0.7 as long as outer. Telson cleft rather deep, 0.3 of telson length, with parallel margins and 17−19 spinules in anterior half (same as in Somali and 20 in the types). Antennular peduncle rather strong; segment 2 with distomedial flagellated seta; segment 3 with two distomedial flagellated setae, one of them stronger, directed slightly inward, nearly as long as another, weaker, directed outward, and two simple setae directed forward. Antennal scale nearly reaching distal margin of antennal peduncle segment 3, and half of antennular peduncle segment 3 (reaching proximal part in type specimens), its length 2.5 width (3.0 in the types and 2.7 in Somali). Mandibular palp as typical for the genus. Maxilla 1 outer ramus with three caudal setae and about 14 strong spiniform setae. Maxilla 2, exopod with 23 short setae, endopod segment 2 with plumose outer and serrated inner setae. Maxilliped 1 typical for the genus; exopod 8-segmented. Maxilliped 2 endopod, carpopropodus 0.8 times as long as merus; dactylus about as wide as carpopropodus, with about 10 serrated setae. Pereopod 1 endopod, merus 2.8 times as long as wide and 1.6 times as long as ischium; carpopropodus segment 1 is 2.1−2.3 times as long as wide and 0.7 times as long as merus, distomedially with six to eight paired flagellated setae, and sometimes with additional distomedial setae; unguis twice as long as dactylus, smooth. Carpopropodus of pereopod 2 is 3-segmented, with long setae, 0.8 times as long as merus; segment 1 is 1.2 times as long as segments 2 and 3 together. Pereopod 3−6 exopod 10-segmented; endopod merus 0.9 times as long as ischium and carpopropodus 0.8−0.9 times as long as merus; carpopropodus 6−9-segmented (7-segmented in the type material and in Somali); dactylar unguis serrated; paradactylary setae smooth, sickle-shaped. Penis tubiform, with short finger-like apical lobes. Pleopods 3 and 4 of male with 13−15 strong flagellated setae (15 in pleopod 4 in Somali specimens, and 11 and 17, in pleopod 3 and 4, respectively, in the types). Pleopod 5 with setae about half as long as ramus. Uropodal endopod 0.8 the length of exopod, with three or four medial spiniform setae in proximal part (two or three in the type specimens, and four in Somali).

Body length of males 5.5−6.5 mm, females 4.6−6.5 mm (3.5−5.0 mm in the type locality).

Color. In the Coral Sea, Băcescu (1979) and Băcescu & Bruce (1980) reported generally translucent whitish or uniform golden tegument; the carapace, abdomen, antennal peduncles, anterior parts of eyestalks and telson with small red dots; the eye cornea white. Similar coloration was described for Heteromysis (Olivemysis) brucei , H. (O.) dardani Wittmann, 2008 , H. (O.) ningaloo Daneliya, 2012 and H. (O.) wirtzi Wittmann, 2008 . The Somali specimens of H. abrucei were shown to have generally pink body and dark red eyes ( Băcescu & Müller, 1985).

Distribution. West Indo-Pacific. Coral Sea. Australia, Queensland: southern Great Barrier Reef, Heron Island, Moore Reef (type locality) ( Băcescu, 1979; Băcescu & Bruce, 1980). Tasman Sea. Australia, New South Wales: Port Jackson ( Hutchings et al., 2013), Botany Bay, Port Kembla (new material) ( Fig. 22 ). West Indian Ocean. Somalia ( Băcescu & Müller, 1985).

Habitat and life history. Upper sublittoral species, found at depths of 0.5− 7 m. Originally, it was found on the coral Acropora sp. ( Băcescu, 1979) , subsequently also collected from a nearby location on corals and reef flats ( Băcescu & Bruce, 1980). In Somali, it was found on sand among coral reefs ( Băcescu & Müller, 1985). In this study, all the material comes from scraping of metal, wooden and cement structures in harbours, probably indicating its ecological plasticity, and ability to live away from coral reefs in cooler sea. Females from the Coral Sea had two and four embryos ( Băcescu & Bruce, 1980).

abrucei and H. (O.) murrayae sp. nov. in the Tasman Sea.

Remarks. The species was described from the Coral Sea in detail and included in the subgenus Olivemysis (as Olivaemysis) by Băcescu (1979). It was distinguished from the most similar species, H. (O.) brucei comb. nov., known only from Seychelles, West Indian Ocean, by larger size (5 mm against 3−4 mm), larger number of the telson lateral spiniform setae (20 against 11), but less number of the uropodal endopod spiniform setae (three against five). Later, more specimens were collected from the nearby locality ( Băcescu & Bruce, 1980), with body length 3.5−4.5 mm, making it indistinguishable from H. brucei by size, 14 or 15 telson lateral spiniform setae (intermediate between the types and H. brucei ) and only two uropodal endopod spiniform setae. Băcescu & Müller (1985) reported H. abrucei from Somalia in the West Indian Ocean. The specimens had 17−20 lateral spiniform setae on the telson and four spiniform setae on the uropodal endopod (approaching even closer in this character to H. brucei ). Apart from the difference in coloration, the specimens from Somalia were surprisingly similar to the Australian specimens. The specimens from the Tasman Sea that I inspected had 20−27 telson lateral spiniform setae, and three or four spiniform setae on the uropodal endopod. Thus, only the number of the lateral spiniform setae of the telson remained to distinguish the two species. On the other hand, comparing H. abrucei with H. brucei, Băcescu (1979) overlooked that the spiniform setae of carpopropodus of pereopod 1 and its dactylar unguis were serrated (as described and illustrated by O. S. Tattersall, 1967), the first character extremely rare and the second unique for the subgenus Olivemysis . In addition, the pereopod 1 merus was rather slender (4.4 times as long as wide, compared to 2.5−2.7 in H. abrucei ), with two rather long medial setae in the middle part (about 10 along the margin in H. abrucei ). So far, nothing is known about the structure of the male pleopods in H. brucei . Formally, H. brucei was not considered part of the subgenus, although originally discussed as the most similar to H. abrucei . Despite the absence of data on the pleopods, I change its status here and include it into Olivemysis due to the presence of the distomedial flagellated spiniform setae on the antennular peduncles, the distomedial spine on the eyestalk and typical for Olivemysis form of the pereopod 1 endopod. In Murano’s (1988) opinion, H. (O.) quadrispinosa Murano, 1988 , and even more H. (O.) essingtonensis , were closely related to H. abrucei . He distinguished the second species by the narrowly rounded anterior margin of the carapace (obtusely pointed in H. abrucei ), the absence of the distomedial spine on the eyestalk (present in H. abrucei ), the uropodal endopod with 13−15 spiniform setae (against three or, as we can see from the previous and our findings, two to four spiniform setae). The Tasman Sea specimens have the narrowly rounded anterior margin of the carapace. Thus, the two species are similar by this character too. Hanamura & Kase (2001a) summarized the known key characters of H. abrucei together with other Indo-Pacific species. For some reason, H. abrucei was included into the subgenus Heteromysis s.str. by Petrescu & Wittmann (2009), although it was originally described and subsequently treated as part of Olivemysis by all the workers, including subsequent mentions ( Price & Heard, 2011; Daneliya, 2012). Considering previous studies, I also mentioned that H. abrucei had the pointed anterior margin of the carapace ( Daneliya, 2012), but from the new material we can see that this character is rather variable even within the Tasman Sea, and it can also be narrowly rounded, with the lateral margins covering the eyestalk bases, not noticed in the type specimens. In addition, the new specimens had the antennal scales reaching half of the antennular peduncle segment 3. I also expressed an opinion that H. abrucei was one of the most similar species to H. (O.) ningaloo Daneliya, 2012 . Wittmann & Abed-Navandi (2019) described H. (O.) domusmaris Wittmann et Abed-Navandi, 2019 , and compared it also with H. abrucei . The new species was reported to be distinguished by the flagellated spiniform setae on the segments 1 and 2 of the antennular peduncle, the presence of the outer spiniform extension on the antennal sympod, the apically more rounded rostrum, the greater number of the flagellated spiniform setae on the male pleopod 4, and by an interrupted series of fewer spiniform setae on the lateral margins of the telson. From the Tasman Sea collection we can now see that H. domusmaris differs from H. abrucei by the three characters: 1, the presence of the flagellated spiniform setae on the segment 1 of the antennular peduncle; 2, the greater number of flagellated spiniform setae on the male pleopod 4; and 3, the interrupted series of fewer spiniform setae on the lateral margins of the telson. Based on comparison with all species of Olivemysis , I provide here a revised diagnosis of H. abrucei with inclusion of more characters and compare it with the most similar species.

Figures

Figure 18. Heteromysis (Olivemysis) abrucei Băcescu, 1979, male, Tasman Sea, New South Wales, Port Kembla,AM P.63480. (A) head, dorsal; (B) posterior part of body with telson and uropods, dorsal; (C) posteroventral margin of abdominal segment 6, and uropodal protopod; (D) uropodal endopod, ventral; (E) antennal peduncle and scale, ventral view; (F) mandibular palp, anterior; (G) maxilla 1, anterior; (H), maxilla 2, posterior. Scales (mm): A, B = 1; C−H = 0.5.

Figure 19. Heteromysis (Olivemysis) abrucei Băcescu, 1979, male, Tasman Sea, New South Wales, Port Kembla, AM P.63480. (A) maxilliped 1, anterior; (B) maxilliped 2 endopod, posterior; (C) pereopod 1 endopod, posterior; (D) distolateral spiniform setae (one side) of pereopod 1 carpopropodus segment 1, posterior. Scales (mm): A−C = 0.5; D = 0.25.

Figure 20. Heteromysis (Olivemysis) abrucei Băcescu, 1979, male, Tasman Sea, New South Wales, Port Kembla, AM P.63480. (A) pereopod 2 endopod, anterior; (B) pereopod 3 endopod, anterior; (C) distal part of pereopod 3 endopod, anterior; (D) pereopod 5, exopod and proximal part of endopod, anterior; (E) pereopod 5, distal part of endopod, anterior. Scales (mm): A, B, D, E = 0.5, C = 0.25.

Figure 21. Heteromysis (Olivemysis) abrucei Băcescu, 1979, male, Tasman Sea, New South Wales, Port Kembla, AM P.63480. (A) pereopod 6 endopod, posterior; (B) penis; (C) pleopod 3, anterior; (D) pleopod 5, anterior. Scales (mm): A−D = 0.5.

Figure 22. Distribution of the Tasman Sea Heteromysis (Olivemysis) species. (A) H. (O.) abrucei and H. (O.) murrayae sp. nov. in the Australian waters (the white sign indicates former record); (B) H. (O.)