Heteromysis (Gnathomysis) harpaxoides Băcescu et Bruce, 1980

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 : 31-34

Heteromysis (Gnathomysis) harpaxoides Băcescu et Bruce, 1980

Fig. 16

Heteromysis (Gnathomysis) harpaxoides Băcescu et Bruce, 1980: 68 , figs 2M−N, 3A−H.— Murano, 1988: 27, 41, 48.— Vannini et al., 1993: 190.—Hanamura & Kase, 2001: 18.— Lowry & Stoddart, 2003: 446.— Wittmann, 2008: 369.— Petrescu & Wittmann, 2009: 58.— Daneliya, 2012: 135, 136, 141−146, figs 28−53.— San Vicente & Monniot, 2014: 337.

Heteromysis harpaxoides . — Müller, 1993: 270.— Hanamura, 2007: 35, 37−38, fig. 2.— Wittmann et al., 2014: 201, 349, fig. 54.4M.

Type specimens. Holotype, male, Australia, Great Barrier Reef , Wistari Reef, st. 563, 01 Feb 1979, coll. A. J. Bruce & B. Coates ( MGAB 49322 ) . Allotype, female, same data as holotype ( MGAB 49375 ) . Paratypes, male, female, same as previous ( MGAB 49375 ) ( Petrescu & Wittmann, 2009) .

Tasman Sea material. Male , 8.5 mm, female, 8 mm, 5 subadult specimens, 3.5−4 mm, Coral Sea , Coral Sea Islands, Middleton Reef , bommie east of lagoon entrance, 29°27'48"S 159°5'6"E, inside dead clam shell, 06 Dec 1987, coll. Elizabeth & Middleton Reefs Expedition, 1987, site 11 (P.38239) (det. by J. K. Lowry in 1988 as Heteromysis cf. tethysiana ); male (photographed), 7.5 mm, north of Tathra, south of Baronda Head, 36°41'12"S 149°59'53"E, 9.2 m, 17 C, 5 Apr 2008, coll. RV Baragula, MI NSW 3287, K. B. Attwood, airlift on SCUBA (P.77631) ; 1 specimen (only pereopod 1), 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, scraping ( AM P.99046) .

Diagnosis. Head part of carapace dorsally smooth, without tubercles. Telson 1.5−1.7 times as long as last abdominal segment, and 1.6−1.8 times as long as wide anteriorly. Eye cornea narrower than stalk. Antennal scale reaching half of antennular peduncle segment 3. Pereopod 1 merus medial inner and outer margins roughly serrate, without spiniform setae. Carpopropodus medial margin with three or four strong, finely serrated proximal spiniform setae and three or four roughly serrated distal spiniform setae, without gap between proximal and distal groups.

Body length of males 4.5−5 mm, female 6 mm.

Comparison. Heteromysis (Gnathomysis) harpaxoides is most similar to H. (G.) stellata , found on the hermit crab Aniculus sp. , and is still known only from the original publication and its type locality (Coral Sea, Heron Island, Queensland). It differs only by the absence of the tubercles of the head part of the carapace (four rows of white-bluish tubercles on pink-white background in H. stellata ). The species of the subgenus Gnathomysis have not significantly diverged morphologically from each other, mostly differing in the structure of the pereopod 1 endopod.

Description of Tasman Sea specimens. Rostrum triangular, apex almost acute, reaching half of antennule peduncle segment 1; lateral margins covering eyestalk bases. Posterolateral lobes of carapace nearly reaching posterior margin of first abdominal somite. Posteroventral margin of last abdominal somite with serrated plates. Telson 1.5 times as long as last abdominal somite; 1.6 times as long as wide anteriorly and 0.4 times as wide posteriorly as anteriorly. Telson cleft with 16 to 23 spinules (34 in type locality), occupying entire cleft. Cleft acute angular, 0.2 of telson length. Lateral margins of telson with 8 to 15 spiniform setae, occupying posterior half of telson, among them terminal spiniform seta shorter than subterminal.

Eyes 1.1 times as long as wide, slightly flattened dorsoventrally. Eye length 0.5 of anterior head width. Cornea narrower than stalk (0.8 times as long as stalk) and 0.4 times as long as eye entire length.

Antennular peduncle segment 3, distomedial margin with two long simple setae. Antennal scale reaching half of segment 3 of antennal and antennular peduncles, 2.0 times as long as wide. Labrum apically pointed, without spine. Mouthparts and maxillipeds typical for the genus (as illustrated earlier in Daneliya, 2012). Maxilla 1 with four posterior setae.

Exopod of thoracopods, basal segment outer margin apically rounded; exopod 1 and 8 are 8-segmented, the rest 9-segmented. Pereopod 1 endopod. Ischium rather broad, almost triangular, 0.5 times as long as merus; its medial margin serrated, with seta at each notch of crenulation, with seven teeth. Merus with medial concavity, bearing antero- and posteromedial margins serrated, also with seta in notches of crenulations. Carpopropodus strongly inflated, 1.9 times as long as wide, as long as merus and 2.0 times as wide as merus, with four short strong distomedial spiniform setae, roughly serrated anteriorly, and three or four medial strong spiniform setae, distally finely serrated and with curved tips. Unguis long, semilunar, but not meandering, 0.7 times as long as carpopropodus.

signs indicate former records); (B) distribution in the Tasman Sea.

Pereopod 2 endopod. Ischium rather short, 0.6 times as long as merus, without bending between ischium and merus. Merus with seven medial groups of one to three setae. Carpopropodus 7−8-segmented (5−6-segmented in Coral Sea); segments prolonged; segment 1 almost as long as segments 2−4 combined. Dactylus longer than dactylus of pereopods 4−6, with strong unguis. Pereopod 3−6 endopods. Preischium with one seta. Ischium rather long, 1.7−1.9 times as long as merus; ischium and merus forming angle. Merus 2.9−3.6 times as long as wide, with five medial bunches of setae. Carpopropodus 5−6-segmented (4-segmented in the Coral Sea); segment 1 shorter than segments 2 and 3 combined; segments 2−5 about as long as wide; segment 6 slightly longer than wide. Paradactylary setae smooth. Dactylus rather short, 0.5 as long as last segment of carpopropodus, with strong unguis, 2.3 times as long as dactylus. Penis tubular.

Pleopods similar in male and female with seven to nine the specimens from the Tasman Sea, without illustrating them long setae. Uropod exopod slightly shorter than endopod. (apart from the color Fig. 16 ). I provide a revised diagnosis Endopod inner margin with 9 to 12 spiniform setae. of H. (G.) harpaxoides , based on a comparison with the other species in the subgenus.

Color. Similar to that in Lizard Island specimens in the Coral Sea ( Daneliya, 2012): cephalic part of carapace snow white; thoracic part of carapace from pleurocervical fissures Heteromysis (Olivemysis) Băcescu, 1968 to the posterior margin blood red; eyes with dorsal red stripe; Heteromysis (Olivemysis) Băcescu, 1968: 237 .—Bowman cornea black; abdomen and appendages not pigmented & Orsi, 1992: 739.— Bravo & Murano, 1996: 483.— ( Fig. 16 ). The coloration is similar to the color pattern of Wittmann, 2000: 287; 2001: 104; 2008: 368, 370, the cuticular spines of the hermit crab Dardanus megistos 371; 2013a: 505.— Wittmann & Chevaldonné, 2016: (Herbst, 1804). This was first noticed by Martin (2012). I 7.— Wittmann & Wirtz, 2017: 145, 148.—Wittmann & can confirm the color similarity based on both the Coral Sea Griffiths, 2017: 40.— Wittmann & Abed-Navandi, 2019: ( Daneliya, 2012) and the Tasman Sea material, where the 81, 82, 93; 2021: 136−138.— Lowry & Stoddart, 2003: collection specimens have been life-photographed, though 448 (spelling correction).— Price & Heard, 2008: 143; the actual mimicry still has to be documented. 2011: 33, 43, 44.— Price et al., 2018: 2, 8.— Daneliya, 2012: 135, 136, 141, 146, 147.— Hanamura et al., 2012:

Variation. I previously noted variation in the telson 17.— San Vicente & Monniot, 2014: 340. characters ( Daneliya, 2012), and the new material from the Heteromysis (Olivaemysis) .— Băcescu, 1970: 11, 14, 16.— Tasman Sea broadened our knowledge. Particularly, the Băcescu, 1979: 143.— Băcescu, 1983: 6, 8, 11.—Băcescu number of the telson lateral spiniform setae vary from 8 to & Iliffe, 1986: 99, 100, 102.— Bamber, 2000a: 133.— Hanamura & Kase, 2001a: 17. Unjustified emendation.

16 (no longer geographically significant); the telson cleft with 15 to 23 spinules (34 in the type locality); the pereopod Type species. Heteromysis rubrocincta Băcescu, 1968 , by 2 carpopropodus is 7−8-segmented (4−6-segmented in monotypy. the Coral Sea); the pereopod 3−6 carpopropodus is 4−6- segmented (no geographic discrimination); the uropodal Diagnosis. Eyestalk with acute distomedial spine (spines) or endopod with 9 to 14 spiniform setae (not significant tubercle in most of species; cornea slightly narrower or rarely geographically). about as wide as stalk. Male sternites with medial process. Antennular peduncle segment 3 with two distomedial

Distribution. Coral Sea, Australia: Great Barrier Reef, flagellated spiniform setae: one directed anteriorly, shorter Wistari Reef ( Băcescu & Bruce, 1980; type locality), Heron and thicker than another, directed laterally, seta. Ischium of Island, Lizard Island ( Daneliya, 2012), Middleton Reef (this pereopod 1 endopod about 1.5−2.5 times as long as wide; study). Eastern Indian Ocean, Australia: Ashmore Reef medially without denticles (only setae on slight tubercles). ( Murano, 1988); Dampier Archipelago ( Hanamura, 2007). Merus of pereopod 1 endopod without distomedial process; Tasman Sea (all in this study, first records from New South its medial margin without flagellated spiniform setae, and Wales): Port Kembla Harbour and south of Baronda Head lateral margin with barbed or serrated setae (this character (southern NSW) ( Fig. 17 ). Firstly recorded in the Tasman Sea still requires confirmation for some species). Carpopropodus and off New South Wales coast of Australia. The specimen of pereopod 1 moderate in size, shorter than merus (or from near Baronda Head is the southernmost record of the occasionally as long as merus), with medial flagellated species. spiniform setae and without long and serrated paradactylary setae. Penis narrowing apically, with thin finger-like lobes.

Habitat. Sublittoral species, found at depths of 0.5−15 m; Male pleopods modified, with flagellated spiniform setae.

commensal on hermit crab D. megistos (Băcescu & Uropodal endopod shorter than exopod.

Bruce, 1980; Murano, 1988; Western Australian Museum Collections, 2020), but also under rocks, in rubble, algae Comparison. The subgenus Olivemysis is characterized and other sediment on the surface of reefs ( Daneliya, 2012). by rather the unique structure of the eyes, the pereopodal In the Tasman Sea, found inside clam shells and other hard endopods, especially pereopod 1, and the armature of the substrate, confirming facultative nature of its commensalism, male pleopods. However, certain species may lack one of already noted in the Coral Sea ( Daneliya, 2012). the characters. The eyes are typically conical with the cornea slightly narrower than the stalk, though in some species

Life history. There was no confirmed species identification, the cornea can be about as wide as the stalk; and the stalk

but according to preliminary reports ( Martin, 2012), H. (G.) typically having a strong acute distomedial spine, directed

harpaxoides may form families, living in association with D. laterally, but occasionally absent or represented instead

megistos , and the body coloration of mysids may correspond either by a tubercle or even by two spines in one species.

to the coloration of cuticular spines of the hermit crab. The pereopodal endopod 1 has rather wide and relatively

Remarks. Heteromysis (G.) harpaxoides was originally short carpopropodus, lacking the strong paradactylary described well in detail by Băcescu & Bruce (1980) from the setae. The carpopropodus segment 1 is usually about Coral Sea. Eight years later, Murano (1988) reported it from twice as long as wide, but in a couple of species it is three the Indian Ocean coast off Western Australia. In another nine time as long as wide; it is also normally shorter than the years Hanamura (2007) reported it for the third time, farther merus, but again in one species it is about as long. All the south along the Australian coast, near Dampier Archipelago. species have the modified male pleopods, bearing brush- More recently, I provided illustrations of the species from like set of short flagellated spiniform setae, although a its fourth record, again from the Coral Sea (Daneliya, variety of combinations exist concerning distribution of 2012), including mouthparts and maxillipeds that were not setae among the pleopods and their numbers, and these illustrated originally. Here I limit myself to a description of setae can occasionally be found also in the females. From

Gnathomysis the subgenus Olivemysis also differs by the presence of the flagellated spiniform seta on the antennular peduncle segment 2 and 3, the absence of the serration on the ischium of the pereopod 1 endopod, its carpopropodus being shorter than the merus (longer than the merus in Gnathomysis ), the uropodal endopod shorter than the exopod (slightly longer or about as long in Gnathomysis ). Finally, from Neoheteromysis it is distinguished by the presence of the flagellated spiniform setae on the antennular peduncle segment 2 and 3, the absence of the serrations of the pereopod 1 dactylus (uniquely found in Neoheteromysis ), and the short size of the flagellated setae on the male pleopods (rather long in Neoheteromysis ).

Remarks. The subgenus Olivemysis was described by Băcescu (1968) for the species of Heteromysis with the dimorphic pleopods 4 and sometimes also pleopods 3, and the modified spiniform setae on the antenna 1 peduncle, which he later called “phanerae” ( Băcescu, 1970) or “flagellated spines” ( Băcescu, 1979) or “Olive Tattersall’s spines” ( Băcescu, 1983). He also changed the name spelling into Olivaemysis ( Băcescu, 1970) and described species with the sternal processes, originally considered by him characteristic to Heteromysis s. str. only ( Băcescu, 1968). Brattegard (1969, 1970, 1973, 1974a, b, 1975, 1980) and Modlin (1984, 1987a, b, c) preferred not to use subgeneric names at all, although they dealt with the species, included into Olivemysis . Bowman & Orsi (1992) returned to the original spelling of Olivemysis . Bamber (2000a) used Olivaemysis spelling again, while Wittmann (2000) preferred Olivemysis . Hanamura & Kase (2001a) did not accept the subgenus, and again used Olivaemysis spelling. Fenton in Lowry & Stoddart (2003) was the first to particularly notice the incorrect spelling for the subgenus as Olivaemysis, although previously using it herself ( Fenton, 1986), and revised it. Wittmann (2008) described another species of Olivemysis with the sternal processes and stressed that it is not purely characteristic for the nominotypical subgenus, which was not done by Băcescu (1970). Finally, Wittmann (2008) also stressed that Băcescu’s (1970) emendation of the subgenus name to Olivaemysis was unjustified and thus incorrect according to the Code. Despite considerable work done with the subgenus, its proper diagnosis appeared only in Price & Heard (2011), who included the differentiation of the two distomedial setae, with the flagellated seta directed anteriorly and a simple long seta directed laterally; the distinction of the pereopod 1 endopod, which was moderately robust (“ H. waitei type ” in Băcescu’s [1979] terminology); and the difference in the length of the uropodal rami, where the uropodal endopod was shorter than the exopod. The last modification of the subgeneric definition came with Wittmann & Abed-Navandi (2021). They noted that the antennular flagellated seta (“bifid flagellate spine”, in their terminology) was directed distomedially; the pereopod 1 endopod (“thoracic endopod 3”) was prehensile, which is the tribal character; the absence of serrations and distomedial process (“tooth-like extension”) on the merus, and of the paradactylary setae on the propodus of the pereopod 1 endopod; the eyestalk had distomedial process in form of spine or tubercle in most of the species. The originally described modification in the pleopods 3 and 4 was expanded to include all five pleopods, although a wide variety of combinations exist with the number of the modified pleopods, and the common feature is still the fact of presence of the modifications.

The representatives of the microps -group in the subgenus Heteromysis s. str., as well as the genus Ischiomysis , also have the distomedial flagellated spiniform seta on the antennular peduncle segment 3. In the microps -group it is usually rather long, about as long as the second, laterally directed spiniform seta. In Ischiomysis this seta is as short, but seemingly thinner than in Olivemysis . However, the presence of the flagellated spiniform setae is no longer considered unique for Olivemysis . Nevertheless, as I could see from the current material, both distomedial setae of the antennular peduncle segment 3 are flagellated in Olivemysis as well as in the members of the microps­ group. Taking this and other characters that arise from the comparison of different subgenera into account, I updated the diagnosis of Olivemysis . Referring to the update, I also include more species in the subgenus.

Composition. The subgenus contains 47 species, among which two, H. (O.) abrucei Băcescu, 1979 and H. (O.) murrayae sp. nov. are found in the Tasman Sea. Comparing species from other parts of the world I noticed that the following species must also be included into Olivemysis and are re-classified here into that subgenus; new subgeneric reclassifications: Heteromysis (Olivemysis) bredini Brattegard, 1970 , Heteromysis (O.) brucei O. S. Tattersall, 1961 , Heteromysis (O.) disrupta Brattegard, 1970 , Heteromysis (O.) odontops Walker, 1898 , Heteromysis (O.) waitei W. M. Tattersall, 1927 . Heteromysis thailandica , previously part of Olivemysis , clearly belongs to the nominate subgenus of Heteromysis (see the relevant section above).

Figures

Figure 16. Heteromysis (Gnathomysis) harpaxoides, male, 7.5 mm, Tasman Sea, New South Wales, north of Tathra,AM P.77631. Photographed live by R. T. Springthorpe, Australian Museum.

Figure 17. Distribution of Heteromysis (Gnathomysis) harpaxoides. (A) general distribution (the white