Macropodia czernjawskii (Brandt, 1880)

Spiridonov, Vassily A., Simakova, Ulyana V., Anosov, Sergey E., Zalota, Anna K. & Timofeev, Vitaly A., 2020, Review of Macropodia in the Black Sea supported by molecular barcoding data; with the redescription of the type material, observations on ecology and epibiosis of Macropodia czernjawskii (Brandt, 1880) and notes on other Atlanto-Mediterranean species of Macropodia Leach, 1814 (Crustacea, Decapoda, Inachidae), Zoosystematics and Evolution 96 (2), pp. 609-635 : 609

Macropodia czernjawskii (Brandt, 1880) Figs 2 , 3 , 4 , 5 , 6 , 7 , 8

Stenorhynchus Czernjawskii Brandt, 1880: 399-400.

Stenorhynchus czernjawskii - Spiridonov and Petryashov 2011: 282, fig. 5 (location and status of the type material).

Macropodia czerniavskii (misspelling) - Forest 1964: 348, 351-354; Forest and Zariquiey Álvarez 1964: 230, figs 4, 9, 10, 15; Zariquiey Álvarez 1968: 478 (key), 479, figs 161a, 162d; Noël 1992: 136 (key).

Macropodia czernjawskii - d’Udekem d’Acoz 1992: 129, figs 1-5; d’Udekem d’Acoz 1994: 14; d’Udekem d’Acoz 1999: 199; Ďuriš, Ateş, Özalp and Katağan 2013: 53, fig. 4E, F.

Stenorhynchus longirostris - Czerniavsky 1868: 77 (nec Cancer longirostris Fabricius, 1775).

Macropodia longirostris - Kobjakova and Dolgopolskaya 1969: 289; Makarov 2004: 328, figs 158-160; Marin 2013: 101, pl. 43 fig. 2 (nec Cancer longirostris Fabricius, 1775).

Stenorhynchus aegyptius - Czerniavsky 1884: 127 (nec Stenorhynchus egyptius H. Milne Edwards, 1834).

Macropodia aegyptia - Băcescu 1967: 271, figs 117-119 (nec Stenorhynchus egyptius H. Milne Edwards, 1834).

? Macropodia rostrata - Makarov 2004: 332, figs 161-163 (nec Cancer rostratus Linnaeus, 1766).

Type material.

The type series from the Crimean Peninsula, Black Sea included, as reported by Brandt (1880), six syntypes: four ovigerous females collected by Czerniavsky in Yalta, one male from Sevastopol, collected by Ussov in 1876 and another male collected by Herzenstein and Tatarykov in Sevastopol in 1875. These four females were also listed by Czerniavsky (1884: 129)

The lot of ZIN-RAS 1609 was identified as containing type specimens of the species ( Spiridonov and Petryashov 2011): one male (all pereopods detached, right cheliped present), one separated pereopod of male, one female ovigerous (both chelipeds undetached) in a separate jar; and three female ov (all pereopods detached, one pleon detached) in another jar. The label affixed on the first jar is probably an original label given at registration in the Museum’s collection: " Stenorhynchus czernjawskyi A. Brandt. Sinus Yaltensis. Czernyavskyi, 1869". Inside the jar, there were two additional labels: " Macropodia aegyptia (Milne-Edw.) det. V. Makarov" and " Macropodia longirostris (Fabricius) (= M. aegyptia ), det. Z. Kobjakova". Similar labels (but not the old one) are present in the second jar of the same lot (with three females). The first label is the result of the work with the collection of Vladimir Vladimirovich Makarov, the curator of Decapoda in the ZIN-RAS in the late 1930s and the second one may be clearly attributed to the studies of Zinaida Ivanovna Kobjakova at the time of preparation of the Black Sea Fauna Guide (Kobjakova and Dolgopolskaja 1969).

The year given on the label is not precise, because as mentioned above, at least part of the ovigerous females were collected in 1867. In the later monograph, Czerniavsky (1884: 127) indicated that the females identified as Stenorhynchus longirostris were collected in 1867-1869, although there is no possibility of identifying which of the female syntypes were collected in 1867 and 1869.

The size of the single extant male (TL 17.9 mm, CW 9.0 mm), stored together with the female syntype, does not correspond to the CW of the male syntype collected by Herzenstein and Tatarykov and reported by Brandt (1880: 398) as "junges, nur 8 mm grosses Mänchen”. Brandt did not mention the size of another male syntype collected in Sevastopol by Ussov, but Czerniavsky (1884: 129) indicated that this specimen’s CW was 7.2 mm. He also reported another, presumably male specimen collected together with four ovigerous females, which were described by Brandt (1880) as syntypes. Its CW is 9 mm, thus corresponding to the male from ZIN-RAS 1609. Most probably the male specimen, stored together with one of the female syntypes, was collected by Czerniavsky together with females, but was either not examined or not mentioned by Brandt (1880) in his species description. Thus its status would be better regarded as unclear, although it cannot be excluded that Brandt had seen it when describing Stenorhynchus czernjawskii (a possible syntype). The male syntypes collected by Ussov and Herzenstein and Tatarykov originated from the collection of St. Petersburg University ( Brandt 1880), which was also used for teaching purposes. They were probably returned to the University ( Spiridonov and Petryashov 2011), but to date, we have failed to locate them there.

Taking into account numerous confusions with the identification of Macropodia in the Black Sea and aiming at nomenclature clarity, it is necessary to select a lectotype for Stenorhynchus czernjawskii . Owing to the undoubted syntype status of the females from lot ZIN-RAS 1609 collected in Yalta, we have selected one of them, (the female stored together with the male) as a lectotype for Stenorhynchus czernjawskii ; its new catalogue number is ZIN-RAS 88751. The remaining three females, collected in Yalta, thus become paralectotypes retaining the catalogue number ZIN-RAS 1609. The male from this lot with a status of possible paralectotype, or at least a specimen collected in a topotypic locality synchronously with the type series, has received a new catalogue number ZIN-RAS 88750. The present interpretation of this specimen’s status is different from that given by Spiridonov and Petryashov (2011) who regarded it as an undoubted syntype.

Other material.

Black Sea. 1 female; Crimean Peninsula; Feodosia; 3-4 fathoms (about 6 m); OF Retovsky leg; ZIN-RAS 35099. 2 males; of Crimean Peninsula; RV “Meotida”, Stat 41; 1909; SA Zernov leg; ZIN-RAS 35102. 1 male; Crimean Peninsula, of Laspi; 44°29.30'N, 33°28.14'E; 3-5 m depth, in algae; SCUBA; 17.07.2009; SE Anosov leg; ZMMU Ma3543. 1 female ovigerous; Crimean Peninsula, of Laspi; 44°29.30'N, 33°28.10'E; 1-2 m depth, in macrophytes; snorkelling; 18.08.2009; SE Anosov leg; ZMMU Ma3546. 1 female ovigerous; Crimean Peninsula, Sevastopol, Kruglaya (Omega) Cove; 44°36.07'N, 33°26.50'E; 2011; SE Anosov leg; ZMMU Ma3542. 1 male; Crimean Peninsula, Sevastopol, Cape Vinogradnyi; 44°31.01'N, 33°28.14'E; 5-6 m depth, sand, detached algae; SCUBA; September 2014; SE Anosov leg; ZMMU Ma3544. 1 female ovigerous; Crimean Peninsula, Sevastopol; 2016; VA Timofeev leg; ZMMU Ma3550. 1 female; Crimean Peninsula, Sevastopol, Kruglaya (Omega) Cove; 44°36.10'N, 33°26.50'E; 08.10'; 2017; VA Timofeev leg; ZMMU Ma3551. 1 female ovigerous; Crimean Peninsula, Sevastopol, Kazachia Cove; 44°34.50'N, 33°24.80'E; 0.5 m depth, in algal meadow; hand collecting; 23.05.2018; VA Timofeev leg; ZMMU Ma3611. 1 male; Crimean Peninsula, Liman Donuzlav; 45°20.70'N, 32°58.30'E; 1 m depth, snorkelling; 15.06.2018; VA Timofeev leg; ZMMU Ma3610. 1 female ovigerous; Cis-Caucasian Coast, east of Zheleznyi Rog Cape; 45°06.18'N, 36°45.39'E; 2-3 m depth, mergel reefs with sparse macrophyte growth; SCUBA, 08.08.2012, VA Spiridonov leg; ZMMU Ma3538. 2 males, 3 females ovigerous; Cis-Caucasian Coast, near Blagoveschenskaya, in vicinity of Anapa; 45°02.16'N, 37°05.18'E; sand, 2-3 m depth, from fouling on sunken ropes and on sand (male); snorkelling; June 2013; SE Anosov and AK Zalota leg; ZMMU Ma3547. 1 male; Cis-Caucasian Coast, off Inal; RV “Ashamba” Stat 7, 44°19.729'N, 38°36.887'E; 9-12.8 m depth, sand, shell, macrobenthos dominated by Chamellea gallina , Diogenes pugilator and Rapana venosa ; dredge; 02.07.2015, 15:02-15:20; GA Kolyuchkina, AA Vedenin, V Kokarev and AB Basin leg; ZMMU Ma 3545.1 male Cis-Caucasian coast, nature reserve Utrish; 44°44.645'N, 37°24.491'E; transect 1; 6-8 m depth, gravel and pebble, SCUBA, 28.07.2018; UV Simakova leg; ZMMU Ma3615. 1 male; Cis-Caucasian coast, Golubaya Cove, near Gelendzhik; 44°34.5'N, 37°58.7'E; 2-3 m depth, walking on sand, patches of Zostera noltei , algae, snorkelling, August 2008, GA Kolyuchkina and UV Simakova leg, ZMMU Ma3548. 1 male; Cis-Caucasian coast, Tuaphat, near Gelndzhik; 44°34.5'N, 37°56.6'E; 2.5 m depth, rock, shell, Cystoseira patch; snorkelling; September 2010; SE Anosov leg; ZMMU Ma3549. 1 male; Trans-Caucasian coast, Abkhazia, Sukhum, in front of boulevard; 4-8 m depth, in Cystoseira ; Sigsbee trawl; 31.07.1908; K Yagodovsky leg; ZIN-RAS 35101. 1 female; 1 male; Black Sea; RV "Ledokol # 1", Stat 38; SA Zernov’s Expedition leg; ZIN-RAS 35096. 1 female; Black Sea; vessel not indicated; Stat 4, 1914; AN Derzhavin leg; ZIN-RAS 35097.1 female; Black Sea; RV “Gaidamak”, Stat 19, August 1911; SA Zernov leg; ZI N-RAS 35100.

Mediterranean. 2 males; Aegean Sea, Crete; Cruiser “Bogatyr”; Bachinsky leg; ZIN-RAS 35098. 1 female; Aegean Sea, Greece, Gulf of Euvaia, 10.06.1971; A Koukouras leg; SMF 7442. 1 male; Aegean Sea, Greece, Kyra; 39°18.40'N, 24°03'E; 6-8 m depth, 01.07.1978; M Türkay leg; SMF 12700. 1 male; Adriatic Sea, Croatia, 6 km south of Rovinj, Dvije Sestice; 32 m depth; dredge; 10.09.1985; Frankfurt University Excursion leg; SMF 13979. 1 female; Adriatic Sea, Croatia, Istria, Bale Dudit, south of Cape Guobinja; 4 m depth; August 1982; Pettke leg; SMF 14055.

Diagnosis.

Cephalothorax, pleon and thoracopods densely and unevenly setose. Rostral spines covered with large curled setae, moderately ascending, slightly convex to straight in lateral view, somewhat over-reaching (in males), reaching or nearly reaching end of antennal peduncle, usually about as long as 30% of total carapace length in females and about 35% in males. Epistome trapezoidal with two conspicuous lateral spinules on each side. All carapace protuberances, spines and tubercles setose. Gastric region with a pair of lateral protogastric protuberances or spines, a pair of mesogastric tubercles and robust median metagastric spine of moderate height, directed slightly anteriorly or straight dorsally. Two conspicuous hepatic protuberances on each side, lower being most robust. Pterygostomial process seen dorsally in males, but barely in females. Cardiac region elevated, with strong median obtuse spine directed slightly posteriorly. Intestinal region with median spiniform tubercle at border with cardiac region. Basal antennal segment with three (in some specimens two or four) spines. Merus of P 2-5 with a distal dorsal spine. Dactyli of P 4 and 5 little narrower than propodi, markedly curved (sickle-shaped), with a dense row of robust sharp spinules located on flexor margin, along with setae; adductor face with few setae and mostly naked.

Description.

Females. Cephalothorax pyriform, elongated in anterior part. Postrostral carapace length to maximum width ratio from 1.2 to 1.4. Carapace surface, sternal area, pleon and chelipeds unevenly and densely covered with pile. Regions well defined. Rostral horns straight to slightly convex (lectotype), closely set together reaching or hardly reaching end of antennal peduncle, as long as 20-34% of total carapace length. Ten - fifteen conspicuous hooked, curled and coiled (ansiform) setae on each dorsolateral margin. Dorsal orbital eave well-expressed, markedly elevated over frontal region (Figs 2 ; 5d-c ).

Region between eave and hepatic region broader than basis of rostrum, anterolateral angles of buccal cavity are not seen dorsally. Epistome trapezoidal with two conspicuous lateral spinules on each side. Pair of tubercles mesially of posterior spinules at buccal margin. Anterior margin of buccal cavity costate, broadly V-shaped medially, anterolateral corners as broad quasitriangular lobes directed ventrally, visible in dorsal view (Figs 2b ; 7a, b ).

Gastric region with large protogastric protuberance on each lateral side. Two closely set median gastric tubercles, located slightly anteriorly to lateral gastric protuberances. Metagastric median spine (directed slightly anteriorly or straight dorsally) robust, obtuse. Hepatic region with two closely-set robust lateral protuberances, lower one largest, ending in bunch of straight setae (obsolete in lectotype). Pterygostomial region with shorter ventrolateral spine located ventrally just anterior to cervical groove; usually barely seen dorsally. Branchyal region with obtuse posterior spine (protuberance), standing approximately at mid-distance from posterior margin to cervical groove and two obtuse upper protuberances located along urogastric region. One or two spinules at posterolateral face. Cardiac region elevated, with low, obtuse, robust median spine directed slightly posteriorly. A median spiniform tubercle may be present at border between cardiac and intestinal regions. Large spiniform tubercle or protuberance at each metabranchial region. Spinules may be present at posterior carapace margin anterior to coxae of last pereopods (Fig. 2 ). All large spines, protuberances and tubercles end in sparse bunch of setae (obsolete in lectotype).

Thoracic sternum with indistinct sutures, with two lateral depressions in anterior part, separated by setose ridge-like elevation. Margins of 4th sternite and episternites 5-7 form a ridge bordering sterno-abdominal cavity (Fig. 2b ).

Eyestalks relatively robust, directed perpendicular to orbital eave, with distal doubled setae dorsally. Cornea occupying about 1/5 of eyestalk.

Antennular fossae elongated, occupying most of the ventral part of frontal region of carapace; posterior margin of each fossa with a spinule. Interseptum between fossae bears a pronounced quasitriangular tooth (Fig. 3 с). Antennules folded longitudinally, basal segment of antennule with sublongitudinal row of spinules (in lectotype, two on right antennules and three on left one), reaches to anterior tooth on lateral margin. Second segment reaches to about 7/8 of fossae extension.

Basal antennal segment extends along margin of antennular fossum, fixed in proximal half, distally free, reaching to anterior margin of antenullar fossae; with three spines on ventral face of fixed part, directed anterolaterally and visible not only in ventral but in lateral view, posterior spine usually smallest (Figs 2b, c ; 3c ; 6a, b ). Spine on distoventral margin, near articulation with 2nd article, 2nd article about as long as free part of basal article; 3rd article long, hardly reaching the tip of rostral spine, with sparse setae along length and a fan of setae directed mesially and anteriorly. Antennal flagellum reaching to about tip of cheliped extended anteriorly; with sparse setae of different size.

Maxiliped 3: ischium of endopod relatively narrow, medially convex, postero-mesial end deflected; with row of three spinules along lateral margin on external face, another row of three spinules and sparse setae close to mesial margin interspaced by scattered strong setae. These rows, consisting of two or three spinules each, continue in merus. Merus prismatic, narrower than ischium, nearly as broad in dorso-vental dimension as in mesio-lateral one, with rounded anterior margin and strong directed forward spinule at antero-lateral angle, smaller spinule subdistally on lateral margin may be present; strong sparse setae at mesial corner. Carpus little shorter than merus, markedly broadening mesially, with concave smooth extensor face and convex setose flexor face; a small spinule at antero-lateral corner. Propodus little shorter than carpus, with densely setose flexor face; dactylus narrow, nearly as long as carpus, setose on margins.

Cheliped homoiochelic, markedly setose. Coxa and basis short, massive; ischium prismatic, with rows of 4 sharp spines margin of flattened flexor face; a strong distal spine at extensor face. Merus prismatic, with rows of 5-7 spines along flattened margins, being continuations of respective rows of ischium. Another row of 6-7 spines along mesial face; strong distal dorsal spine; extensor margin with a row of 3-4 tubercles ending in seta and a long distal setose spine. Carpus with flat flexor face, bearing a stong setose proximal spine and irregular rows of 2-3 spines along its margins, few spines in mid-part may be present; extensor face convex, tuberculate, setose, with one proximal and two distal setose spines or large tubercles (Fig. 2b, c ). Chela with 3-5 sharp small spinules along upper face and a row of minute spinules along lower face. No molariform tooth present at proximal part of dactylus cutting edge; cutting edges with numerous small sharp papiliform teeth.

Post-cheliped pereopods long, P 2 longest, about 1.25 times as long as cheliped and about 1.5 times as long as P 5, which is the shortest of pereopods. In P 2 and P 3, the merus comprises about third of leg length, with distal sharp spine at extensor face, followed by propodus; dactylus over half of propodus length, thin, mostly straight, slightly curved distally, with long setae (Fig. 5c, d ). In P 4 and P 5, the merus comprises over third of leg length, about as long as postrostral carapace length, with distal spine at extensor face; dactylus not much narrower than propodus, curved (sickle-shaped), with a dense row of strong spinules, exceeding length of setae along flexor margin; adductor margin with sparse setae or naked.

Pleon as broad as carapace. Each tergum with a median protuberance. Terga relatively densely covered with rounded granules terminating in short curled setae and numerous spinules laterally (Figs 2b, c ; 5d ). Genital opening slit-shaped, with rounded cap (Fig. 6d ).

Males (only characters different from females). Cephalothorax pyriform, seemingly more elongated than in females in anterior part. Carapace surface, sternal area, pleon and chelipeds less densely covered with pile and setae than in females. Postrostral length to maximum width ratio ranges from 1.3 to 1.5 (Figs 3a, b ; 4d ; 5a, b ).

Rostral spines slightly convex to straight in lateral view, closely set together, with narrow slit, slightly diverging in distal part or touching one another over entire length (Figs 3a, b ; 4c, d ); somewhat over-reaching (as in largest-studied specimens; Fig. 3a ) or reaching end of antennal peduncle, as long as 20-37% of total carapace length (Fig. 4c, d ). Seven to nine large curled setae located on each side of their dorsolateral margins; 7-15 thin moderately-curved to straight setae irregularly placed on dorsal face. Short setae on ventral face. Dorsal orbital eave less pronounced than in females, setose (Figs 3a, b ; 4c, d ).

Gastric region with pair of mesogastric tubercles, which may bear few straight setae; and a pair of spiny protogastric protuberances (directed slightly anterolaterally) and acute and less robust than in females metagastric spine (directed dorsally or slightly posteriorly), with bunch of straight setae (Figs 3a, b ; 4c, d ). Cardiac region elevated, with relatively sharp (compared to females) median spine, smaller than posterior gastric spine (Fig. 3b ).

Thoracic sternum with lateral concavities, separated by median ridge, pair of spiniform tubercle with bunches of setae mesially on 4th sternites. Suture of thoracic sternum with 5th sternite indistinct. Episternites fused with sternites. Sternites 5-7 each with scattered granules and a spinule holding lateral position compared to spiniform tubercles on 4th sternite. Sutures between sternites 5 and 6 interrupted, between other posterior sternites well developed.

Chela setose; dorsal face with row of 4-5 spines of varying spines, similar row along midline of inner face, a row of 6-8 spinules on lower face, continuing to lower face of dactylus (Figs 4a, b ; 7a ).

Chela fingers about 40% of chela length, curved inside, covered with setae mostly on mesial face. Pollex of morphometrically mature male with proximal quadrate tooth; similar tooth at occlusive edge of dactylus; in closed chela, its posterior margin touching anterior margin of first tooth; distally of them, finger edges form a broad gap, contacting each other in distal-most third; small serial papilliform teeth on both finger cutting edges in this contact zone (Fig. 7a ).

Pleon with locking mechanism comprising of button at proximal part of sternite 5 and sockets at antero-lateral angles of pleomere 6. All pleomeres separated, each of terga 4-6 with large median tubercle and pair of small lateral tubercles on both sides; telson semi-oval.

Gonopod 1 relatively slender, mostly straight, with short r-shaped distal tip, aperture opens anteriorly (Fig. 8a, b ). Gonopod 2 very short. Penis in canal formed by posterior lobe of sternite and groove.

Variation.

Variable characters include relative length of rostral spines, which slightly exceeds antennal peduncle in the largest males (Fig. 3a ), usually reaching the distal margin of the peduncle in other males (Fig. 5d ) and usually only approaching it in females (Fig. 2c ). Tubercles, located mesially of the posterior spinules bordering epistome, may be obsolete in females. In the Black Sea specimens, the two mesogastric median tubercles are, in most cases, separate, but may be reduced. On the basis of examination of the specimens from the Western Mediterranean, Zariquiey Álvarez (1968: 478, fig. 161a) reported them to be fused; this condition was also confirmed by Ďuriš et al. (2013) for a specimen from the southern Dardanelles. D’Udekem d’Acoz (1992) reported specimens with separated tubercles from both southern Portugal and the Aegean Sea. The specimens from the Mediterranean, studied by us, have these tubercles closely set, reduced and, in one case, fused. The number of spines of the basal antennal segment is also variable. The Black Sea specimens usually have three spines, in small specimens (i.e. ZMMU Ma 3547) only two can be recognisable. The female from Sevastopol (CW 7.0 mm, ZMMU Ma 3611) has four strong spines on the left basal antennal segment and five spines (with a small posterior one) on the right segment. It also possesses a spine on the 2nd antennal segment. The Mediterranean specimens frequently possess four spines, two of them being large and the other two interspaced with them ( Zariquiey Álvarez 1968; Ďuriš et al. 2013). Most geographical variation reported so far is related to less-developed spines and protuberances on the carapace, the basal antennal segment in the specimens from Portugal’s coast ( d’Udekem d’Acoz 1992: figs 1a; 2a; 3a-c) compared to the Mediterranean and the Black Sea specimens.

In the male (ZMMU Ma3543), chela fingers are not opposed, but strongly crossed (Fig. 7c ) and this may be an apparent abnormality of development or a result of a traumatic event.

Size, chela morphometry and reproductive characteristics.

The female lectotype measures 13.0 mm (TL) and 7.0 mm (CW). The ovigerous female paralectotypes measure 8.0 and 8.5 mm (CW); the 4th paralectotype is damaged and not measured. Non-ovigerous female: CW 5.8 mm (Black Sea). Ovigerous females CW: 5.7-9.0 mm (Black Sea); 4.5-7.5 mm (Mediterranean). Males CW 4.0-8.5 mm (Black Sea), 6.3-6.5 mm (Mediterranean). The maximum TL of the Black Sea and the Mediterranean specimens does not exceed 15 mm which is distinctly less than the TL of the specimens from Portugal, 23.5 mm ( d’Udekem d’Acoz 1992).

Males with CW equal to and greater than 5.0 mm (with the molariform tooth) have, respectively, larger chela than females (Fig. 9a ). The chela morphometrics of the smallest male (CW = 4.0 mm) are closer (within 95% confidence limit) to the values predicted from the regression lines calculated for females rather than those for males (Fig. 9a ; Table 2 ). Although regression coefficients between some chela measurements and CW in females were not particularly high, while in males, correlation coefficients between chela morphometrics and crab size were statistically non-significant (Table 2 ).

Five of the eight studied ovigerous females from the Black Sea, collected in the late spring to summer (from May to August in the years from 2009 to 2016) had eggs at the I stage of embryonic development; one female had eggs at stage II, one at stage IV and the largest female (CW 9.0 mm) had a clutch at the latest stage V in June 2013. The latter clutch was also the largest one of those observed and consisted of 1239 developing embryos while the other females carried from 351 to 986 eggs (see dataset in Spiridonov et al. 2020). There was a weak and statistically non-significant positive correlation between the female size (CW) and the number of eggs at embryonic development stages I-II (Fig. 9b ). Egg diameter at embryonic development stages I and II ranged from 0.371 to 0.537 mm (mean 0.45 + 0.03 mm; n = 6) showed a weak negative correlation with the female size (r = - 0.385, t = - 0.834, p = 0.451). The volume of eggs at these stage averaged 0.051 + 0.0093 mm3.

Colouration.

Mimicking substrate and algae: carapace with whitish pattern on greenish background, legs greyish, with irregular whitish transverse bands (Fig. 5 ).

Ecology and epibiosis.

In the Black Sea, the species was recorded between 0.5 and 9-12.8 m depth, but mostly within the upper 5-6 m on various substrates from rock and boulders to sand (Fig. 10e, f ), in growing or detached aquatic vegetation, i.e. Ulva sp., filamentous green algae, Cystoseira sp., red algae (Fig. 10d ). One male was also recorded in a community dominated by clams Chamelea gallina (Linnaeus, 1758), hermit crabs Diogenes pugilator (Roux, 1829) and predatory whelks Rapana venosa (Valenciennes, 1846) at about 10 m depth, where macrophyte vegetation is generally lacking, according to the underwater observations by the authors. It is very difficult to spot the crabs when they are hiding in algae (Fig. 10a ). However, the males (but not females) were repeatedly observed walking on bare substrate, although a short distance from shelters and being decorated with pieces of algae (Fig. 10c ).

Practically all crabs examined shortly after the collection and preservation in 2008-2018 had significant epibiosis. In some females, i.e. (ZMMU Ma 3538 and 3546), organisms of epibiosis covered 100% of the dorsal carapace surface and most of their legs. Males were seemingly less decorated, with significant area of the carapace and pereopods without epibiosis.

The bulk of epibiosis consisted of algae and cyanobacteria. In twelve carefully examined specimens, 25 autotrophic eukaryote taxa were found, identified to the lowest possible level (see dataset in Spiridonov et al. 2020). Green algae Cladophora sp. and calcareous Corallinales gen. sp. were most commonly recorded (in 50% of specimens). They were followed by phaeophytes Pilayella cf. littoralis , Sphacelaria cirrosa (Roth) C. Agardh and rhodophytes Ceramium siliquosum ( Kützing) Maggs and Hommersand and Asterocytis sp. Of particular interest is the finding of the non-indigenous red alga Bonnemaisonia hamifera Hariot, which was first officially recorded at the Caucasian coast of the Black Sea in 2015 ( Simakova and Smirnov 2017). The present record, however, indicated that the male of M. czernjawskii (ZMMu Ma 3542) carried this introduced species in Crimea as far back as in 2011.

Sessile animals were not as diverse and abundant as the autotrophic taxa. They included unidentified (in poor condition) hydroids and sponges, sedentary polychaets Janua pagenstecheri (Quatrefages, 1865) ( Spirorbidae ; in two cases, on the ventral side) and, in one case, a colony of the bryozoan Lepralia sp. Remains of a similar bryozoan colony were also found in the material from the old collection (ZIN-RAS 35099, Crimean Peninsula, about 6 m depth) (Fig. 4d ).

Habitats recorded outside the Black Sea include the following: upper subtidal, rock with algae, seagrass in the Eastern Mediterranean ( d’Udekem d’Acoz 1994); in Zostera and Cymodocea meadows ( števćić 1990, 1993) and colonies of athecate hydroids Eumendrium racemosum (Gmelin, 1791) in the Adriatic ( Martinelli et al. 2008a); rock, Posidonia oceanica (L.) meadows in Sicily’s waters (Pipitone and Arcuelo 2003); between 10 and 30 m depth, ( Zariquiey Álvarez 1968) or up to 80 m depth ( Forest and Zariquiey Álvarez 1964); on muddy gravel and hard substrates ( Grimes et al. 2016), between 2 and 9 m depth in Posidonia oceanica (L.) beds ( García Raso 1990; Mateo-Ramírez et al. 2016) in the Western Mediterranean; in Caulerpa meadows on sand and clay at 1-3.3 m depth in Cadíz Bay ( López de la Rosa et al. 2006); and intertidal, in sea grass in Portugal ( d’Udekem d’Acoz 1992). Ďuriš et al. (2013) reported the species at 6 m depth from Posidonia leaf surrounded by the tentacles of the sea anemone Anemonia viridis ( Forsskål, 1775). They considered this association accidental.

Distribution.

Black Sea. Crimean coast: Donuzlav lagoon, Sevastopol, Yalta (type locality) ( Czerniavsky 1868, 1884; Brandt 1880; this study); Cis-Caucasian coast (this study), Trans-Caucasian coast in Abkhazia (this study), North-western coast ( Băcescu 1967; Micu and Micu 2006).

Mediterranean: Dardanelles ( Ďuriš et al. 2013); Aegean Sea ( Koukouras et al. 1992; d’Udekem d’Acoz 1994); Levantine Sea ( Shiber 1981); Italian coast ( Martinelli et al. 2008a) and Istria ( Števćić 1990) in Adriatic Sea, Iberian coast, Alboran Sea ( García Raso 1990; Mateo-Ramírez et al. 2016), Arzew and Bou Ismail Bays at Algerian coast ( Grimes et al. 2016).

North-East Atlantic: inner Bay of Cádiz ( López de la Rosa et al. 2006; Marco-Herrero et al. 2012); southern Portugal ( d’Udekem d’Acoz 1992).

Remarks.

In the time when the presence of Macropodia czernjawskii in the Black Sea was neglected by researchers from its coastal countries, the descriptions and illustrations of Macropodia species from this region were published in three regional monographs of Decapoda ( Băcescu 1967; Kobjakova and Dolgopolskaya 1969; Makarov 2004). It was also treated under the incorrect name Macropodia longirostris by Marin (2013) in his atlas of Russian decapods. Two decades ago, Băcescu’s (1967) record of Macropodia aegyptia was recognised to be M. czernjawskii by d’Udekem d’Acoz (1992, 1999) and the species was listed in the Romanian fauna by Micu and Micu (2006). As it follows from the labels of the type material in ZIN-RAS (see above), Kobjakova and Dolgopolskaya (1969) saw the types and probably other specimens of M. czernjawskii in the ZIN-RAS collection (which in reality does not include any specimens of M. longirostris ) when they were preparing their account. However, they treated this material as M. longirostris . The illustration of adult M. longirostris by Makarov (2004: fig. 158) is of insufficient quality. However, some details (dactyli of P 4 and P 5, lateral view) on the figure allow us to recognise M. czernjawskii rather than M. longirostris .

The identity of Macropodia rostrata in Makarov’s (2004) monograph remains problematic. The illustration of an adult specimen ( Makarov 2004: fig. 161) is difficult to attribute to any species of the genus, although the dactylus of P 5 points to M. czernjawskii rather than to M. rostrata . The illustrations of larvae of the two presumed Macropodia species presented by Makarov (2004: figs 159-160, 162-163) do not show any principal differences between these “species”; however, the description does not allow any consistent comparison. Some characters (dorsal spine of carapace, antennal protopod tip) of zoea 1 and 2 of both “species” illustrated by Makarov (2004) are more similar to the respective stages of M. czernjawskii , described by Marco-Herrero et al. (2012). However, these larvae ( Makarov 2004: figs 159, 162) have lateral spines on the telson, which were not observed in the zoea of M. czernjawskii from the Cadíz area ( Marco-Herrero et al. 2012: fig. 7A, B).

Figures

Figure 2. Macropodia czernjawskii (Brandt, 1880), female lectotype (ZIN-RAS 88751). a. Dorsal view. b. Ventral view. c. Lateral view. Scale bar: 5 mm.

Figure 3. Comparison of Macropodia czernjawskii (a-d. possible paralectotype, male, ZIN-RAS 88750) to Macropodia tenuirostris (Leach, 1814) (a' - d'. male, SMF 3749) and Macropodia rostrata (Linnaeus, 1761) (a' ' - d' '. SMF 40660). a. Dorsal view. b. Lateral view. c. Anterior part of the body, with antennules, basal antennal segments, and epistome, ventral view. d. Dactylus of pereopod 5. Scale bars: 10 mm (a-a' ' - b-b ''), 1 mm (c-c' ' - d-d '').

Figure 4. Macropodia czernjawskii (a, b. possible paralectotype ZIN-RAS 1609; c, d. ZIN-RAS 35102) and Macropodia longirostris (JC Fabricius, 1775) (e. SMF 3752). a. Right cheliped, ventral view. b. Right cheliped, dorsal view. c. Cphalothorax, dorsal view. d. Cephalothorax, ventral view. e. Cephalothorax, dorsal view. Scale bar: 10 mm.

Figure 5. Macropodia czernjawskii, photographs in natural coloration. a. male (ZMMU Ma 3547), dorsal view. b. Same specimen as a. ventral view. c. female ov (ZMMU Ma 3542), dorsal view. d. Same specimen as c. ventral view. Scale bar: 10 mm. Photographs by SE Anosov.

Figure 6. Macropodia czernjawskii. a. Anterior part of the body with basal antennal segment (ZMMU Ma 3543); b. Anterior part of the body with basal antennal segments, male (ZMMU Ma 3547). c. Male pleon (ZMMU Ma 3547); d. Female sterno-pleonal cavity with exposed genital segment (ZMMU Ma 3538). Scale bar: 1 mm.

Figure 7. Macropodia czernjawskii. a. Right chela, male, CW 11.0 (ZMMU Ma 3547); b. Right chela, male. CW 6.0 mm (ZMMU Ma 3544) c. Malformed right chela, male, CW 8.0 mm (ZMMU Ma 3543); d, e. Same specimen as c. dactylus and propodus of P 5. Scale bars: 1 mm (a-c, e), 0.5 mm (d).

Figure 8. Macropodia czernjawskii. Male (ZMMU Ma 3543), right gonopod. a. Pleonal view. b. Sternal view. Scale bar: 1 mm.

Figure 9. Morphometric relationships and fecundity characteristics of Macropodia czernjawskii. a. Relationships between carapace width (CW) and the geometric mean of chela length, height and thickness (ChGM). b. Relationships between CW and decimal logarithm of the number of developing eggs (I or II stage of development) on pleopods (F). For statistical data see Table 2.

Figure 10. Natural habitats of Macropodiz czernjawskii in the Black Sea. a, b. Male (ZMMU Ma 3549) in Cystoseira sp., on rock, Tuaphat coastal rock masif, near Gelendzhik. c. Male (ZMMU Ma 3547), on sand, of Blagoveschenskaya village, near Anapa. d. Specimen collected of Blagoveschensakya in aquarium, decorated with red algae after few days of keeping. e. A characteristic biotope of M. czernjawskii in Tuaphat. f. Biotope in Kazachya Cove, Crimean Peninsula where M. czernjawskii has been repeatedly observed. Photographs by SE Anosov.