Gammarus morcae Özbek & Aydin 2023, n. sp.
Makaleler > Tam Makale · 2023
Yazarlar: Özbek, Murat, Aydin, Gökhan
Zenodo (CERN European Organization for Nuclear Research), Uluslararası, 2023
Özet
Gammarus morcae n. sp. (Figures 2–10) Material examined: Holotype male, 22.0 mm (ESFM-MALI/21-01), Morca Sinkhole, Anamur District, Mersin Province, Turkey, 01.vii.2021; collected by G. Aydın. Paratypes: 4 females and 5 males (ESFM-MALI/21-02), same data as holotype. Diagnose: Eyeless, unpigmented body covered with numerous simple setae (Figures 2 and 9D), without keel or tubercles. Sexual dimorphism present (males larger than females, females more setose than males, both gnathopods sexually dimorphic). Antenna I is longer than 50% the length of the body; antenna II is about 50% the length of antenna I, gland cone long and straight. Maxilla I inner plate trapezoidal, with 11 plumose setae, outer plate with 11 multitoothed, comb-like spines; palps asymmetric. Mandibular palp article 3 with 1 group of A-setae, 1-2 groups of B-setae, 26-28 D-setae, and 4-5 E-setae; C-setae absent. All the coxal plates and epimeral plates bear numerous simple setae. Gnathopod II larger than gnathopod I; medial palmar spine present, palmar angles of both gnathopods with groups of strong palmar spines; dactyli with 1 seta along outer margin, nails with 1 setule along inner margin. Bases of pereopods V – VII with several setae on the inner and outer surfaces, proximal parts wider than the distal part, outer margin of dactyli of pereopods III–VII with 1 plumose seta. Urosomites with dorsolateral groups of spines. Dorsal and dorsolateral surfaces of the meso- and metasome segments with numerous simple setae. Pleopods I–III with 2 retinacula. Uropods I and II spinose; uropod III exopodite 1.9× longer than protopodite (in males); endopodite longer than 50% length of exopodite. Telson lobes elongated, with 3 or 4 distal spines per lobe. Coxal gills II–VII are stalked, triangular, or sacciform, gill 7 is the smallest. Body length 16.1–19.0 mm (♀♀), 17.2–23.0 mm (♂♂). Etymology: The name of the new species is derived from the name of the type locality (Morca Sinkhole). Description of holotype male: Body unpigmented. Antennal sinus deep. Posterior side of the head with some setae. Eyes are absent (Figure 2). The antenna I (Figures 2 and 3C) is longer than half of the body length, the first peduncle segment bears setae along the dorsal and ventral margin, setae much shorter than the diameter of the first peduncle segment; the second and third peduncle segments bear 3-4 groups of short setae (shorter than the segment where they implanted); the setation on the flagellar segments is weak. The length ratio of peduncular segments is 1:0.7:0.5. Main and accessory flagellum with 41 and 4 articles, respectively; flagellar segments with short simple setae in their distal parts. Aesthetasc-like structures are present on the flagellar segments (see the detail in Figure 3C). Antenna II (Figure 3B) is shorter than the half-length of antenna I (the length ratio is about 1:0.46). Gland cone straight and elongated, reaches the 0.25 length of the fourth peduncular segment. The fourth peduncular segment bears 11 groups of setae that are shorter than the diameter of the segment. The fifth peduncular segment bears 4 and 7 groups of setae along the dorsal and ventral margins, respectively. The setae along the ventral margin are longer than the diameter of the segment. Flagellum with 14 segments and the flagellar segments are not swollen, without flag-like setae. Calceoli is present on the 2nd–7th flagellar segments of antenna II. The lower lip (Figure 4) is without inner lobe and bears numerous small simple setae along the distal margins of both lobes. Upper lip (Figure 4) with numerous minute setules in the distal part. Left mandible (Figure 5) with 5-toothed incisor, lacinia mobilis with 4 dentitions, molar triturative. The first article of palp without setae, the second one with 14 setae. The third segment has 30 D-setae, 5 E-setae, two groups of A- and one group of B-setae. C-setae absent. Right mandible (Figure 5) has 3-toothed incisor and bifurcate lacinia mobilis. Right maxilla I (Figure 6) has 11 plumose setae along the inner margin of the inner lobe in addition to some tiny setules. The outer lobe bears 11 distal stout serrate spines and some tiny setules on the inner margin. Palp of the outer lobe with no seta in the first segment and four stout spines and two simple setae on the distal part of the second segment. The outer margin has no seta. The second article of left palp bears 7 spines and three simple setae on its distal part and no seta along the outer margin. Maxilla II (Figure 7) has a diagonal row of 13 plumose setae in the inner plate and some long simple setae on the distal part of the outer lobe. There are also a few tiny hairs in the proximal part of the inner margin of the lobe. Maxilliped (Figure 7) has 3 tooth-like spines and a spine in the distal part and the distal corner of the inner plate, respectively. Additionally, there are 7 plumose setae along the inner margin of it. Outer plate armed with 7-8 serrate stout setae in the distal part and 16 spines along its inner margin. Coxal plates bear numerous simple setae and it is one of the discriminating characteristics of Gammarus morcae n. sp. Coxal plate I (Figure 3A) is rectangular and bears many setae (~30) on the outer surface of the anterior and ventral sides. Coxal plate II (Figure 3F) is triangular; setation is similar to that of the coxal plate I; bears more setae (~50). Coxal plate III (Figure 8A) is rectangular, and bears several setae (~50) on the outer surface; additionally, 2-3 setae occur on the inner surface. Coxal plate IV (Figure 8B) is longer than its width (l/w ratio is about 1:0.8); has a slightly convex distal margin; covered with many setae (~90). Coxal plates V and VI (Figures 9A and 9B) bilobate. Coxal plate V bears 5 setae on the anterior lobe and many setae (~14) on the posterior lobe. Coxal plate VI (Figure 9B) with no seta on the anterior lobe and some setae (~14) on the posterior lobe. Coxal plate VII (Figure 9C) bears 1 seta along the anterior margin and many setae (~14) on the posterior margin. Gnathopod I (Figure 3A) has 10-12 long simple setae along both margins of the basal segment; the length of the setae can be up to twice the diameter of the basis. In the posterodistal corners of the basis and ischium, a group of short setae exists. The posterior and distal margins of the merus bear many simple setae. Carpus triangular; anterior margin bears four groups of simple setae; posterior margin with 5-6 groups of simple setae. Propodus pyriform, anterior margin with seven groups (3 and 4 groups on inner and outer surfaces, respectively) of simple setae; middistal spine is present; posterodistal corner armed with a strong spine in addition to some small spines. Dactylus reaches the posterodistal corner and bears a simple seta along the outer margin in addition to a small setule around the distal part of the inner margin. Gnathopod II (Figure 3F) bears 4 or 5 long setae along the anterior and posterior margins of the basis in addition to some (9-10) shorter simple setae; the length of the setae can be more than twice the length of the diameter of the segment. Ischium bears a group of short and simple setae at the posterodistal corner. Merus bears a group of simple setae along each margin in addition to many setae at the distal margin. Carpus triangular, three groups of setae present along the anterior margin; posterior margin with 9-10 groups of setae. Propodus armed with 8 groups of short setae along the anterior margin; posterior margin with many groups of setae; medial palmar spine present; posterodistal corner armed with a strong spine in addition to some small spines. Dactylus reaches the posterodistal corner and bears a simple seta along the outer margin in addition to a small setule around the distal part of the inner margin. Pereopod III (Figure 8A) bears two groups of long setae near the proximal part of the anterior margin in addition to 3-4 groups of short simple setae near the distal part; the longer setae are shorter than twice the length of the diameter of the basis; posterior margin more setose, bears 7-8 groups of setae; setae on the proximal part are longer than those on the proximal part; some of them can be more than twice length of the diameter of the segment. Ischium bears a group of short setae at the posterodistal corner. Merus and carpus bear short setae along their posterior margins. The anterior margin of the merus bears 4 groups of short setae while that of the carpus is bald. Propodus with three and five groups of short setae along the anterior and posterior margins, respectively. Dactylus bears a minute plumose seta along the outer margin in addition to two minute simple setae near the distal end of the inner margin. Pereopod IV (Figure 8B) bears 6-7 long and 5-6 short setae along the proximal and distal part of the anterior margin, respectively; setae can be longer than 1.5 times the length of the diameter of the segment; posterior margin more setose, bears 10-11 groups of long setae; some of them can be more than 1.5 times length of the diameter of the segment. Merus and carpus bear short setae along their posterior margins. The anterior margin of the merus bears 4 groups of armaments (each has a spine and a few short setae) while that of the carpus bears 3 groups of armaments. Propodus with five groups of short setae along the anterior and posterior margins. Dactylus bears a minute plumose seta along the outer margin in addition to one minute simple seta near the distal end of the inner margin. Pereopod V (Figure 9A) is slightly elongated. Basis has a setose posterior margin; setae present both on inner and outer margins; anterior margin with 7 groups of armament; length/width ratio of the basis is about 1.3. Ischium bears two groups of armaments along the anterior margin. Anterior margins of the merus and carpus without long setae; setae as long as or slightly longer than the accompanied spines. Merus has four groups of armamen