Deutella mazatlanensis, Alarcón-Ortega & L.Carballo, 2019

Alarcón-Ortega, Lucy C. & L. Carballo, José, 2019, A new species of Deutella Mayer 1890 (Crustacea: Amphipoda) from the Mexican Pacific coast, Zootaxa 4612 (4), pp. 581-590: 583-585

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Deutella mazatlanensis

n. sp.

Deutella mazatlanensis   n. sp.

( Figs 2–5 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Type material. Holotype male. Islet Hermano Norte (23°11’15.41” N; 106°26’10.30” W), 6 m depth, 11 May 2018, collected from bryozoan Bugula neritina ( Linnaeus, 1758)   , (ICML-EMU-11441). Paratype male (used for drawings of mouthparts) (two vials: one with mouthparts dissected and the other with the rest of the body) (ICML-EMU- 11445); mature female (used for description and drawings of lateral and dorsal view, gnathopod 2 and abdomen) (ICML-EMU-11442); 2 mature females, 3 mature female, 4 juveniles (ICML-EMU-11443); 2 mature males, 2 mature females, 2 juveniles (CNCR-35240), collected together with the holotype. 1 mature male and 1 mature female (ICML-EMU-11444); 1 mature males and 1 mature female (CNCR-35241), Islet Hermano Norte, 4 m depth, 20 August 2018, collected from hydrozoan Macrorhynchia nuttingi ( Hargitt, 1927)   .

Additional material. Islet Hermano Norte, 6 m depth, associated to the bryozoan B. neritina   , 11 May 2018, 10 male, 11 female and 30 juveniles; 4 m depth, associated to the hydrozoan M. nuttingi   , 20 August 2018, 3 mature male, 8 mature female and 10 juveniles. Isla Pájaros (23°14’58.64” N; 106°28’39.89” W), 3 meters depth associated to the sponge Aplysina gerardogreeni Gómez & Bakus, 1992   , 20 August 2018, 1 mature and 1 premature male, 1 female GoogleMaps   .

Type locality. Islet Hermano Norte, Mazatlán, Sinaloa, Mexican Pacific   .

Diagnosis. Head with a dorsal, anteriorly directed projection; Pereonite 2 provided with two dorsal projections, one acute at the middle, and a large rounded one posteriorly and a lateral acute projection anteroventrally projected. Lateral plates of pereonites 3 slightly crenulated; pereonites 5 with posterior sinuous. Antenna 1 and 2 setose. Gnathopod 2 propodus ventrally setose; palm with a proximal rectangular projection provided with a proximal poison tooth and a large distal projection; rectangular projection followed by a concave margin. Dactylus not curved medially. Pereonite 3 and 4 two-articulate.

Etymology. The specific name refers to the Mazatlán Bay, Sinaloa, México the locality where the specimens where collected.

Description. Holotype ICML-EMU-11441 male ( Figs 2–5 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 ) body length 5.38 mm.

Colour of live specimens. Light brown with some small red algae of the family Ceramiaceae Dumortier, 1822   in the dorsal pereonites.

Lateral view ( Fig. 2 View FIGURE 2 ). Head provides with a dorsal acute projection; eyes present; pereonite 1 partially fused with head, suture present. Pereonite 2 with two dorsal projections, one acute at the middle and a large rounded one posteriorly; a lateral acute projection anteroventrally projected. Pereonite 3 with one small anteriorly and posteriorly hump. Pereonites 4–7 dorsally smooth. Lateral plates of pereonites 3 slightly crenulated; pereonites 5 with posterior sinuous.

Gills. Present on pereonites 3–4, elongate, length about 3 times width ( Fig. 2C View FIGURE 2 ).

Mouthparts. Upper lip ( Fig. 3A View FIGURE 3 ) symmetrically bilobed, smooth apically. Mandibles ( Fig. 3F, E View FIGURE 3 ) with 3-articulate palps; second article with one simple setae in the right and left mandible; distal article of palp with 6-ventrodistal setal, the distal one the largest; mandibular molar robust; left mandible ( Fig. 3F View FIGURE 3 ) with incisor and lacinia mobilis 5-toothed, followed by three serrate spines; incisor of right mandible ( Fig. 3E View FIGURE 3 ) 5-toothed, lacinia mobilis with notch, followed by 2 serrate spines. Lower lip ( Fig. 3B View FIGURE 3 ) inner lobes well demarcated; inner and outer lobes without setae. Maxilla 1 ( Fig. 3C View FIGURE 3 ) outer lobe carrying five spine-like setae; distal article of the palp with four distal spines like setae and two setae medially. Maxilla 2 ( Fig. 3D View FIGURE 3 ) inner lobe small and shorter than the outer lobe, with 4 and 6 distally setae respectively. Maxilliped ( Fig. 3G View FIGURE 3 ) inner plate small and elongate with two single seta and 1 tooth at the middle of the distal margin; outer plate about 2.5 times as long as inner plate, with seven setae; palp 4-articulate, scarcely setose; penultimate article of the palp with a distal projection; dactylus without rows of setulae, two setulae distally with a fine seta subdistally.

Antennae. Antenna 1 ( Fig. 4A View FIGURE 4 ) about half of body length; peduncle setose; article 1 robust, second article longest; third article the shortest; flagellum with 10-articulate. Antenna 2 ( Fig. 4B View FIGURE 4 ) almost equal as the first two pe- duncle of antenna 1; basal article of the peduncle provided with a distal acute projection; the rest articles of peduncle abundantly setose flagellum two-articulate.

Gnathopods. Gnathopod 1 ( Fig. 4C View FIGURE 4 ) basis of the same length as the combination of ischium to carpus; propodus triangular, with a proximal grasping spine; grasping margin of propodus palm and dactylus minutely serrate; dactylus bifid distally. Gnathopod 2 ( Fig. 4D View FIGURE 4 ) inserted near distal end of pereonite 2; basis shorter than pereonite 1, small median projection on anterolateral margin; ischium subquadrate; merus trapezoidal wider distally with small anteroventral projection; carpus short; propodus about 1.5 long as basis, ventrally setose; palm with a proximal rectangular projection provided with a proximal small poison tooth and a large distal projection; rectangular projection followed by a concave margin, continued for a distally crenulated margin. Dactylus long, with short setae ventrally on the margin of the distal half.

Pereopods. Pereopods 3 ( Fig. 5A View FIGURE 5 ) and 4 ( Fig. 5B View FIGURE 5 ) two-articulate, both with two setae apically and one plumose seta on distal article and two setae subdistally on basal article; Pereopods 5–7 ( Fig. 5 C, D View FIGURE 5 ) increasing in length respectively; 6-articulate; palm of propodus with a proximal row of three, seven and eight short spines on pereopods 5, 6 and 7 respectively. Dactylus almost as long as the propodus.

Penes. ( Fig. 3F View FIGURE 3 ) rounded, almost as long as wide.

Abdomen. ( Fig. 3F View FIGURE 3 ) with a pair of appendages, serrate distally; a pair of lateral lobes setose and a single dorsal lobe with a pair of short plumose setae distally. Paratype female ICML-EMU-11442 ( Fig. 2 A, B View FIGURE 2 ). Body length 4.65 mm. Antenna 1 less setose; flagellum of antenna 1 with 10 articles. Head with a dorsal acute projection. Pereonite 1 smooth; pereonite 2 with one small dorsal projection at middle. The anterolateral projection on pereonite 2, present in male are absent in female. Gnathopod 2 inserted on the anterior half of pereonite 2; propodus smaller than in male, less setose; and lacking the rectangular projection present in males; proximal grasping spine present ( Fig. 4E View FIGURE 4 ). Oostegites on pereonite 3 and 4 first pair setose, second one scarcely setose. Abdomen without appendages; a pair of lateral lobes and dorsal lobe provided with a pair of single setae ( Fig. 5F View FIGURE 5 ).

Habitat. Specimens of Deutella mazatlanensis   n. sp., were collected from the hydroid Macrorhynchia nuttingi   , the bryozoan Bugula neritina   and the horny sponge Aplysina gerardogreeni   , in shallow waters between 3 to 6 meters depth. In the samples of the hydroid M. nuttingi   , the caprellid D. mazatlanensis   , shared the habitat with other caprellid species such as Caprella mendax Mayer 1903   , with densities of 37 ind/100 ml of substratum and 275 ind/100 ml of substratum, respectively. Meanwhile, D. mazatlanensis   associated with B. neritina   had densities of 111 ind/100 ml of substratum, sharing habitats with other amphipods (44 ind/100 ml of substratum) and pycnogonids (5 ind/100 ml of substratm). Associated with the sponge A. gerardogreeni   , in addition to D. mazatlanensis   , other caprellids live on these substrates such as Aciconula acanthosoma Chess, 1989   , Liropus isabelensis   Sánchez- Moyano, García-Asencio & Guerra-García, 2014 (8 ind/100 ml of substratum), and Paracaprella   sp., the densities of D. mazatlanensis   was relatively low compared with the other substrates (bryozoan and hydroids) reaching solely 1 ind/100 ml of substratum. In the present study, other substrates as sandy bottoms and gorgonians were collected, however, we did not find D. mazatlanensis   in these. According to Guerra-García & Tierno de Figueroa (2009), individuals of Deutella   genus, are mainly detritivores, moreover some species are predators feeding on copepods.

Remarks. The morphological characters of all individual mature males and females of D. mazatlanensis   n. sp., were constant. The size of mature males was 3.47–6.38 mm and for females 3.00– 5.14 mm. Dorsal pattern of projections and humps was similar in males and females, moreover in some adult individuals, they were smaller or barely evident. The number of articles of antenna 1 flagellum varies in males between to 7 to 10; meanwhile in females between to 7 to 9. Pereonite 1 in both male and female without dorsal projection. Pereopods 3 and 4 in the individuals examinated were always 2-articulate.The structure and number of setae on the maxilliped and the maxillae are very constant in all specimens examined. Comparing Deutella mazatlanensis   , with the other Deutella   species, it is close to D. aspiducha Gable & Lazo-Wasem, 1987   and D. venenosa Mayer 1890   , for the presence of the dorsal projections on head and pereonite 2. However, they can be distinguished easily, in the case of D. venenosa   , there is a one projection medially on pereonite 1 and three dorsal projections on pereonite 2 and in D. aspiducha   projection on pereonite 1 is absent and pereonite 2 just with one dorsal projection, meanwhile in D. mazatlanensis   projection in pereonite 1 is absent and pereonite 2 just present two dorsal projections. Pereopod 5 on male in D. aspiducha   dactylus is extremely reduced, in D. venenosa   is well development, about half as long as propodus, meanwhile in D. mazatlanensis   almost as long as the propodus. The present record of the Deutella   genera, constitutes the fourth for the Pacific Ocean and the first record for the tropical Eastern Pacific.