Latin American Journal of Aquatic Research, 47(2):Arms 356-360 regeneration, 2019 in Lolliguncula panamensis 1 DOI: 10.3856/vol47-issue2-fulltext-16 Short Communication Arms regeneration in the squid Lolliguncula panamensis (Mollusca: Cephalopoda) Sairi Saraí León Guzmán1 & María del Carmen Alejo-Plata2 1Posgrado en Ecología Marina, Universidad del Mar Campus Puerto Ángel, Oaxaca, México 2Instituto de Recursos, Universidad del Mar Campus Puerto Ángel, Oaxaca, México Corresponding author: María del Carmen Alejo-Plata ([email protected]) ABSTRACT. During two sampling trips carried out over the continental platform of Gulf of Tehuantepec, a total of 101 Lolliguncula panamensis Berry, 1911 were caught. Thirty mature specimens (19 females and 11 males) were found to have unusually short arms. Dorsal mantle length, arm's length, and body weight were measured from the fresh specimens. Evidence of regeneration was observed at different points along arms; these may have been the result of partial autonomies. In the injured arms, the surface of the arm's tip was wholly covered with skin. Fracture planes were found in our histological sections; the autotomized arms exhibited constricted muscle fibers in the longitudinal sections indicative of wound closing. The arms of the specimens observed were very similar to the regenerating arms of other squids. This study represents the first to report arms regeneration and hectocotylus in this squid wild-caught. These results suggest that Lolliguncula panamensis exhibit partial autotomy, and the ability to regenerate the arms. Additionally, each of the eight arms can do so, presumably during defensive interaction or mating. Keywords: Lolliguncula panamensis; Loliginidae; arm regeneration; autotomy; Gulf of Tehuantepec Lolliguncula panamensis Berry, 2011 is distributed in ned according to the criteria of Tressler et al. (2014): the Eastern Pacific from the Gulf of California, Mexico frayed edge (I), smooth edge (II), growth bud to Peru (Roper et al., 1995), and principally inhabits appearance (III), tip emergence (IV), and tip elongation depths of less than 45 m (Sánchez, 2003). This species (V). Whole individuals were frozen and later fixed in is a highly opportunistic predator foraging primarily in 10% neutral buffered formalin in seawater tallowed by coastal and epipelagic waters (Arizmendi-Rodríguez et preservation in 70% ethanol. Ten arms were dehydrated al., 2011). In Mexico, this species is recurrent in the in a graded alcohol series, cleared with citrosol and bycatch of the shrimp trawl fishery (Alejo-Plata et al., embedded in paraplast. Longitudinal sections of six 2001); however biological information for this species micros thick were made a Leica rotating microtome and is scarce. stained with hematoxylin-eosin and with Massons Two sampling trips were carried out during trichrome (Bancroft et al., 1990). November-December 2017 and May 2018 to the Gulf The proportion of regeneration was of 19% females of Tehuantepec between Salina Cruz (16º08’29”N, and 10% males. Nineteen females had a total of 50 arms 95º10’50”W) and Barra de Suchiate (16º13’00”N, in regeneration (33%) and 11 males with 48 arms in 92º14’30”W) (Fig. 1). A total of 55 bottom trawls were regeneration (60%) (Table 1). Arm regeneration in ale carried out at a depth of 14.7 to 42.8 m using trawl nets may be important because the arms play an important with a 52.5 mm mesh size. A total of 101 L. panamensis role in grasping the female during mating in this were caught. species. Thirty mature specimens (19 females and 11 males) In females, L4 (left arm 4 length) and R4 (right arm were found to have unusually short arms. Dorsal mantle 4 length) were most frequently lost; in males, L2 and length (ML), arm's length (AL), and body weight (BW) R3 were most frequently lost while L4 (hectocotylus) were measured from the fresh specimens (Roper & and R4 were least frequently missing (Fig. 2). An Voss, 1983). Stages of arm regeneration were determi- accident likely relates the unusual shortness of the arms __________________ Corresponding editor: Eduardo Ríos 3572 Latin American Journal of Aquatic Research Figure 1. Study area with locations of 58 bottoms trawls (black dots). White dots indicate records of Lolliguncula panamensis. Figure 2. Lolliguncula panamensis. Arm positions (L1-L4, R1-R4) that are most often autotomized (regeneration arm stub) in the Gulf of Tehuantepec. L: left; R: right. (e.g., feeding, fighting, jigging) (Ikeda et al., 2004) or arms, the surface of the arm's tip was completely with predator avoidance (Bush, 2012). The hecto- covered with skin (Fig. 3). Fracture planes were cotylized arm was less susceptible to injury in com- observed; the autotomized arms exhibited constricted parison to other arms (Fig. 2) as was observed by Bello muscle fibers in the longitudinal sections, indicative of (1995) for bobtail squids; apparently, only the tip of the wound closing, and cells with dark pink nuclei hectocotylus was involved in the traumatic loss and concentrated at the edges of both ends of arm tissue subsequent regeneration process. Besides, protection were observed (Fig. 4). This study represents the first and more rapid regeneration of this specialized arm to to report for arms regeneration and hectocotylus in L. be due to its importance in mating (Wada, 2017). panamensis wild-caught. The arms of the specimens Evidence of regeneration was observed at different observed were very similar to the regenerating arms of points along arms from L. panamensis; these may have other squids (Bello, 1995; Bush, 2012). been the result of partial autotomies. In the injured (II) (II) (II) (II) (II) (II) RAL 6 (III) 2 (IV) 1.5 (III) 1.3 (III) 1.8 (IV) 34 52 54 12 32 37 28 52 28 39 7.8 7.5 28.3 34.9 33.2 51.3 26.9 22.8 16.5 23.6 47.3 54.9 21.5 29.3 21.9 28.3 32.6 34.1 A4 R 10.05 11.83 V) (II) (II) (II) (II) (II) (II) (II) (II) (II) RAL 1.9 ( 2.7 (III) 2.2 (III) 6.7 (III) 29 33 35 33 36 52 16 47 55 29 14 28 40 4.6 13.4 53.4 35.5 10.8 31.5 21.2 27.5 38.2 16.4 16.2 28.2 34.6 56.3 27.2 26.7 37.8 A4 L II (II) (II) (II) (II) (II) (II) (II) (III) RAL 4 (III) 3 (IV) 9.7 (III) 3.8 (IV) 2.2 (IV) 32 31 35 20 43 35 27 40 7.1 32.9 39.4 14.2 32.5 22.8 23.2 24.9 22.8 23.4 37.9 20.8 17.9 35.9 44.7 38.9 30.2 30.7 33.7 30.1 30.6 A3 R 15.45 ) (II (II) (II) (II) RAL 2 (III) 1.5 (III) 1.9 (III) 4.4 (IV) Table 1. Measurements of arms Lolliguncula Panamensis caught at the Gulf of Tehuantepec on November-December 2017 and May 2018. Dorsal mantle length 43 42 35 34 33 32 32 32 25 15 42 23 37 36 45 39 34 26 7.6 15.9 19.9 21.5 17.8 13.2 39.6 15.5 44.8 17.3 27.5 39.1 (DML), total weight (W, g), armA3 L 1 length (A1), arm 2 length (A2), arm 3 length (A3), arm 4 length (A4), left (L), right (R), regenerating arm length (RAL), stage, and length (mm). V) I (II) (II) (II) (II) (II) (II) (II) (II) RAL 2 ( 1.8 (IV) 36 22 19 21 19 22 18 33 5.0 42.8 35.4 22.8 40.6 55.2 20.1 14.8 24.1 13.9 22.3 20.8 47.3 22.1 33.3 20.2 36.7 18.8 25.5 25.7 A2 R 11.23 26.21 Arms regeneration in in regeneration Arms V) ( (II) (II) (II) (II) (II) (II) (II) (II) (II) 9 RAL 2 (IV) 2. 1.2 (IV) 13 40 35 16 15 11 18 22 22 20 18 22 20 32 6.3 36.7 44.3 41.5 16.8 19.3 19.3 20.1 46.1 47.4 19.4 32.3 25.8 31.4 A2 L 11.25 11.22 Lolliguncula panamensis Lolliguncula (II) (II) (II) (II) (II) (II) (II) (II) (II) RAL 8.5 (V) 0.9 (III) 2.5 (III) 1.6 (IV) R 27 30 19 17 21 19 30 12 31 6.8 5.7 13.6 16.9 15.3 15.7 27.5 15.7 13.4 17.7 32.9 20.9 21.3 18.8 10.3 11.7 17.5 21.6 18.1 21.5 A1 10.24 ) (V) I (II) (II) (II) (II) (II) (II) (II) (I (II) (II) RAL 2.7 26 19 17 20 13 18 17 33 30 30 19 12 17 3.9 20.8 15.4 15.7 14.2 19.4 13.5 16.9 18.8 22.1 12.4 27.7 11.3 12.1 18.2 19.3 28.1 A1 L W 33.3 66.7 51.9 36.5 66.3 75 17.8 41 22.8 4.7 1.6 38.6 55 47 66 40.1 54.8 48.4 52.4 46.8 72.5 85.6 52 75.2 14.2 46 81.3 50 20 20 DML 82.4 99.7 99.3 87.3 104 107 65.1 115 73.6 41.1 28.9 84.9 92.3 100 103 91 104 92.9 98.6 104 110 97.5 96.9 109 62 90 105 98 67.1 62.9 7 /18 /17 Date May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 Dec/1 Dec/17 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May/18 May Nov/17 Nov/17 Nov Sex 358 11 M 10 M 9 M 8 M 7 M 6 M 5 M 4 M 3 M 2 M 1 M 19 F 18 F 17 F 16 F 15 F 14 F 13 F 12 F 11 F 10 F 9 F 8 F 7 F 6 F 5 F 4 F 3 F 2 F 1 F 3 3594 Latin American Journal of Aquatic Research Figure 3.